{"id":84355,"date":"2024-11-15T15:40:28","date_gmt":"2024-11-15T06:40:28","guid":{"rendered":"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/"},"modified":"2026-07-12T21:19:21","modified_gmt":"2026-07-12T12:19:21","slug":"15q13-3-deletion-syndrome-bp4-to-bp5-gain","status":"publish","type":"post","link":"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en","title":{"rendered":"15q13.3 Deletion Syndrome (BP4 to BP5)"},"content":{"rendered":"\n<div style=\"border:solid #ffe6e6 0.8rem;background-color: #fff9f9;padding:3% 5%;margin:1rem 0 3rem;\"><div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">\u76ee\u6b21<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Summary\" >Summary<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#What_Is_15q133_Deletion_Syndrome\" >What Is 15q13.3 Deletion Syndrome?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#How_Rare_Is_This_Condition\" >How Rare Is This Condition?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Deletion_Loss_vs_Duplication_Gain_%E2%80%94_Dont_Confuse_the_Two\" >Deletion (Loss) vs. Duplication (Gain) \u2014 Don&#8217;t Confuse the Two<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Main_Symptoms_%E2%80%94_Epilepsy_Intellectual_Disability_and_Autism_Spectrum_Disorder\" >Main Symptoms \u2014 Epilepsy, Intellectual Disability, and Autism Spectrum Disorder<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Epilepsy_and_Its_Link_to_Idiopathic_Generalized_Epilepsy\" >Epilepsy (and Its Link to Idiopathic Generalized Epilepsy)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Intellectual_Disability_Developmental_Delay_and_Autism_Spectrum_Disorder\" >Intellectual Disability, Developmental Delay, and Autism Spectrum Disorder<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Psychiatric_Risk_and_Why_Some_People_Have_No_Symptoms\" >Psychiatric Risk, and Why Some People Have No Symptoms<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Cause_%E2%80%94_the_CHRNA7_Gene_and_Incomplete_Penetrance\" >Cause \u2014 the CHRNA7 Gene and Incomplete Penetrance<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Diagnosis_%E2%80%94_Confirmed_by_Chromosomal_Microarray_Testing\" >Diagnosis \u2014 Confirmed by Chromosomal Microarray Testing<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Where_This_Fits_Among_Prenatal_Tests_Its_Relationship_to_NIPT\" >Where This Fits Among Prenatal Tests (Its Relationship to NIPT)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#A_Definitive_Diagnosis_Requires_Amniocentesis_or_Chorionic_Villus_Sampling\" >A Definitive Diagnosis Requires Amniocentesis or Chorionic Villus Sampling<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Approaching_the_Decision_About_Prenatal_Testing\" >Approaching the Decision About Prenatal Testing<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Managing_Epilepsy_and_Developmental_Medical_Support\" >Managing Epilepsy and Developmental \/ Medical Support<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Support_for_Families_and_Where_to_Turn_for_Help\" >Support for Families and Where to Turn for Help<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Frequently_Asked_Questions\" >Frequently Asked Questions<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Q_Can_NIPT_detect_15q133_deletion_syndrome\" >Q. Can NIPT detect 15q13.3 deletion syndrome?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Q_Whats_the_difference_between_deletion_syndrome_and_duplication_syndrome\" >Q. What&#8217;s the difference between deletion syndrome and duplication syndrome?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Q_How_is_a_definitive_diagnosis_reached\" >Q. How is a definitive diagnosis reached?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Q_Is_this_caused_by_anything_the_parents_did_%E2%80%94_their_parenting_or_how_the_pregnancy_was_managed\" >Q. Is this caused by anything the parents did \u2014 their parenting or how the pregnancy was managed?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Q_How_severe_are_the_symptoms_likely_to_be\" >Q. How severe are the symptoms likely to be?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-deletion-syndrome-bp4-to-bp5-gain\/?lang=en\/#Q_Im_not_sure_whether_to_have_prenatal_testing_What_should_I_do\" >Q. I&#8217;m not sure whether to have prenatal testing. What should I do?<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2 style=\"margin-top:1rem;\"><span class=\"ez-toc-section\" id=\"Summary\"><\/span>Summary<span class=\"ez-toc-section-end\"><\/span><\/h2><p><strong>15q13.3 deletion syndrome is a very rare chromosomal condition caused by the loss of genetic material in the region from BP4 to BP5 within band q13.3 on the long arm of chromosome 15.<\/strong> CHRNA7 is thought to be the key gene involved, and the condition can involve epilepsy, intellectual disability, autism spectrum disorder, and an increased risk of psychiatric illness \u2014 but how these show up varies enormously from person to person. One hallmark of this syndrome is &#8220;incomplete penetrance&#8221;: some people who carry the exact same deletion have little or no noticeable symptoms at all. A definitive diagnosis requires chromosomal microarray testing, and this condition is not part of standard <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a> (non-invasive prenatal testing). Confirming it prenatally requires amniocentesis or chorionic villus sampling. There is also a separate, distinct condition in which the same region is duplicated rather than deleted \u2014 a &#8220;duplication syndrome.&#8221; This article is careful to distinguish deletion (loss) from duplication (gain), since the two are different conditions.<\/p><\/div>\n\n\n\n<div style=\"border:1px solid #e8608a;border-radius:8px;background:#fff5f8;padding:4% 5%;margin:1rem 0 2.5rem;\">\n<p style=\"font-weight:bold;font-size:1.05em;margin-top:0;\">What you&#8217;ll learn in this article<\/p>\n<ul style=\"margin-bottom:0;\">\n<li>What 15q13.3 deletion syndrome is, and how it relates to the CHRNA7 gene<\/li>\n<li>The overall picture of the main symptoms \u2014 epilepsy, intellectual disability, autism spectrum disorder \u2014 and why they vary so much between individuals<\/li>\n<li>The difference between deletion (loss) and duplication (gain), and how to avoid confusing the two<\/li>\n<li>How this condition relates to <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a>, and the path to a definitive diagnosis through chromosomal microarray testing<\/li>\n<li>Managing epilepsy, developmental support options, and support resources families can turn to<\/li>\n<\/ul>\n<\/div>\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_15q133_Deletion_Syndrome\"><\/span>What Is 15q13.3 Deletion Syndrome?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>15q13.3 deletion syndrome is a very rare congenital condition caused by the loss of part of the genetic material in the region from BP4 to BP5, within band q13.3 on the long arm of chromosome 15.<\/strong> This region contains six genes \u2014 MTMR15, TRPM1, MTMR10, KLF13, OTUD7A, and CHRNA7 \u2014 and the activity of CHRNA7 in particular is thought to be strongly linked to the symptoms. Let&#8217;s start with the overall picture of the condition.<\/p>\n\n\n\n<p>A &#8220;microdeletion&#8221; refers to the loss of a very small segment of a chromosome. These are often too small to detect with conventional microscope-based chromosome analysis, and are frequently only identified through more detailed testing. &#8220;BP4&#8221; and &#8220;BP5&#8221; are simply labels for the breakpoints marking the edges of this region. Even among people with a deletion in the same BP4\u2013BP5 range, the exact size of what is missing can differ from person to person.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Rare_Is_This_Condition\"><\/span><strong>How Rare Is This Condition?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>15q13.3 deletion syndrome is extremely rare in the general population, and a precise prevalence figure has not yet been firmly established. However, studies of people with idiopathic generalized epilepsy, a specific epilepsy subtype, have reported this deletion at a clearly higher rate than in healthy control groups. Japanese proposed diagnostic criteria note that intellectual disability is seen in more than half of reported cases, and seizures in roughly 28%.<\/p>\n\n\n\n<p>Numbers alone can sound alarming, but a defining feature of this condition is that a meaningful number of people have no symptoms at all. It helps to keep in mind that this condition is rare enough that its frequency can&#8217;t be pinned down precisely, and that individual variation is large \u2014 that combination is what makes a calm, grounded understanding possible.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Deletion_Loss_vs_Duplication_Gain_%E2%80%94_Dont_Confuse_the_Two\"><\/span><strong>Deletion (Loss) vs. Duplication (Gain) \u2014 Don&#8217;t Confuse the Two<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Chromosomal changes broadly fall into two categories: deletion and duplication. A deletion (loss) means genetic material is missing; a duplication (gain) means there is extra genetic material. Even within the exact same BP4\u2013BP5 range of 15q13.3, a deletion and a duplication are treated as entirely different conditions.<\/p>\n\n\n\n<p>This article covers 15q13.3 deletion syndrome \u2014 the &#8220;loss&#8221; type. The &#8220;gain&#8221; type, in which genetic material in the same region is duplicated instead, is a separate condition known as 15q13.3 duplication syndrome (covered in a companion Japanese-language article: <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/15q13-3-duplication-syndrome-bp4-to-bp5-gain\/\">15q13.3 duplication syndrome<\/a>). Duplication syndrome tends to show a wider range of symptom presentations than deletion syndrome, and many people with it have no symptoms at all. If you or your child has been tested, check your test report to see whether it specifies a deletion or a duplication.<\/p>\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Main_Symptoms_%E2%80%94_Epilepsy_Intellectual_Disability_and_Autism_Spectrum_Disorder\"><\/span>Main Symptoms \u2014 Epilepsy, Intellectual Disability, and Autism Spectrum Disorder<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>The main features associated with 15q13.3 deletion syndrome are epilepsy, intellectual disability or developmental delay, autism spectrum disorder, and an increased risk of psychiatric conditions such as schizophrenia and bipolar disorder \u2014 and both which symptoms appear and how severe they are vary enormously from person to person.<\/strong> Not everyone shows every feature, and some people have no noticeable symptoms whatsoever. Here is an overview of the most commonly reported features.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Epilepsy_and_Its_Link_to_Idiopathic_Generalized_Epilepsy\"><\/span><strong>Epilepsy (and Its Link to Idiopathic Generalized Epilepsy)<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Epilepsy is one of the best-studied features of this condition. Studies of people with idiopathic generalized epilepsy have found a clearly higher rate of 15q13.3 deletions than in healthy individuals. Seizure type and severity vary widely from person to person.<\/p>\n\n\n\n<p>When epilepsy is identified, treatment moves forward together with a pediatric neurologist or neurologist, using anti-seizure medication matched to the seizure type. Keeping a log of seizures makes it easier to share what&#8217;s happening with the care team at each visit.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Intellectual_Disability_Developmental_Delay_and_Autism_Spectrum_Disorder\"><\/span><strong>Intellectual Disability, Developmental Delay, and Autism Spectrum Disorder<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Intellectual disability is reported in more than half of documented cases. It tends to be mild to moderate, but some people have intellectual development that falls within a broadly typical range. A tendency toward slower language and communication development has also been reported.<\/p>\n\n\n\n<p>Traits related to social communication associated with autism spectrum disorder can also be present. For more on how intellectual development connects with pregnancy-related questions in general, see our related Japanese-language article, <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/intellectual-disability-risk-pregnancy\/\">Intellectual Disability Risk and Pregnancy<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Psychiatric_Risk_and_Why_Some_People_Have_No_Symptoms\"><\/span><strong>Psychiatric Risk, and Why Some People Have No Symptoms<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>From adulthood onward, the risk of psychiatric conditions such as schizophrenia and bipolar disorder is reported to be somewhat elevated. This does not mean these conditions are certain to develop. Ongoing monitoring over time, together with a care setup that allows for early consultation if something feels different, can make a real difference.<\/p>\n\n\n\n<p>This is where the concept of &#8220;incomplete penetrance&#8221; matters. Even among people with the exact same deletion, a meaningful number show no noticeable symptoms at all. That degree of individual variation is part of what makes 15q13.3 deletion syndrome hard to fully pin down \u2014 and, at the same time, it&#8217;s a source of real reassurance.<\/p>\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Cause_%E2%80%94_the_CHRNA7_Gene_and_Incomplete_Penetrance\"><\/span>Cause \u2014 the CHRNA7 Gene and Incomplete Penetrance<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>The symptoms of 15q13.3 deletion syndrome are thought to be largely driven by reduced function of the CHRNA7 gene, which encodes the alpha-7 subunit of a nicotinic acetylcholine receptor in the brain.<\/strong> Several other genes also lie within the deleted region, but a shortage of CHRNA7 gene dosage (haploinsufficiency) is considered the central driver of the symptoms.<\/p>\n\n\n\n<p>The inheritance pattern is autosomal dominant with incomplete penetrance. Reports indicate that roughly 75% of these deletions are inherited from one parent, and that parent frequently has no obvious symptoms, or only very mild ones. The remaining cases arise as new (de novo) changes, for example during the formation of sperm or egg cells.<\/p>\n\n\n\n<p>In genetic counseling, I have repeatedly met parents who blame themselves, feeling that their child&#8217;s serious symptoms must be &#8220;their fault.&#8221; But because penetrance is incomplete, it is entirely possible for a parent with no symptoms to have a child with more pronounced symptoms. That outcome is nobody&#8217;s fault \u2014 it is simply how this form of inheritance works.<\/p>\n\n\n\n<p>If you&#8217;d like a clearer picture for future family planning, chromosomal microarray testing of both parents can determine whether the deletion was inherited or arose as a new mutation. If this concerns you, please speak with a specialist through genetic counseling.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Diagnosis_%E2%80%94_Confirmed_by_Chromosomal_Microarray_Testing\"><\/span>Diagnosis \u2014 Confirmed by Chromosomal Microarray Testing<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>15q13.3 deletion syndrome is confirmed through chromosomal microarray testing, which can detect very small chromosomal deletions or duplications.<\/strong> Subtle changes that are hard to detect with conventional microscope-based chromosome analysis (karyotyping) can be picked up with this test. Here is how prenatal and postnatal testing pathways each work.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Where_This_Fits_Among_Prenatal_Tests_Its_Relationship_to_NIPT\"><\/span><strong>Where This Fits Among Prenatal Tests (Its Relationship to NIPT)<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>There&#8217;s an important point worth knowing upfront. <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a> (non-invasive prenatal testing) is a non-definitive screening test that primarily looks at numerical chromosomal changes such as trisomy 13, 18, and 21. <strong>A microdeletion like 15q13.3 is not part of standard <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a>.<\/strong> Some clinics offer it as an optional expanded-panel item, but the range covered is limited and detection rates vary.<\/p>\n\n\n\n<p>Because of this, even if an optional expanded test reports &#8220;elevated probability,&#8221; that alone does not confirm a diagnosis. This is not a test that can promise unlimited accuracy \u2014 that&#8217;s an important point to keep in mind. For the full picture of what standard <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a> does and does not cover, see our related Japanese-language article, <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/nipt-detectable-conditions\/?lang=en\">Conditions NIPT Can Detect<\/a>. For more on how microdeletion syndromes in general relate to <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a>, see <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/nipt-microdeletion-risks\/?lang=en\">Microdeletion Syndromes and NIPT<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"A_Definitive_Diagnosis_Requires_Amniocentesis_or_Chorionic_Villus_Sampling\"><\/span><strong>A Definitive Diagnosis Requires Amniocentesis or Chorionic Villus Sampling<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>A definitive diagnosis is made by taking cells collected through amniocentesis or chorionic villus sampling and examining them with chromosomal microarray testing. These are definitive, diagnostic tests, but they carry a small risk of miscarriage \u2014 reported at roughly 0.3% for amniocentesis and roughly 1% for chorionic villus sampling.<\/p>\n\n\n\n<p>Whether to proceed is a decision for each family to make, weighing that risk against the value of the information gained. Details on the definitive test itself are covered in our related Japanese-language article, <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/amniotic-fluid-test-about\/?lang=en\">About Amniocentesis<\/a>. After birth, chromosomal microarray testing can be done from a simple blood draw, with no miscarriage risk involved.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Test<\/th><th>Category<\/th><th>Relevance to 15q13.3 Deletion<\/th><th>Physical Burden<\/th><\/tr><\/thead><tbody><tr><td><a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a> (non-invasive prenatal testing)<\/td><td>Non-definitive screening test<\/td><td>Not part of standard <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a>. Offered as an optional expanded item at some clinics; coverage and detection rates vary<\/td><td>Blood draw only<\/td><\/tr><tr><td>Amniocentesis + chromosomal microarray<\/td><td>Definitive diagnostic test<\/td><td>Can confirm the precise extent of the deletion<\/td><td>Miscarriage risk approx. 0.3%<\/td><\/tr><tr><td>Chorionic villus sampling + chromosomal microarray<\/td><td>Definitive diagnostic test<\/td><td>Can confirm the diagnosis earlier in pregnancy<\/td><td>Miscarriage risk approx. 1%<\/td><\/tr><tr><td>Postnatal blood test + chromosomal microarray<\/td><td>Definitive diagnostic test<\/td><td>Can confirm the diagnosis after birth<\/td><td>Blood draw only<\/td><\/tr><\/tbody><\/table><figcaption>Comparison of tests relevant to 15q13.3 deletion syndrome (category and physical burden)<\/figcaption><\/figure>\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Approaching_the_Decision_About_Prenatal_Testing\"><\/span>Approaching the Decision About Prenatal Testing<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>There is no single right answer to whether you should undergo prenatal testing \u2014 choosing to test and choosing not to are both meaningful, valid decisions for a family to make.<\/strong> Feeling torn is completely natural. Here we look at how other people have thought it through, drawing on real voices from those who have faced this decision.<\/p>\n\n\n\n<p>In counseling sessions, I have often heard people say, &#8220;I was sure I&#8217;d have <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a>, but once I actually got pregnant, I hesitated.&#8221; On X, <a href=\"https:\/\/x.com\/sisisi195275806\" target=\"_blank\" rel=\"noopener\">@sisisi195275806<\/a> wrote candidly about having been fully intending to get <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a>, then feeling deeply torn once pregnant \u2014 and being glad, in the end, that she went through with it. The process of wavering and working through the decision is, in itself, a way of engaging with your baby.<\/p>\n\n\n\n<p>Other people, after much thought, decide not to test at all this time. On X, <a href=\"https:\/\/x.com\/mmy338\" target=\"_blank\" rel=\"noopener\">@mmy338<\/a> wrote about wrestling with the decision over prenatal testing and arriving at the conclusion that, this time, she would not pursue it. A decision not to test, reached after real reflection, is just as legitimate a choice \u2014 and it isn&#8217;t for anyone else to rank one decision above the other.<\/p>\n\n\n\n<p>If you&#8217;re torn, please don&#8217;t carry it alone \u2014 genetic counseling gives you a chance to talk it through with a specialist. Together, you can sort out what a test can and can&#8217;t tell you, and what your options are afterward. Our related Japanese-language article on how one family worked through this decision, <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/nipt-202407001\/\">a family&#8217;s testing consultation case study<\/a>, may also be a useful reference.<\/p>\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Managing_Epilepsy_and_Developmental_Medical_Support\"><\/span>Managing Epilepsy and Developmental \/ Medical Support<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>There is no treatment that cures 15q13.3 deletion syndrome itself, but combining epilepsy management with developmental support can meaningfully help a child thrive.<\/strong> Support is typically provided by a team of specialists, matched to each child&#8217;s specific combination of features. Here are the main pillars of support.<\/p>\n\n\n\n<p>When epilepsy is present, care continues in partnership with a pediatric neurologist or neurologist, using anti-seizure medication matched to seizure type. Recording the frequency and pattern of seizures helps with fine-tuning medication. For children whose motor or language development is progressing slowly, physical therapy, occupational therapy, and speech therapy can all be valuable.<\/p>\n\n\n\n<p>When traits associated with autism spectrum disorder are present, behavioral support and coordination with local developmental support services or special-needs education are also options worth considering. From adulthood onward, an ongoing relationship with a primary care physician helps changes in mood or behavior get noticed and addressed early.<\/p>\n\n\n\n<p>If you&#8217;re not sure where to start, your child&#8217;s pediatrician or your local public health center is a good first stop \u2014 from there, you can be connected to the right resources for epilepsy, development, or behavioral support.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Support_for_Families_and_Where_to_Turn_for_Help\"><\/span>Support for Families and Where to Turn for Help<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>Because this is such a rare condition, knowing about public consultation services and diagnostic-criteria resources early on can be a real source of support so families don&#8217;t feel isolated.<\/strong> Long-term medical care and developmental support take time and emotional energy. Here are some resources worth knowing about.<\/p>\n\n\n\n<p>For information on rare and intractable diseases (in Japanese), Japan&#8217;s <a href=\"https:\/\/www.nanbyou.or.jp\/\" target=\"_blank\" rel=\"noopener\">Center for Intractable Disease Information<\/a> is a useful resource. For developmental support, Japan&#8217;s <a href=\"https:\/\/www.rehab.go.jp\/ddis\/\" target=\"_blank\" rel=\"noopener\">National Rehabilitation Center for Persons with Disabilities \u2014 Developmental Disability Information and Support Center<\/a> outlines where to find consultation and support. Japanese specialists&#8217; proposed diagnostic criteria are also summarized in this <a href=\"http:\/\/square.umin.ac.jp\/CMA\/12_diagnosis.pdf\" target=\"_blank\" rel=\"noopener\">academic reference on 15q13.3 microdeletion syndrome<\/a> (Japanese, PDF). For neutral background on prenatal testing itself, Japan&#8217;s <a href=\"https:\/\/jams-prenatal.jp\/\" target=\"_blank\" rel=\"noopener\">Japanese Association of Medical Sciences Committee on Prenatal Testing Certification<\/a> is another helpful resource.<\/p>\n\n\n\n<p>Closer to home, local public health centers, child development support centers, and family support groups made up of people with similar experiences can all make a real difference. Connecting with families walking a similar path makes it easier to share day-to-day strategies and process feelings together. Financial assistance programs for medical care and developmental support may also be available, so it&#8217;s worth checking with your local municipal office.<\/p>\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Frequently_Asked_Questions\"><\/span>Frequently Asked Questions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Q_Can_NIPT_detect_15q133_deletion_syndrome\"><\/span><strong>Q. Can NIPT detect 15q13.3 deletion syndrome?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>This microdeletion is not part of standard <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a> (non-invasive prenatal testing). Some clinics offer it as an optional expanded-panel item, but the range covered is limited and detection rates vary. Because <a href=\"https:\/\/www.hiro-clinic.or.jp\/nipt\/\">NIPT<\/a> is a non-definitive screening test, an elevated probability result alone does not confirm a diagnosis. A definitive diagnosis requires chromosomal microarray testing of cells collected through amniocentesis or chorionic villus sampling.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Q_Whats_the_difference_between_deletion_syndrome_and_duplication_syndrome\"><\/span><strong>Q. What&#8217;s the difference between deletion syndrome and duplication syndrome?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>A deletion (loss) means chromosomal genetic material is missing; a duplication (gain) means there is extra genetic material. Even within the same BP4\u2013BP5 range of 15q13.3, a deletion and a duplication are treated as entirely different conditions. Duplication syndrome tends to show a wider range of symptom presentations than deletion syndrome, and many people with it have no symptoms at all. Check your test report to see whether it specifies &#8220;deletion&#8221; or &#8220;duplication.&#8221;<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Q_How_is_a_definitive_diagnosis_reached\"><\/span><strong>Q. How is a definitive diagnosis reached?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>A definitive diagnosis is reached through chromosomal microarray testing, which can detect small chromosomal deletions or duplications. Prenatally, this is done on cells collected via amniocentesis or chorionic villus sampling. After birth, it can be done from a blood draw with no miscarriage risk involved. Subtle changes that conventional microscope-based chromosome analysis can miss are picked up by this test.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Q_Is_this_caused_by_anything_the_parents_did_%E2%80%94_their_parenting_or_how_the_pregnancy_was_managed\"><\/span><strong>Q. Is this caused by anything the parents did \u2014 their parenting or how the pregnancy was managed?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>No, it is not. Roughly 75% of these deletions are inherited from one parent, and that parent often has no obvious symptoms \u2014 this is a result of incomplete penetrance, a feature of how this condition is inherited. The remaining cases arise as new (de novo) genetic changes. It has nothing to do with parenting style or how the pregnancy was managed; it is a genetic event that can happen to anyone. If this concerns you, genetic counseling is available to talk it through.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Q_How_severe_are_the_symptoms_likely_to_be\"><\/span><strong>Q. How severe are the symptoms likely to be?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>There is enormous individual variation in how symptoms present. Some people have prominent epilepsy or intellectual disability, while others show no noticeable symptoms at all \u2014 a feature known as incomplete penetrance. Rather than assuming an &#8220;average&#8221; case, it helps to look carefully at what&#8217;s actually happening for your own child or yourself, and build support around that.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Q_Im_not_sure_whether_to_have_prenatal_testing_What_should_I_do\"><\/span><strong>Q. I&#8217;m not sure whether to have prenatal testing. What should I do?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Choosing to test and choosing not to are both meaningful, valid decisions for your family. Feeling torn is natural, so please don&#8217;t carry it alone. Genetic counseling lets you talk it through with a specialist, sorting out what a test can and can&#8217;t tell you and what your options are afterward. The process of reaching a decision you feel at peace with is, in itself, a way of engaging with your baby.<\/p>\n\n\n\n<div style=\"border:1px solid #f0d0dc;border-radius:12px;padding:1.2em 1.4em;margin:2.5rem 0 1rem;background:#fffafc;\">\n<p style=\"margin:0 0 0.4em;font-weight:bold;\">Author \/ Medical Supervision<\/p>\n<p style=\"margin:0;\">Dr. Hiroshi Oka \u2014 Director-in-Chief and Lab Director, Hiro Clinic (Fukumikai Medical Corporation). A graduate of Keio University School of Medicine, Dr. Oka holds a Ph.D. in Medicine and has passed the national medical licensing examinations of both Japan and the United States. He is one of only around 20 physicians in Japan to hold laboratory director credentials, and shares evidence-based information on pregnancy and prenatal testing through his YouTube channel, &#8220;Dr. Hiroshi&#8217;s Evidence-Based Pregnancy Channel.&#8221;<\/p>\n<\/div>\n\n\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\"@type\":\"Question\",\"name\":\"Can NIPT detect 15q13.3 deletion syndrome?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"This microdeletion is not part of standard NIPT (non-invasive prenatal testing). Some clinics offer it as an optional expanded-panel item, but the range covered is limited and detection rates vary. 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