Summary of this article
19p13 duplication syndrome is a rare condition caused by a duplication of a region on the short arm of chromosome 19 (band 19p13) that includes the NFIX gene. When the same NFIX region is instead deleted, the result is Malan syndrome (formerly called Sotos syndrome 2), which is marked by overgrowth. Duplication produces essentially the opposite pattern — growth delay, microcephaly, and intellectual disability — so it is sometimes described as the “mirror image” of Malan syndrome. This article explains the cause, symptoms, inheritance pattern, and diagnostic approach based on published academic reports from Japan and overseas, and also clarifies how the condition relates to NIPT during pregnancy.
What this article covers
- Exactly why “19p13 duplication syndrome” and “Malan syndrome” are so often discussed together
- The growth and developmental features that duplication causes (actual reported data on short stature, microcephaly, and intellectual disability)
- The inheritance pattern, and why a child can be affected even when neither parent tests positive (germline mosaicism)
- What NIPT during pregnancy can and cannot tell you about this condition, and how it relates to a definitive diagnosis
Introduction: Why “Duplication” and “Deletion” Are Discussed Together
You may have come across the term “19p13 duplication” in an explanation of test results. Searching further, you may also have run into other names — “Malan syndrome” or “Sotos syndrome type 2” — and felt confused about how they relate. In fact, these are two distinct conditions that involve the same gene but change in opposite directions.
Band 19p13 on the short arm of chromosome 19 contains a gene called NFIX, which plays a role in nervous system and skeletal development. When this region is duplicated (an extra copy is present), the result is 19p13 duplication syndrome, the topic of this article. When the region is instead deleted (a copy is missing), the result is Malan syndrome (Japanese). For background on the same chromosomal region, see our related article discussing the published report on 19p13.13 microdeletion/microduplication syndrome.
1. Cause — Duplication of the 19p13 Region Involving the NFIX Gene
Let’s start at the genetic level to see how this condition arises.
The 19p13.13 Region and the NFIX Gene
In 2010, a research group led by Dolan first reported a link between copy-number changes in the 19p13.13 region and a distinctive pattern of symptoms. That report compared four patients with a deletion to one patient with a duplication, and identified three candidate genes — MAST1, NFIX, and CALR.
A subsequent, more detailed follow-up study of duplication cases was published in 2017 by a group led by Bonnet. It analyzed a total of ten patients, including the one duplication case from the earlier Dolan report. The duplicated segments ranged in size from 479 kb to 3.1 Mb, and the smallest region of overlap shared by all patients was identified as approximately 422 kb, containing 16 genes.
Why the Duplication Occurs
In the Bonnet report, the duplication was a new (de novo) change — not found in either parent — in six of nine tested cases. It arises by chance during chromosome replication and segregation, and it is not caused by anything the mother did or didn’t do during pregnancy. That is worth saying plainly: there is nothing to blame yourself for.
2. How 19p13 Duplication Syndrome Differs from Malan Syndrome
Even though the same NFIX gene and the same 19p13 region are involved, duplication and deletion produce opposite growth patterns. The table below lays out the differences.
| Comparison | 19p13 Duplication Syndrome | Malan Syndrome (19p13 deletion, NFIX-related) |
|---|---|---|
| Genetic change | Extra copy of a region (16 genes) that includes NFIX | Deletion or loss of function of the NFIX gene or region |
| Height pattern | Growth delay / short stature (7 of 10 reported cases at or below -2SD) | Postnatal overgrowth (about half of reported cases at or above +2SD) |
| Head circumference pattern | Microcephaly (7 of 10 reported cases at or below -2SD) | Macrocephaly (77% of adult cases at or above +2SD) |
| Bone age | Tends to be delayed (5 of 6 tested cases) | Not documented (overgrowth type shows the opposite tendency) |
| Intellectual disability | Ranges from severe to mild; special-needs education was required in all reported cases | Present in nearly all reported cases |
Put simply, 19p13 duplication syndrome is a condition of “slower growth,” while Malan syndrome is one of “faster growth.” Some researchers describe the duplication phenotype as “the mirror image of Malan syndrome.” Always check whether a test result describes a “duplication” or a “deletion” — the distinction matters.
3. Symptoms — Growth Delay, Microcephaly, and a Range of Intellectual Disability
Based on the 2017 Bonnet report of ten patients, let’s look at how often specific symptoms occurred.
Growth and Head Circumference
Of the ten patients reported, eight showed growth delay, and seven had short stature at or below -2SD. Seven also had microcephaly at or below -2SD, and among the six whose bone age was assessed, five showed delayed bone age.
Intellectual Development and Facial Features
The degree of intellectual disability ranges widely, from cases with almost no expressive language to milder cases. Regardless of severity, however, special-needs education was required in every reported case. Regarding facial features, relatively common findings included full/chubby cheeks (6 of 10), short fingers (brachydactyly, 5 of 10), arched eyebrows (4 of 10), and a full, everted lower lip (4 of 10).
In our own NIPT consultations, we often hear that an unfamiliar diagnosis name on a test report brings anxiety before anything else. That said, how symptoms present varies a great deal from person to person, and this list will not necessarily apply exactly to your own child. The actual outlook is something a clinical geneticist can assess only after an in-person evaluation.
4. Inheritance Pattern — What It Means for a Future Child
19p13 duplication syndrome follows an autosomal dominant pattern. If one parent carries the duplication, each child — regardless of sex — has roughly a 50% chance of inheriting it.
That said, the Bonnet report found the duplication to be a new, non-inherited change in six of nine tested cases. One striking finding: in a pair of siblings, both carried the identical duplication even though blood testing found no trace of it in either parent. This is a phenomenon known as germline mosaicism, in which the change is present only in some of a parent’s sperm or egg cells and therefore goes undetected on a standard blood test.
In other words, a normal parental test result cannot completely rule out the possibility of a similar change in a future child. For an individual assessment of the risk to a future pregnancy, please consult a certified genetic counselor or a board-certified clinical geneticist.
5. Diagnosis
19p13 duplication syndrome is most often identified through chromosomal-level testing prompted by developmental delay or distinctive facial features.
Chromosomal Microarray Analysis (CMA)
In the Bonnet report, duplications were detected using array CGH or SNP array testing at a resolution of 44k to 180k. Because a change this small cannot be found with conventional microscope-based karyotyping (G-banding), a high-resolution test such as chromosomal microarray analysis (CMA) is required.
Confirmation with FISH or Quantitative PCR
Once a microarray test finds a duplication, FISH (fluorescence in situ hybridization) or quantitative PCR is often used to check whether either parent carries the same change. That result becomes the basis for determining the inheritance pattern and assessing the risk to a future child.
6. Treatment and Day-to-Day Support
There is currently no treatment that reverses the underlying duplication. Care instead centers on developmental therapies and ongoing monitoring of growth.
Developmental Support and Special-Needs Education
Physical, occupational, and speech therapy are combined to support motor and language development. Because every reported case required special-needs education, it helps to talk with the school early, well before enrollment, so a learning environment suited to your child can be arranged.
Monitoring Growth and Bone Age
- Have a pediatrician or pediatric endocrinologist regularly track short stature and microcephaly.
- If bone age is delayed, X-rays are used to track the pace of growth over time.
- If behavioral traits are a concern, a psychologist’s evaluation can help clarify the picture.
7. Prognosis — The Long-Term Outlook
19p13 duplication syndrome is not a progressive disease. With ongoing developmental therapy and educational support matched to the degree of intellectual disability, most patients go on to live stable daily lives.
At the same time, the number of reported cases remains small, so how the condition typically unfolds in adulthood is still an open question that will depend on further follow-up research. Regular medical visits, with support adjusted to the person’s changing needs, remain the most important part of ongoing care.
8. How This Relates to NIPT During Pregnancy
Basic NIPT, which screens for trisomy 21, 18, and 13, does not cover small chromosomal duplications or deletions such as 19p13. Some testing plans offer an optional expanded panel that includes microdeletions and microduplications, but exactly which conditions are covered varies by testing facility and plan.
Whether the plan you are considering covers the 19p13 region is something you should confirm directly with the facility performing the test. You may also find it useful to read our articles on how NIPT detects microdeletion syndromes (Japanese) and our overview of microdeletion and microduplication conditions (Japanese).
One more important point: NIPT is only a non-diagnostic screening test. If it returns a positive finding, a definitive diagnosis requires a follow-up procedure such as amniocentesis. The sample obtained is then analyzed with chromosomal microarray analysis (CMA) to check the copy number of the region that includes the NFIX gene. It’s also worth knowing that conventional microscope-based karyotyping alone cannot detect a change this small.
While preparing this article, we searched for first-hand accounts related to this condition posted on X (formerly Twitter) in Japan, but found no recent posts. That is not unusual for a rare disease with a very small patient population. In their place, this article draws on the peer-reviewed reports by Dolan et al. (2010) and Bonnet et al. (2017), along with public information on NFIX-related conditions from Japan and overseas.
If you’re not sure which testing plan fits your situation, try our Plan Finder tool.
9. A Message to Families
The word “duplication” alone can leave you with a vague sense of dread. But 19p13 duplication syndrome follows a different course than overgrowth conditions like Malan syndrome — it’s a condition you manage over time mainly through developmental therapy and educational support.
Ongoing developmental therapy and regular medical visits can place a real burden on a family over the long term. Working alongside your medical team and support organizations, and pacing yourselves, makes that burden easier to carry.
In genetic counseling, one of the most common questions we hear is, “If both of us tested normal, could our child still be affected?” As germline mosaicism shows, there are situations a blood test simply cannot rule out. Please don’t carry that uncertainty alone — bring it to a specialist.
We also welcome phone inquiries (Japanese-language line): 0120-169-629.
Frequently Asked Questions
Are 19p13 duplication syndrome and Malan syndrome the same condition?
No. They involve the same NFIX gene and the same 19p13 region, but they are distinct conditions. A duplication of the region causes 19p13 duplication syndrome, the topic of this article, while a deletion causes Malan syndrome (formerly Sotos syndrome type 2) — and the two show opposite growth patterns.
What symptoms does 19p13 duplication syndrome cause?
Growth delay, short stature, and microcephaly are the most commonly reported features. Intellectual disability ranges from severe to mild, but special-needs education was required in every reported case regardless of severity.
Can it be passed on to a future child?
Because it is autosomal dominant, a parent who carries the duplication has roughly a 50% chance, regardless of sex, of passing it to each child. That said, most reported cases were new (de novo) changes not found in either parent, and in rare cases a child can be affected even when both parents’ blood tests are normal, due to germline mosaicism. For specifics about your situation, please consult a genetic counselor.
Can NIPT during pregnancy detect this condition?
It is not covered by basic NIPT, which screens for trisomy 21, 18, and 13. Some plans offer an optional panel that includes microdeletions and microduplications, but coverage varies by facility, so confirm directly with the facility you’re considering. If a positive finding does occur, a definitive diagnosis requires a follow-up test such as amniocentesis.
What test confirms the diagnosis?
Chromosomal microarray analysis (CMA), using array CGH or SNP array technology, detects the duplication. Once found, FISH or quantitative PCR is used to check the parents and help determine the inheritance pattern.
Is Malan syndrome a designated intractable disease in Japan?
As of 2026, Malan syndrome and other NFIX-related conditions are not included on Japan’s list of designated intractable diseases. For questions about medical-expense assistance or developmental-support programs, please check with your physician or your local municipal office.
Medical supervision: Dr. Hiroshi Oka — 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 the few physicians in Japan to hold laboratory director credentials, and is the author of a Japanese-language book for expectant parents on what to read first after learning of a pregnancy. This article was prepared in line with Japan’s medical advertising guidelines, drawing on peer-reviewed academic reports and information from public and academic institutions. Reported figures come from a limited number of published cases and may be revised as further research accumulates; please consult your physician for decisions about diagnosis and treatment.
References: Dolan et al. (2010), report on 19p13.13 microdeletion/microduplication syndrome | PubMed (U.S. National Library of Medicine) / Bonnet et al. (2017), clinical characterization of 19p13 duplications involving NFIX | PMC (U.S. National Library of Medicine) / NFIX-Related Malan Syndrome | GeneReviews (NCBI Bookshelf) / Malan Syndrome (NFIX-related disorder) | GENIE Rare and Undiagnosed Disease Support System (Tokyo Metropolitan Children’s Medical Center) / Certification (Clinical Genetics Specialist / Certified Genetic Counselor) | Japan Society of Human Genetics
日本皮膚科学会 皮膚科専門医／日本医師会 産業医／東京衛生検査所 指導監督医
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