DiGeorge syndrome (22q11.2)

Overview

DiGeorge syndrome (DiGeorge syndrome) is a genetic disorder based on a minute deletion in gene 22q11.2. It presents with a variety of symptoms, including immunodeficiency and congenital cardiovascular abnormalities due to hypoplastic or dysplastic thymus and parathyroid glands. It also presents with characteristic facial features such as a hypoplasia of the auricularia and cleft midline lip and palate.

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Epidemiology

It is estimated at 1 in 4,000 to 6,000 people.

Cause

People diagnosed with DiGeorge syndrome have a partial deletion of DNA on chromosome 22. This missing DNA contains several genes that affect body development, but the loss of the gene TBX1 is thought to be the likely cause of many of the characteristic signs of the syndrome (such as heart defects, cleft palate, characteristic facial features, hearing loss and low calcium levels). Some studies suggest that deletion of this gene may also contribute to behavioural problems.

Symptoms

Patients are often born with heart defects, recurrent infections caused by immune system problems and characteristic facial features. Patients have abnormalities in the muscles that form the palate, a condition known as submucosal cleft palate. A submucosal cleft palate causes air to escape through the nose during speech, making normal speech difficult. Patients may also present with breathing problems, kidney abnormalities, hypocalcaemia, thrombocytopenia, significant feeding difficulties, gastrointestinal problems, hearing loss, and may also present with skeletal abnormalities such as mild short stature and, rarely, spinal abnormalities.

Many children with DiGeorge syndrome have developmental disorders such as growth retardation and delayed speech development, and are more likely to have developmental conditions such as attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorders that affect communication and social interaction.

Diagnosis

Prenatal

• FISH・Array CGH methods
• Fetal echocardiography
• Fetal MRI

Postnatal

• CT scan
• MRI
• Echocardiography
• Blood calcium levels
• Monitoring of immune cells
• Genetic testing of patients, siblings and parents (detectable with our microdeletion test)

Treatment

There is no radical treatment. Surgical treatment for cardiovascular abnormalities, treatment of hypocalcaemia, and infection prevention and treatment for immunocompromised conditions are used. Thymic transplantation or haematopoietic stem cell transplantation may be used.

Prognosis

Prognosis is often determined by the severity of cardiac disease, which can be fatal if untreated, but if symptoms are mild, there is no impact on long-term survival if appropriate treatment is given. However, some form of mental retardation/developmental disorder should be considered.