7018. Karyotyping (blood, DiGeorge syndrome, GTG- and FISH-methods)

DiGeorge syndrome is a genetic disorder caused by a microdeletion of the 22q11.2 region. It presents with immunodeficiency, hypocalcemia, and heart defects. Diagnosis is made using karyotyping with the GTG and FISH methods.

DiGeorge syndrome (del22q11.2) results from a deletion of part of the long arm of chromosome 22. The disorder is caused by developmental abnormalities in the tertiary and quaternary branchial sac derivatives, leading to:

• thymic hypoplasia/aplasia (congenital immunodeficiency);
• parathyroid hypoplasia (hypocalcemia, seizures);
• congenital heart defects (most commonly, aortic arch interruption and ventricular septal defects);
• specific facial features;
• psychomotor retardation;
• increased susceptibility to infections.

In 90-95% of cases, the deletion occurs de novo, but in 5-10%, it is inherited. Diagnosis is made using GTG karyotyping and FISH analysis, which allows for the identification of 22q11.2 microdeletion with high accuracy, even when standard karyotyping is ineffective.

• Prenatal diagnosis – based on biochemical or ultrasound screening results that indicate heart defects, thymus shrinkage, and other developmental anomalies.
• Postnatal diagnosis – in cases of developmental delay, hypocalcemia, immunodeficiency conditions, and cardiomyopathy.
• For parents of a child with confirmed DiGeorge syndrome – to determine hereditary risks in subsequent pregnancies.
• When planning a pregnancy – if there is a family history of microdeletion syndromes or congenital defects.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: