Q90.0

Clinical Causes: Meiotic nondisjunction during egg development, resulting in an extra chromosome 21 in the fertilized egg. Failure of chromosome 21 to separate properly during the formation of the egg or sperm. It is not typically inherited but occurs due to random errors in cell division.

Key Symptoms: Distinct facial features, including a flat facial profile, almond-shaped eyes that slant upwards, and a small nose. Low muscle tone (hypotonia) in infancy. Short stature and slower growth rates. A single deep crease across the palm of the hand (simian crease). Developmental delays and intellectual disabilities. Possible health issues such as heart defects, hearing problems, and vision impairments. Increased risk of gastrointestinal issues, such as intestinal blockage (atresia). Variations in immune system functioning, leading to increased susceptibility to infections.

Diagnosis Path: Diagnosis can be made prenatally through screening tests such as ultrasound and blood work, followed by confirmatory diagnostic tests like chorionic villus sampling (CVS) or amniocentesis, which analyze fetal chromosomes. After birth, a physical examination and a karyotype test—examining chromosomes under a microscope—are used to confirm the diagnosis and detect the presence of an extra chromosome 21.

Treatment Protocols: Developmental therapies, including physical, occupational, and speech therapy. Regular health monitoring to identify and treat health problems early. Educational support tailored to individual needs. Management of specific health issues such as heart defects or thyroid problems. Inclusive community support and specialized educational programs.