Q90.2 Trisomy 21, translocation

Name of the Condition

• Trisomy 21, translocation

Summary

Trisomy 21, translocation is a genetic form of Down syndrome caused by an extra copy of chromosome 21 attached to another chromosome. This results in developmental delays, intellectual disability, and characteristic physical features.

Causes

The condition occurs when a segment of chromosome 21 breaks off and attaches to another chromosome (usually chromosome 14). This translocation can be inherited from a parent who carries the balanced translocation or occur as a new (de novo) event.

Risk Factors

• Parental carrier status: Individuals with a balanced translocation involving chromosome 21 have a higher risk of passing it to offspring.
• Family history: A parent with a balanced translocation may transmit the condition to their children.

Symptoms

• Distinctive facial features (e.g., flat facial profile, almond-shaped eyes, small ears).
• Developmental and intellectual delays.
• Hypotonia (low muscle tone) and growth delays.
• Increased risk of congenital heart defects and other medical issues.

Diagnosis

Diagnosis is confirmed through chromosomal analysis (karyotyping) to identify the translocation. Prenatal testing (e.g., amniocentesis, chorionic villus sampling) or postnatal testing may be used.

Treatment Options

• Early intervention programs (physical, occupational, speech therapy).
• Regular monitoring for associated health issues (e.g., cardiac, thyroid).
• Educational support and developmental services.

Prognosis and Follow-Up

Prognosis varies based on associated health conditions. Lifelong monitoring for medical complications (e.g., heart disease, hearing loss) and developmental support is often necessary.

Complications

• Congenital heart defects.
• Gastrointestinal abnormalities.
• Hearing and vision problems.
• Increased risk of Alzheimer’s disease later in life.

Lifestyle & Prevention

• Genetic counseling for families with a translocation carrier.
• Prenatal screening options for at-risk pregnancies.
• Supportive care to address developmental and health needs.

When to Seek Professional Help

Seek medical evaluation if developmental delays, characteristic physical features, or health concerns (e.g., heart issues) are observed. Early diagnosis supports timely intervention.

Tips for Medical Coders

Document the specific translocation (e.g., 14;21) when available. Ensure differentiation from other Trisomy 21 subtypes (e.g., nonmosaicism) based on chromosomal analysis. Code Q90.2 is assigned for translocation-type Trisomy 21.