Trisomy 13, nonmosaicism (meiotic nondisjunction)

This code represents Patau syndrome, a severe chromosomal disorder caused by the presence of an extra copy of chromosome 13 in all cells of the body. It results from meiotic nondisjunction, meaning the chromosomes failed to separate properly during the formation of egg or sperm. Infants with Trisomy 13 typically present with multiple congenital anomalies affecting various organ systems.

Use this code for the definitive diagnosis of nonmosaic Trisomy 13, often identified through prenatal genetic testing (e.g., amniocentesis, chorionic villus sampling) or postnatal karyotyping. Documentation should clearly state "Trisomy 13" and specify "nonmosaic" or indicate that it is due to "meiotic nondisjunction."

• Ensure documentation specifies "nonmosaic" to differentiate from mosaic forms of Trisomy 13.
• Code all associated congenital anomalies and malformations separately, as they are not inherent to the Q91.4 code itself.
• Do not confuse with Q91.0 (Trisomy 18, nonmosaicism) or Q91.7 (Trisomy 13, mosaicism).