Phelan-McDermid syndrome

This code identifies Phelan-McDermid syndrome, a neurodevelopmental disorder caused by a deletion on chromosome 22q13.33 or a pathogenic variant in the SHANK3 gene. It is characterized by intellectual disability, absent or severely delayed speech, hypotonia, and often features of autism spectrum disorder.

Assign this code for patients definitively diagnosed with Phelan-McDermid syndrome, typically confirmed through genetic testing. Documentation should clearly state the diagnosis of Phelan-McDermid syndrome, often noting the 22q13.33 deletion or SHANK3 gene mutation.

• Do not confuse with other chromosomal abnormalities or syndromic intellectual disabilities without specific genetic confirmation of Phelan-McDermid.
• Code any associated manifestations, such as intellectual disabilities (F70-F79), autism spectrum disorders (F84.0), or epilepsy (G40.-), as secondary diagnoses.
• Ensure genetic testing results or a confirmed clinical diagnosis by a geneticist or neurologist are present in the medical record.