Phelan-McDermid syndrome
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A toddler with autism, absent speech, and global developmental delay has hypotonia and a high pain tolerance. CMA reveals a 22q13.3 deletion.
22q13.3 deletion or SHANK3 variant
- Autism spectrum disorder
- Severe speech delay/absent speech
- Intellectual disability
- Hypotonia, high pain tolerance
- Tendency to chew/mouth objects
- Risk of regression, bipolar disorder in adolescence/adulthood
- CMA detects the 22q13.3 (terminal) deletion; sequencing identifies intragenic SHANK3 variants when CMA is normal
- FISH or parental studies to assess for a ring chromosome 22 or unbalanced translocation when a deletion is found
- Evaluate associated anomalies: renal ultrasound, echocardiogram, audiology, and ophthalmology
- Developmental support: speech, occupational, and physical therapy; augmentative communication for absent speech
- Behavioral and psychiatric monitoring for regression and mood disorder in adolescence/adulthood
- Renal, cardiac, and dental surveillance; lymphedema monitoring; manage hypotonia and high pain threshold (occult injury risk)
- Genetic counseling, including parental karyotype/FISH when a ring 22 or translocation is identified
- Phelan-McDermid loses "Pheeling (feeling) in the Dermis (skin)" → high pain tolerance.
- A Shank can pierce your Dermis