Phelan-McDermid Disease; Deletion 22q13 Syndrome; 22q13 Deletion Syndrome; Chromosome 22q13.3 Syndrome; Monosomy 22q13; Deletion 22q13.3 Syndrome

Phelan-McDermid Syndrome is a rare genetic disorder that involves a deletion of 22q13 or a mutation of the SHANK3 gene.

Diagnostic testing:

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  Molecular genetic testing (usually chromosome microarray analysis, or CMA); or

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  Fluorescent in situ hybridization (FISH) test analysis.

Physical findings: The syndrome is generally characterized by:

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  Neonatal hypotonia (reduced muscle tone);

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  Global developmental delay;

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  Absent to severely delayed speech;

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  Disproportionately large hands/feet;

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  Dysplastic toenails;

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  Abnormal growth; and

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  Decreased perspiration.

The signs and symptoms vary widely from person to person. Some children have specific behavior characteristics including:

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  Mouthing or chewing non-food items;

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  Decreased pain perception; and

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  An autistic-like affect.

ICD-9: 758.39

Individuals with Phelan-McDermid syndrome generally have life-long complications associated with this disorder with no apparent life-threatening organic malformations. Individuals surviving to adulthood may not be able to function independently and may require supportive services.

There is no cure for this disorder. Treatment is supportive and symptom specific. Physical and occupational therapies are utilized to improve adaptive functioning and strengthen muscles; and speech/language therapy is used to address delayed speech and language development. School age children require individualized and flexible instructional criteria.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Clinical history and examination that describes the diagnostic features of the impairment;

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  Laboratory findings documenting the chromosome 22q13.3 deletion or sequencing documenting a mutation of SHANK3 (CMA or FISH testing); and

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  Developmental assessment or psychological testing..

REMARKS