PHELAN-MCDERMID SYNDROME

ALTERNATE NAMES

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

DESCRIPTION

Phelan-McDermid Syndrome is a rare genetic disorder that involves a deletion of 22q13 or a mutation of the SHANK3 gene. The syndrome is generally characterized by neonatal hypotonia (reduced muscle tone), global developmental delay, absent to severely delayed speech, disproportionately large hands/feet, dysplastic toenails, abnormal growth, and decreased perspiration. The signs and symptoms vary widely from person to person. Some children have specific behavior characteristics including mouthing or chewing non-food items, decreased pain perception, and an autistic-like affect.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING

Diagnostic testing: Molecular genetic testing (usually chromosome microarray analysis, or CMA), or fluorescent in situ hybridization (FISH) test analysis documenting the chromosome 22q13.3 deletion or sequencing documenting a mutation of SHANK3..

Physical findings: (see above)

ICD-9: 758.39

ONSET AND PROGRESSION

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.

TREATMENT

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:

• Clinical history and examination that describes the diagnostic features of the impairment and laboratory findings are needed to confirm the diagnosis.

• Developmental assessment or psychological testing to address allegations of mental impairment may be warranted.

Suggested Listings for Evaluation:

DETERMINATION

LISTING

REMARKS

Meets Listing

12.05

12.10

112.05

112.10

112.14

In all cases determined on the basis of a 12.00/112.00 mental disorders listing, evidence must establish listing-level limitations in functioning according to the paragraph B or paragraph C criteria of the listing, or according to the requirements of 12.05/112.05 or 112.14, as applicable.

Medical Equals