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Phelan-McDermid Syndrome

Abstract

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NORD is very grateful to M.C. Phelan, MD, of the Molecular Pathology Laboratory, Maryville, Tennessee, for assistance in the preparation of this report.

Synonyms of Phelan-McDermid Syndrome

Deletion 22q13 Syndrome

Disorder Subdivisions

No subdivisions found.

General Discussion

Phelan-McDermid syndrome is a rare chromosomal disorder in which a portion of the long arm (q) of chromosome 22 is missing (deleted or monosomic). Although the range and severity of symptoms may vary, Phelan-McDermid syndrome is generally thought to be characterized by low muscle tone, normal to accelerated growth, absent to severely delayed speech, moderate to profound mental retardation, and minor dysmorphic features. A rare number of cases with much smaller (submicroscopic) deletions of 22q13 are reported to result in mild developmental delay. Current research indicates that the inability of the gene involved to produce sufficient protein for normal functioning (haploinsufficiency) may be responsible for most of the neurologic symptoms (developmental delay and absent speech) associated with this disorder.

Organizations related to Phelan-McDermid Syndrome

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