The true prevalence of PMS has not been determined. More than 1,200 people have been identified worldwide according to the Phelan–McDermid Syndrome Foundation. However, it is believed to be underdiagnosed due to inadequate genetic testing and lack of specific clinical features. It is known to occur with equal frequency in males and females. Studies using chromosomal microarray for diagnosis indicate that at least 0.5% of cases of ASD can be explained by mutations or deletions in the SHANK3 gene. In addition, when ASD is associated with ID, SHANK3 mutations or deletions have been found in up to 2% of individuals.
22q13 deletion syndrome
13q deletion syndrome
2q37 deletion syndrome
22q11.2 distal deletion syndrome
9q34 deletion syndrome
1q21.1 deletion syndrome
1p36 deletion syndrome
22q11.2 duplication syndrome