Hypopigmentation in the Prader-Willi syndrome.
Cutaneous and ocular pigmentation were evaluated in 29 individuals with the Prader-Willi syndrome ( PWS ) . Criteria for hypopigmentation included the presence of type I or II skin , the lightest skin type in the family by history , and iris translucency on globe transillumination . On the basis of these criteria , 48 % of the PWS individuals were hypopigmented . The presence of hypopigmentation correlated with a small interstitial deletion on the proximal long arm of chromosome 15 ; however , this deletion was also found in individuals who did not meet the full criteria for hypopigmentation . Hairbulb tyrosinase activity and glutathione content , as well as urine cysteinyldopa excretion , were low in PWS individuals with and without hypopigmentation and did not separate these two groups . We conclude that hypopigmentation is found in a significant proportion of individuals with PWS and that the hypopigmentation may be associated with a deletion of the long arm of chromosome 15 . The mechanism for the hypopigmentation is unknown . .
