PRADER-WILLI-LIKE-SYNDROME IN A PATIENT WITH AN XQ23Q25 DUPLICATION

We report on a 24-year old woman with an Xq duplication and findings s uggestive of Prader-Willi syndrome (PWS), Her birth weight was at the 3rd centile and her birth length was less than the 3rd centile, She wa s hypotonic and had a weak cry as an infant. There were no feeding dif ficulties, although her mother reports that as an infant, she was ''sm all for her age.'' Excessive weight gain began between 3 and 4 years, The patient's development was delayed and she received special educati on. She has a history of hiding food. She has a sleep disturbance diso rder and inappropriate social behavior. At the age of 24 years her hei ght was below the 5th centile and weight >>95th centile, She has physi cal findings typical of PWS, skin picking, and speech articulation def ects. Cytogenetic analysis showed a 46,X,dup(X)(q23q25) karyotype, Flu orescent in situ hybridization (FISH) studies using a chromosome X pai nting probe demonstrated that the rearrangement was intrachromosomal, The X-chromosome fold scoring technique was used to determine the X in activation pattern and indicated that some cells expressed the abnorma l X chromosome. Results of FISH studies using the SNRPN probe localize d to 15q11q13 and DNA studies using the PW71B and SNRPN probes were no rmal. The duplicated X chromosome, random X inactivation pattern, and the negative molecular studies for PWS indicate that the abnormal X ch romosome is the basis of this patient's phenotype, This patient emphas izes the importance of obtaining a karyotype even when a syndrome diag nosable by molecular methods is strongly suspected. (C) 1998 Wiley-Lis s, Inc.