GERMLINE AND SOMATIC MOSAICISM IN A FEMALE CARRIER OF HUNTER DISEASE

Carrier detection in a mucopolysaccharidosis type II family (Hunter di sease) allowed the identification of germline and somatic mosaicism in the patient's mother: the R443X mutation was found in a varying propo rtion in tested tissue (7% in leucocytes, lymphocytes, and lymphoblast oid cells, and 22% in fibroblasts). The proband's sister carries the a t risk allele (determined by haplotype analysis), but not the mutation . In sporadic cases of X linked diseases, germline mosaicism of the pr oband's mother is difficult to exclude and should be considered in gen etic counselling.