A NEW RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM AT THE DXS101 LOCUS ALLOWS CARRIER DETECTION IN A FAMILY WITH X-LINKED AGAMMAGLOBULINEMIA

The gene responsible for X linked agammaglobulinaemia (XLA) lies in Xq 22 and has recently been identified as atk. DXS101 is a polymorphic lo cus which is closely linked to the disease locus. In this report we de scribe the identification, by pulsed field gel electrophoresis, of a n ew polymorphism at the DXS101 locus with a predicted heterozygosity of 4.9%. Despite this low value, we show how this polymorphism has been important in carrier status determination in a family with XLA where a ssessment was not possible by other means.