ADDITIONAL EVIDENCE FOR FRAGILE-X ACTIVITY IN HETEROZYGOUS CARRIERS

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  • 1 January 1983
    • journal article
    • research article
    • Vol. 35  (5) , 861-868
Abstract
A study showing an association between mental development and fragile X activity in heterozygous females is given further support by similar investigations of 3 additional kindreds. The increased frequency of demonstrable fragile X chromosomes in mentally retarded females appears to be due to an increase in the active fragile X while the inactive marker X remains at a similar low frequency in all heterozygotes whether retarded or not. The frequencies of the active fragile X separated the normal and abnormal subjects into 2 distinct populations. The suggested inverse correlation between the number of lymphocytes with detectable fragile X chromosomes and advancing age can be attributed to ascertainment biases.