An analysis procedure illustrated on a triple linkage of use for prenatal diagnosis of myotonic dystrophy.

Abstract

Diagnosis of a number of simple genetic con- ditions in man is now feasible prenatally For those simple genetic con- ditions that cannot be so diagnosed by direct means, indirect diagnosis through the prenatal phenotype for a marker locus known to be linked to the disease locus (Edwards, 1956; Renwick, 1969), is a useful substitute with potentially wide applicability. A special case is the use, in certain families, of the chromosomal sex of the embryo to give a 50% or 0% prognosis of haemophilia for male and female respectively. Attention is now drawn to an auto- somal linkage between the myotonic dystrophy locus (Dm) and the ABH secretor locus (Se) that can be used in favourable circumstances to predict fairly accurately the outcome of a particular preg- nancy in a family with this dystrophy.