Genetic prediction in X-linked agammaglobulinaemia.

S21 (DXS17) and pXG12 (DXS94), two probes linked to the locus of X-linked agammaglobulinaemia (XLA), were used for genetic prediction in 13 such families. A method of allowing for nonallelic genetic heterogeneity was demonstrated in the calculation of the genetic risks, specifying a certain proportion of unlinked families. We further estimated the impact due to the uncertainty of the proportion of unlinked families on the final genetic risks in each family and this can be taken into account during genetic counselling.