PATERNAL TRANSMISSION OF CONGENITAL MYOTONIC-DYSTROPHY

We report a rare case of paternally transmitted congenital myotonic dy strophy (DM). The proband is a 23 year old, mentally retarded male who suffers severe muscular weakness. He presented with respiratory and f eeding difficulties at birth. His two sibs suffer from childhood onset DM. Their late father had the adult type of DM, with onset around 30 years. Only six other cases of paternal transmission of congenital DM have been reported recently. We review the sex related effects on tran smission of congenital DM. Decreased fertility of males with adult ons et DM and contraction of the repeat upon male transmission contribute to the almost absent occurrence of paternal transmission of congenital DIM. Also the fathers of the reported congenitally affected children showed, on average, shorter CTG repeat lengths and hence less severe c linical symptoms than the mothers of children with congenital DM. We c onclude that paternal transmission of congenital DM is rare and prefer entially occurs with onset of DM past 30 years in the father.