Une mère et ses deux filles jumelles univitellines atteintes de chondrodysplasie

Till to-day there are very few concordant and discordant twin pairs known with regard to chondrodysplasy. We describe here a family in which as well the mother as also her both twin daughters are affected with this disturbance of development. The monozygosity of the sisters is beyond all doub

Le mécanisme héréditaire de la maladie de Dupuytren

Dupuytren's disease recurs more frequently than generally assumed. 24 typical family trees derived from the literature are analyzed here. The main conclusions that can be derived are the following: 1) Monogenic heredity is confirmed. 2) The sex ratio in the affected families is 61,2 m: 38,8 f. 3) The sex ratio in unaffected families is 38 m: 43 f. 4) The expressivity of the disease is variable. Penetrance, which is incomplete, varies according to the sex. In our selected material, the penetrance rate is 93,6% in the males and 42,9% in the females. 5) Males transmit the gene in 68% of the cases; females in 32%. 6) Incomplete sex linkage can be excluded. 7) A comparison is made between the really observed values and the theoretical rates for normal and affected men and women for the chance of an auto-somatic dominance. These observations make possible the conclusion that the number of affected females is too low as compared with unaffected females and affected males. 8) A new theory is suggested concerning the mechanism of heredity based on the different statistical values. The responsible factor would be deadly for 60% of the XX affected zygotes. But 60% of the affected X gametes produced by the mother, being identified by an essential incompatibility for the unaffected X spermatozoid, would be electively fecundated by a Y gamate. This machanism would explain the excess of affected males, the small proportion of affected females and the sex-ratio of 61,2: 38,8. The concordance between the observed values and the theoretically expected values of such a kind seem to convalidate our new theor