Familial translocation t(3p-;21q+) associated with both Down's and Sturge-Weber's syndrome in unbalanced state.

A boy with both Down's and Sturge-Weber's syndrome was found to have a partial trisomy 21 as a consequence of a familial translocation t(3p-;21q+) which is not reciprocal. Judging from the structure of the involved chromosomes studied by banding and photometrical techniques, the loss of relatively large material of 21q is to be suggested. The meiotic segregation appears to depend on the involved 3p segment and not on the involved centromere of No. 21 as actually expected. The pedigree of the family shows 6 balanced carriers through 3 generations in addition to the propositus. The risk of having offspring with Down's syndrome obviously concerns female carriers in the first place, whereas the male carriers rather produce balanced carriers. Of the additional Sturge-Weber's syndrome there was no cytogenetical cause as expected.