Phenotype and Gamma Globulin Levels

In 1964, de Grouchy described the clinical picture associated with partial monosomy for No. 18 chromosome due to a deletion of part of the long arms (de Grouchy et al., 1964a, b). Subsequent case reports have confirmed a phenotypic similarity in individuals with this deletion. Edwards and associates (1960) described a new autosomal trisomy, that of chromosome 18. Since their report, there have been many similar cases described. However, there have also been several cases reported of partial trisomy for No. 18 chromosome due to translocation of part of this chromosome on to another autosome. We are reporting a family in which there is both a monosomic and a trisomic condition for a portion of the long arms of No. 18 chromosome transmitted through three generations by balanced carriers.