[Prenatal diagnosis in parents with a balanced structural chromosome aberration (author's transl)]

Familial Wolf's syndrome with a hidden 4p deletion by translocation of an 8p segment. Unbalanced inheritance from a maternal translocation (4;8)(p15.3;p22). Case report, review and risk estimates

This is the case report of a patient with Wolf's syndrome having a monosomy 4pter----p15.3 and an additional trisomy 8pter----p22, derived from a maternal balanced translocation t(4;8)(p15.3;p22) after 2:2 disjunction and adjacent-1 segregation. The patient's phenotype is presumably slightly modified by the trisomic 8p segment. Literature analyses indicate that phenotypic "hybrids" with traits of monosomy 4p and of other autosomal segment trisomies exist. The dermatoglyphics of the patient were not highly characteristic for Wolf's syndrome. Also the dermatoglyphics of the balanced translocation carriers were unspecific and did not reflect the carrier status. Pedigree analyses of 46 reported families with reciprocal translocations involving the short arm of chromosome 4 show a high risk (20.5% +/- 4.6%) for unbalanced offspring (trisomy or monosomy 4p) after 2:2 disjunction and adjacent-1 segregation, if the breakpoint in the recipient chromosome is terminal and the resulting imbalance concerns the 4p segment only. It is considerably lower (4.5% +/- 2.5%) if the breakpoint in the recipient chromosome is subterminal, as in the reported case, and the resulting imbalance concerns other chromosome segments additionally to the 4p segment. In both instances, the risk decreases with increasing segment length. The risk for unidentified abortions, stillbirths or neonatal deaths is also high in these families (about 40%). The frequency of progeny with balanced compared to progeny with normal karyotype corresponds to the expected 50% for alternate segregation.