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Approximately 1 of 500 individuals is a carrier of a balanced chromosome translocation. Since many translocations are inherited, many (but not all) relatives of carriers have a need to be informed of their potential carrier status. Presently, no data are available as to what extent individuals identified as balanced carriers inform at-risk relatives of the problem. We interviewed 12 balanced translocation carriers to learn whether such information had been transmitted to relatives. The 12 propositi had 36 surviving sibs and 21 surviving parents. Of the 36 sibs, 32 were informed of their risk. The four sibs not informed were from two families. Only 16 of the 32 informed sibs had subsequent carrier testing. Of the 21 surviving parents, 14 were told by their children of their carrier status; subsequently, three parent couples were tested. This survey provides data showing that individuals do not always disclose genetic risk information to relatives. Therefore, genetic professionals need to determine if they have a duty to transmit such information to at-risk relatives in light of the harm that may occur when information is withheld.

A newborn male was diagnosed as having a duplication of distal 9p material by GTG banding analysis. Gene dose studies for galactose-1-phosphate uridyl transferase (GALT) were performed on the patient, his mother (the balanced translocation carrier), a 3-year-old 47,XY + 9p male control, a 30-year-old woman with mosaic trisomy 9p, a newborn female control infant with complete trisomy 9, and age-matched chromosomally normal control individuals. The findings support previous evidence that the GALT locus is at band p13 of chromosome 9.

A 45,X chromosome complement was found in the lymphocytes and skin fibroblast cultures of a male infant with minor facial anomalies and gastrointestinal abnormalities. Fluorescence in situ hybridization (FISH) studies with DNA probes specific for the entire Y chromosome (painting) and SRY identified insertion of a short piece of Y chromosome DNA, including the SRY region, into a der(4) chromosome at 4p15. FISH studies with DNA probes specific for Wolf-Hirschhorn syndrome (WHS) and telomere of 4p indicated that these 2 regions were intact and that the insertion of Y DNA had occurred proximal to the WHS region. High-resolution chromosome analysis performed after FISH studies showed an altered banding pattern of 4p at the region of insertion. The typical Giemsa dark band of 4p15 was consistently replaced by a gray band; this probably indicates deletion of the distal part of 4p15. The consequences of the double-chromosome anomaly in this patient were discussed in relation to his phenotype.