title: A 45,X male with a Yp/18 translocation.
abstract: A patient described as a 45,X male (Forabosco et al. 1977) was examined for the presence of Y-specific DNA by using various probes detecting restriction fragments from different regions of the Y chromosome. Positive hybridization signals were obtained for Yp fragments only. In situ hybridization with two different probes, pDP31 and the pseudoautosomal probe 113F, led to a clear assignment of the Yp sequences to the short arm of one chromosome 18. Cytogenetically, the presence of all of Yp including the Y centromere on 18p could be demonstrated replacing a segment of similar size of 18p. Thus, the Y/18 translocation chromosome is dicentric structurally, but it was shown to be monocentric functionally with the no. 18 centromere active. Gene dosage studies with the probe B74 defining a sequence at 18p11.3 demonstrated a single dose of this sequence in the patient. In agreement with these observations, the patient shows clinical signs of the 18p-syndrome. It is concluded that in XO males in general, the X is of maternal origin while the maleness is due to a de novo Y/autosome translocation derived from the father. Depending on the nature of the autosomal deficiency caused by the Y/autosome translocation, the patient may have congenital malformations.
mesh_terms: D002648:Child; D002871:Chromosome Banding; D002887:Chromosomes, Human, Pair 18; D004247:DNA / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D008297:Male; D009634:Noonan Syndrome / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D012150:Polymorphism, Restriction Fragment Length; D014178:Translocation, Genetic; D014998:Y Chromosome
chemical_list: D004247:DNA