Interstitial insertion of Y-specific DNA sequences including SRY into chromosome 4 in a 45,X male child.
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.