Abstract
Paracentromeric regions of the Y chromosome are essential for determining maleness. Thus DNA probes from this portion of the human Y are preferable for fetal sexing to probes from the heterochromatic, nonessential long arm of the Y. The highly repetitive sequences found at the centromeres of human chromosomes belong to the alphoid repeat family. We have identified human Y cosmids (prepared by cloning DNA from 3E7, a human-mouse hybrid containing Y chromosomes as the only human contribution, and selecting colonies hybridizing to human female genomic DNA) containing the Y alphoid repeat by screening the collection of cosmids with a known alphoid repeat. The sequence found was shown to be Y centromeric by in situ hybridization to metaphase chromosomes and by somatic cell hybrid mapping. Although cross-hybridization to other chromosomes occurs on in situ hybridization (at high stringency, there are 5 times as many grains on the Y as on any other chromosome), restriction enzyme analysis of genomic DNAs disclosed that an EcoRI, 5.3 kb fragment is diagnostic of the Y alphoid sequence. Dosage experiments demonstrated 100 copies of this Y-specific alphoid repeat per Y chromosome. The diagnostic Y chromosomal fragment could be rapidly detected in 50 nanograms of DNA. Thus, this probe will provide prenatal sexing of phenotypic males even in the absence of an intact Y chromosome.
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Erickson, R., Wolfe, J. & Goodfellow, P. 819 AY CENTROMERE REPEAT FOR SEXING FETAL DNA. Pediatr Res 19, 247 (1985). https://doi.org/10.1203/00006450-198504000-00849
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DOI: https://doi.org/10.1203/00006450-198504000-00849