Determining the origin of human X isochromosomes by use of DNA sequence polymorphisms and detection of an apparent i(Xq) with Xp sequences

✍ Scribed by David F. Callen; John C. Mulley; Elizabeth G. Baker; Grant R. Sutherland

• Book ID: 104704455
• Publisher: Springer
• Year: 1987
• Tongue: English
• Weight: 777 KB
• Volume: 77
• Category: Article
• ISSN: 0340-6717
• DOI: 10.1007/bf00284476

✦ Synopsis

The parental origin of five X isochromosomes were determined using 11 DNA markers. The isochromosome was derived from a maternal X chromosome in three cases and from a paternal X chromosome in two. Unexpected heterozygosity was detected for the proximal Xp region in one individual in whom the i(Xq) chromosome was paternally derived. This was confirmed by in situ hybridisation. A mode of formation of isochromosomes by breakage and reunion between the sister chromatids of the arms of an X chromosome is proposed to account for this. Sister chromatid breakage and reunion can be considered as a significant mechanism for the origin of i(Xq) chromosomes.