Human Cytogenetics Case Report Yet Unreported Heteromorphic Variantin Chromosome 17
Background: Heteromorphic variants including Yq12 material, being inserted or added to autosomal chromosomes have been reported for chromosomes 1, 7, 11, 13, 14, 15, 21 and 22. Here we describe a novel insertion of Yq12 heterochromatin into a chromosome 17; to the best of our knowledge no similar cases have been reported previously. Methods: GTG-, C-banding, fluorescence in situ hybridization (FISH), and homemade human heterochromatin specific multicolor FISH probes set (HCM-mix) were used to define the abnormality. A whole chromosome painting (wcp) probe for #17 together with a probe for Yq12 heterochromatin was hybridized to the patient sample. Additionally, Y microdeletion PCR was done to detect possible AZF subregional deletions. Results: The male patient had normal sperm analysis and no AZF deletions on Y chromosome. GTG and Cbanding showed an additional band on chromosome 17q21. FISH studies revealed that the insertion was derived from Yq12 heterochromatin. Conclusions: The heterochromatin insertion on 17q21 originating from Yq12 chromosome did not affect the spermatogenesis of aberration carrier and is probably not the cause of infertility in these partners. However, a new heteromorphic variant was identified in this case.