J Genet Med.  2017 Dec;14(2):62-66. 10.5734/JGM.2017.14.2.62.

Prenatal diagnosis of interchromosomal insertion of Y chromosome heterochromatin in a family

Affiliations
  • 1Laboratory of Medical Genetics, Cheil General Hospital and Women's Healthcare Center, Seoul, Korea.
  • 2Department of Obstetrics and Gynecology, Cheil General Hospital and Womens Healthcare Center, Dankook University College of Medicine, Seoul, Korea. c1loveya@naver.com

Abstract

Interchromosomal insertion of Y chromosome heterochromatin in an autosome was identified in a fetus and a family. A fetal karyotype was analyzed as 46,XX,dup(7)(?q22q21.1) in a referred amniocentesis at 16 weeks of gestation for advanced maternal age. In the familial karyotype analyses for identification of der(7), the mother, the first daughter and the maternal grandmother showed the same der(7) as the fetus's. CBG-banding was positive at 7q22 region of der(7) that indicated inserted material was originated from heterochromatin. The origin of heterochromatic insertion region in der(7) of the fetus and the mother was found in Yq12 region by fluorescent in situ hybridization with a DYZ1 probe. In the specific analysis of Y chromosomal heterochromatic region of ins(7;Y) of the mother, 15 sequence tagged sites from Yp11.3 region including SRY to Yq11.223 region was not detected. Final karyotypes of the mother, the first daughter and the maternal grandmother were reported as 46,XX,der(7)ins(7;Y)(q21.3;q12q12). All female carriers of ins(7;Y) in the family showed normal phenotype and the mother and the maternal grandmother were fertile. A healthy girl was born at term. We report a rare case of familial interchromosomal insertion of Y chromosome heterochromatin detected only in female family members with normal phenotype that was diagnosed prenatally.

Keyword

Insertion; Y chromosome; Heterochromatin; Prenatal diagnosis
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