Cytogenomic and phenotypic analysis in low-level monosomy 7 mosaicism with non-supernumerary ring chromosome 7

Am J Med Genet A. 2014 Jul;164A(7):1765-9. doi: 10.1002/ajmg.a.36503. Epub 2014 Mar 26.


We present the literature review of ring chromosome 7 and clinical, cytogenetic and fine molecular mapping of the first postnatal report of a male child with a non-supernumerary ring chromosome 7, r(7). The patient had dysmorphic features, developmental delay, dermatologic lesions with variable pigmentation, hypogenitalism, lumbar dextroscoliosis, cerebellar and ophthalmological abnormalities, and melanocytic congenital nevi. Cytogenetic analysis of peripheral blood and the nevus sample showed the presence of three different cell lines r(7), monosomy 7, and duplicated r(7) (idic r(7)), while findings on fibroblasts from both light and dark skin showed only mosaicism with r(7) and monosomy 7 cell lines in various proportions. FISH assay of the ring chromosome showed subtelomeric loss in both chromosome arms in all tissues studied. Analysis by genome-wide single-nucleotide polymorphism array showed a 0.8 Mb deletion in 7p22.3 (involving eight genes) and a 7.5 Mb deletion in 7q36 (involving 29 genes including some involved in genital and central nervous system development). The combination of results from our karyotypic and array analyses enabled us to establish an accurate genotype-phenotype relationship.

Keywords: deletion 7p22.3; deletion 7q36.1; monosomy 7 mosaicism; ring chromosome 7.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Chromosome Banding
  • Chromosome Disorders / diagnosis*
  • Chromosome Disorders / genetics*
  • Chromosomes, Human, Pair 7 / genetics
  • Comparative Genomic Hybridization
  • Cytogenetic Analysis*
  • Genetic Association Studies
  • Humans
  • In Situ Hybridization, Fluorescence
  • Infant
  • Male
  • Mosaicism*
  • Phenotype*
  • Ring Chromosomes

Supplementary concepts

  • Chromosome 7 ring syndrome