Coexistence of a Homozygous Chromosome 4q35.2 Deletion and Hidden IQSEC2 Pathogenic Variant in a Child with Intellectual Disability

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Karaman Mercan T., Altıok Clark Ö., Erkal O., Nur B., Mıhçı E., Karaman B., ...More

CYTOGENETIC AND GENOME RESEARCH, vol.161, no.3-4, pp.153-159, 2021 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 161 Issue: 3-4
  • Publication Date: 2021
  • Doi Number: 10.1159/000515368
  • Journal Name: CYTOGENETIC AND GENOME RESEARCH
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, BIOSIS, CAB Abstracts, EMBASE, MEDLINE, Veterinary Science Database
  • Page Numbers: pp.153-159
  • Keywords: Deletion 4q35, 2, Homozygous deletion, IQSEC2 gene, Subtelomeric FISH, Whole-exome sequencing, TERMINAL DELETION, KIDNEY, GENE, 4Q
  • Akdeniz University Affiliated: Yes

Abstract

Terminal deletions in the long arm of chromosome 4 are an uncommon event, with a worldwide incidence of approximately 0.001%. The majority of these deletions occur de novo. Terminal deletion cases are usually accompanied by clinical findings that include facial and cardiac anomalies, as well as intellectual disability. In this study, we describe the case of a 2-year-old girl, the fourth child born to consanguineous parents. While her karyotype was normal, a homozygous deletion was identified in the chromosome 4q35.2 region by subtelomeric FISH. A heterozygous deletion of the chromosome 4q35.2 region was observed in both parents. According to the literature, this is the first report of a case that has inherited a homozygous deletion of chromosome 4qter from carrier parents. Subsequent array-CGH analyses were performed on both the case and her parents. Whole-exome sequencing was also carried out to determine potential variants. We detected a NM_001111125.3:c.2329G>T (p.Glu777Ter) nonsense variant of the IQSEC2 gene in the girl, a variant that is related to X-linked intellectual disability.