An atypical 0.73 MB microduplication of 22q11.21 and a novel SALL4 missense mutation associated with thumb agenesis and radioulnar synostosis.

Abstract

We describe a 0.73 Mb duplication of chromosome 22q11.21 between LCR-B and LCR-D and a missense mutation in a conserved C2H2 zinc finger domain of SALL4 in a cognitively normal patient with multiple skeletal anomalies including radioulnar synostosis, thumb aplasia, butterfly vertebrae, rib abnormalities, and hypoplasia of the humeral and femoral epiphyses. 22q11.21 is a common site for microdeletions and their reciprocal microduplications as a result of non-allelic homologous recombination between its multiple low copy repeat regions (LCR). DiGeorge /Velocardiofacial syndrome (DG/VCFS) is classically caused by a 3 Mb deletion between LCR-A and LCR-D or a 1.5 Mb deletion between LCR-A and LCR-B. The reciprocal syndrome to DG/VCFS is the recently described 22q11.2 microduplication, which usually presents with the typical 3 Mb or 1.5 Mb duplication. Numerous atypical deletions and duplications have been reported between other LCRs. Typically, SALL4-related Duane-radial ray syndrome is caused by deletions or nonsense mutations; the only missense SALL4 mutation described prior was thought to result in gain of function and produced cranial midline defects. The skeletal anomalies presented in this report have not been previously described in association with 22q11.2 microduplication nor SALL4 mutations.

• Authors: Adam Diehl, Weiyi Mu, Denise Batista, Meral Gunay-Aygun
• Journal: American journal of medical genetics. Part A (Am J Med Genet A) Vol. 167 Issue 7 Pg. 1644-9 (Jul 2015) ISSN: 1552-4833 [Electronic] United States
• PMID: 25823593 (Publication Type: Case Reports, Journal Article, Research Support, N.I.H., Extramural)
• Copyright: © 2015 Wiley Periodicals, Inc.

Chemical References

• SALL4 protein, human
• Transcription Factors

Topics

• Abnormalities, Multiple (genetics, pathology)
• Base Sequence
• Chromosome Disorders (genetics, pathology)
• Chromosome Duplication (genetics)
• Chromosomes, Human, Pair 22 (genetics)
• Hand Deformities (genetics, pathology)
• Humans
• Molecular Sequence Data
• Mutation, Missense (genetics)
• Polymorphism, Single Nucleotide
• Radius (abnormalities, pathology)
• Segmental Duplications, Genomic (genetics)
• Sequence Analysis, DNA
• Synostosis (genetics, pathology)
• Thumb (abnormalities, pathology)
• Transcription Factors (genetics)
• Ulna (abnormalities, pathology)