TY - JOUR
T1 - In-frame multi-exon deletion of SMC1A in a severely affected female with Cornelia de Lange Syndrome
AU - Hoppman-Chaney, Nicole
AU - Jang, Jin Sung
AU - Jen, Jin
AU - Babovic-Vuksanovic, Dusica
AU - Hodge, Jennelle C.
PY - 2012/1
Y1 - 2012/1
N2 - Cornelia de Lange Syndrome (CdLS) is a genetically heterogeneous disorder characterized by dysmorphic facial features, cleft palate, limb defects, growth retardation, and developmental delay. Approximately 60% of patients with CdLS have an identifiable mutation in the NIPBL gene at 5p13.2. Recently, an X-linked form of CdLS with a generally milder phenotype was attributed to mutation of the structural maintenance of chromosomes 1A gene (SMC1A) at Xp11.22. Relatively few CdLS patients with mutations in SMC1A are known; female carriers have minor facial dysmorphism and cognitive deficiency without major structural abnormalities. To date, all mutations identified in SMC1A are missense or small in-frame deletions that preserve the open reading frame of the gene and likely have a dominant-negative effect. We report on a female with monosomy X mosaicism and a phenotype suggestive of a severe form of CdLS who presented with growth and mental retardation, multiple congenital anomalies, and facial dysmorphism. Array CGH confirmed mosaic monosomy X and identified a novel deletion of SMC1A spanning multiple exons, suggesting a possible loss-of-function effect. Sequencing of both genomic and cDNA demonstrated an 8,152bp deletion of genomic DNA from exon 13 to intron 16. Although a loss-of-function effect cannot be excluded, the resulting mRNA remains in-frame and is expressed in peripheral blood lymphocytes, suggesting a dominant-negative effect. We hypothesize that the size of this deletion compared to previously reported mutations may account for this patient's severe CdLS phenotype. The presence of mosaic monosomy X may also modify the phenotype.
AB - Cornelia de Lange Syndrome (CdLS) is a genetically heterogeneous disorder characterized by dysmorphic facial features, cleft palate, limb defects, growth retardation, and developmental delay. Approximately 60% of patients with CdLS have an identifiable mutation in the NIPBL gene at 5p13.2. Recently, an X-linked form of CdLS with a generally milder phenotype was attributed to mutation of the structural maintenance of chromosomes 1A gene (SMC1A) at Xp11.22. Relatively few CdLS patients with mutations in SMC1A are known; female carriers have minor facial dysmorphism and cognitive deficiency without major structural abnormalities. To date, all mutations identified in SMC1A are missense or small in-frame deletions that preserve the open reading frame of the gene and likely have a dominant-negative effect. We report on a female with monosomy X mosaicism and a phenotype suggestive of a severe form of CdLS who presented with growth and mental retardation, multiple congenital anomalies, and facial dysmorphism. Array CGH confirmed mosaic monosomy X and identified a novel deletion of SMC1A spanning multiple exons, suggesting a possible loss-of-function effect. Sequencing of both genomic and cDNA demonstrated an 8,152bp deletion of genomic DNA from exon 13 to intron 16. Although a loss-of-function effect cannot be excluded, the resulting mRNA remains in-frame and is expressed in peripheral blood lymphocytes, suggesting a dominant-negative effect. We hypothesize that the size of this deletion compared to previously reported mutations may account for this patient's severe CdLS phenotype. The presence of mosaic monosomy X may also modify the phenotype.
KW - Cornelia de Lange Syndrome
KW - Dominant negative
KW - Multi-exon deletion
KW - SMC1A
KW - Turner syndrome
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U2 - 10.1002/ajmg.a.34360
DO - 10.1002/ajmg.a.34360
M3 - Article
C2 - 22106055
AN - SCOPUS:84355161987
SN - 1552-4825
VL - 158 A
SP - 193
EP - 198
JO - American Journal of Medical Genetics, Part A
JF - American Journal of Medical Genetics, Part A
IS - 1
ER -