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A new X‐linked syndrome with agenesis of the corpus callosum, mental retardation, coloboma, micrognathia, and a mutation in the Alpha 4 gene at Xq13
Author(s) -
Graham Jr. John M.,
Wheeler Patricia,
TackelsHorne Darci,
Lin Angela E.,
Hall Bryan D.,
May Melanie,
Short Kieran M.,
Schwartz Charles E.,
Cox Timothy C.
Publication year - 2003
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.20504
Subject(s) - coloboma , short stature , corpus callosum , genetics , corpus callosum agenesis , agenesis of the corpus callosum , biology , haploinsufficiency , choanal atresia , anatomy , atresia , phenotype , endocrinology , gene
We describe two brothers with a unique pattern of malformations that includes coloboma (iris, optic nerve), high forehead, severe retrognathia, mental retardation, and agenesis of the corpus callosum (ACC). Both boys have low‐set cupped ears with sensorineural hearing loss, normal phallus, pectus excavatum, scoliosis, and short stature. One brother had choanal atresia and cardiac defects consisting of ventricular septal defect (VSD) and patent ductus arteriosus (PDA) which resolved spontaneously. Differential diagnosis between a number of clinical entities was considered, however, because ACC and the distinctive facial features were reminiscent of FG syndrome, DNA was analyzed for markers linked to the FGS1 locus at Xq13‐q21. Notably, the brothers were concordant for markers spanning this presumed FG region, and in both we have identified adjacent alterations (−57delT and T‐55A) in the Alpha 4 gene located within this interval. Alpha 4 is a regulatory subunit of the major cellular phosphatase, PP2A, that has recently been shown to interact with MID1, the product of the gene mutated in X‐linked Opitz GBBB syndrome. The double nucleotide change identified in this family was not observed in 410 control chromosomes, suggesting that it may be a pathogenetic change. Altered expression of Alpha 4, through either a change in translational efficiency, mRNA stability or splicing, could explain the clinical phenotype in these boys and the phenotypic overlap with Opitz GBBB syndrome. © 2003 Wiley‐Liss, Inc.