ABSTRACT
We report a 4-generation Hispanic family with oculodentodigital dysplasia whose members were found to have typical phenotypic characteristics of this disorder, as well as a variable expression of neurologic manifestations in multiple generations ranging from a mild spastic gait to moderate to severe spastic tetraparesis/quadriplegia with epilepsy and an abnormal brain and spinal cord magnetic resonance imaging result. Gene testing documented a previously reported missense mutation in GJA1 (connexin 43) exon 2 (c.389T>C;p.I130T). Our evaluation not only expands the phenotypes associated with GJA1 gene mutations but also demonstrates that a great degree of variability in neurological defects can exist within a single family without evidence of genetic anticipation. A genotype-phenotype correlation between the p.I130T mutation and neurologic dysfunction appears more likely with the addition of this report's neurologic and GJA1 gene mutation findings. These findings expand the neurologic phenotype and prognosis and underscore the importance of counseling families with oculodentodigital dysplasia about the possibility of neurologic involvement.
Subject(s)
Abnormalities, Multiple/genetics , Connexin 43/genetics , Craniofacial Abnormalities/genetics , Eye Abnormalities/genetics , Neurologic Examination , Phenotype , Syndactyly/genetics , Tooth Abnormalities/genetics , Abnormalities, Multiple/diagnosis , Adolescent , Adult , Aged , Brain/pathology , Child , Chromosome Aberrations , Craniofacial Abnormalities/diagnosis , Exons/genetics , Eye Abnormalities/diagnosis , Female , Gait Disorders, Neurologic/diagnosis , Gait Disorders, Neurologic/genetics , Genes, Dominant/genetics , Genetic Counseling , Genotype , Humans , Magnetic Resonance Imaging , Male , Mutation, Missense , Paraplegia/diagnosis , Paraplegia/genetics , Pedigree , Penetrance , Prognosis , Quadriplegia/diagnosis , Quadriplegia/genetics , Spinal Cord/pathology , Syndactyly/diagnosis , Tooth Abnormalities/diagnosisABSTRACT
Split-hand/foot malformation (SHFM), or ectrodactyly, is characterized by underdeveloped or absent central digital rays, clefts of the hands and feet, and variable syndactyly of the remaining digits. SHFM occurs as both an isolated finding and a component of many syndromes. SHFM is a heterogeneous condition caused by multiple loci, including SHFM1 (chromosome region 7q21-q22), SHFM2 (Xq26), SHFM3 (10q24), SHFM4 (3q27), and SHFM5 (2q31). Mutations in TP63 at the SHFM4 locus are known to underlie both syndromic and non-syndromic forms SHFM, but the causes of most non-syndromic SHFM cases remain unknown. The recent identification of submicroscopic tandem chromosome duplications affecting the SHFM3 locus in seven families with non-syndromic SHFM has helped to further unravel the molecular basis of this malformation. In our ongoing studies of the SHFM3 locus in 44 additional cases of syndromic and non-syndromic SHFM, we have identified similar chromosome rearrangements in eight additional cases (18%), using pulsed-field gel electrophoresis (PFGE). We have also utilized real-time quantitative PCR (qPCR) to test for the duplications. Seven of the cases with rearrangements were non-syndromic. The current findings bring the total of SHFM3-associated cases with chromosome rearrangements to 15, which constitute 29% (15 of 51) of the cases screened to date. This includes 9 of 9 cases (100%) with known linkage to the SHFM3 locus, all of whom have non-syndromic SHFM, and 6 of 42 additional cases (14%), four of whom have non-syndromic SHFM. Thus, SHFM3 abnormalities underlie a substantial proportion of SHFM cases and appear to be a more frequent cause of non-syndromic SHFM than mutations in TP63.
