Time filter

Source Type

Reis L.M.,Medical College of Wisconsin | Khan A.,Al Shifa Trust Eye Hospital | Kariminejad A.,Kariminejad Najmabadi Pathology and Genetics Center | Ebadi F.,Diana Genetic Counseling Center | And 2 more authors.
Molecular Vision | Year: 2011

Purpose: To further explore the spectrum of mutations in the Visual System Homeobox 2 (VSX2/CHX10) gene previously found to be associated with autosomal recessive microphthalmia. Methods: We screened 95 probands with syndromic or isolated developmental ocular conditions (including 55 with anophthalmia/microphthalmia) for mutations in VSX2. Results: Homozygous mutations in VSX2 were identified in two out of five consanguineous families with isolated microphthalmia. A novel missense mutation, c.668G>C (p.G223A), was identified in a large Pakistani family with multiple sibships affected with bilateral microphthalmia. This p.G223A mutation affects the conserved CVC motif that was shown to be important for DNA binding and repression activities of VSX2. The second mutation, c.249delG (p.Leu84SerfsX57), was identified in an Iranian family with microphthalmia; this mutation has been previously reported and is predicted to generate a severely truncated mutant protein completely lacking the VSX2 homeodomain, CVC domain and COOHterminal regions. Conclusions: Mutations in VSX2 represent an important cause of autosomal recessive microphthalmia in consanguineous pedigrees. Identification of a second missense mutation in the CVC motif emphasizes the importance of this region for normal VSX2 function. © 2011 Molecular Vision.

Kariminejad A.,Kariminejad Najmabadi Pathology and Genetics Center
Journal of child neurology | Year: 2013

This report describes a case of megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome in a 1-year-old boy, born to healthy nonconsanguineous parents. Megalencephaly and bilateral postaxial polydactyly of upper and lower limbs were noted at birth. He had profound developmental delay and moderate hypotonia. Magnetic resonance imaging (MRI) of the brain revealed hydrocephalus, polymicrogyria in both frontal lobes and perisylvian regions, and thin corpus callosum. Array-comparative genomic hybridization was normal. The patient's clinical and radiologic findings fit the classic description of megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome. The possible overlap between megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome and other similar conditions is discussed.

Van Dijk F.S.,University Medical Center | Van Dijk F.S.,VU University Amsterdam | Cobben J.M.,Emma Childrens Hospital | Kariminejad A.,Kariminejad Najmabadi Pathology and Genetics Center | And 4 more authors.
Molecular Syndromology | Year: 2011

Osteogenesis imperfecta (OI) is characterized by susceptibility to bone fractures, with a severity ranging from subtle increase in fracture frequency to prenatal fractures. The first scientific description of OI dates from 1788. Since then, important milestones in OI research and treatment have, among others, been the classification of OI into 4 types (the 'Sillence classification'), the discovery of defects in collagen type I biosynthesis as a cause of most cases of OI and the use of bisphosphonate therapy. Furthermore, in the past 5 years, it has become clear that OI comprises a group of heterogeneous disorders, with an estimated 90% of cases due to a causative variant in the COL1A1 or COL1A2 genes and with the remaining 10% due to causative recessive variants in the 8 genes known so far, or in other currently unknown genes. This review aims to highlight the current knowledge around the history, epidemiology, pathogenesis, clinical/radiological features, management, and future prospects of OI. The text will be illustrated with clinical descriptions, including radiographs and, where possible, photographs of patients with OI. Copyright © 2011 S. Karger AG, Basel.

Sansbury F.H.,University of Exeter | Flanagan S.E.,University of Exeter | Houghton J.A.L.,University of Exeter | Shuixian Shen F.L.,Fudan University | And 6 more authors.
Diabetologia | Year: 2012

Aims: The gene SLC2A2 encodes GLUT2, which is found predominantly in pancreas, liver, kidney and intestine. In mice, GLUT2 is the major glucose transporter into pancreatic beta cells, and biallelic Slc2a2 inactivation causes lethal neonatal diabetes. The role of GLUT2 in human beta cells is controversial, and biallelic SLC2A2 mutations cause Fanconi-Bickel syndrome (FBS), with diabetes rarely reported. We investigated the potential role of GLUT2 in the neonatal period by testing whether SLC2A2 mutations can present with neonatal diabetes before the clinical features of FBS appear. Methods: We studied SLC2A2 in patients with transient neonatal diabetes mellitus (TNDM; n = 25) or permanent neonatal diabetes mellitus (PNDM; n = 79) in whom we had excluded the common genetic causes of neonatal diabetes, using a combined approach of sequencing and homozygosity mapping. Results: Of 104 patients, five (5%) were found to have homozygous SLC2A2 mutations, including four novel mutations (S203R, M376R, c.963+1G>A, F114LfsX16). Four out of five patients with SLC2A2 mutations presented with isolated diabetes and later developed features of FBS. Four out of five patients had TNDM (16% of our TNDM cohort of unknown aetiology). One patient with PNDM remains on insulin at 28 months. Conclusions: SLC2A2 mutations are an autosomal recessive cause of neonatal diabetes that should be considered in consanguineous families or those with TNDM, after excluding common causes, even in the absence of features of FBS. The finding that patients with homozygous SLC2A2 mutations can have neonatal diabetes supports a role for GLUT2 in the human beta cell. © 2012 Springer-Verlag.

Deml B.,Medical College of Wisconsin | Kariminejad A.,Kariminejad Najmabadi Pathology and Genetics Center | Borujerdi R.H.R.,Qom Welfare Organization | Muheisen S.,Medical College of Wisconsin | And 2 more authors.
PLoS Genetics | Year: 2015

Ocular coloboma results from abnormal embryonic development and is often associated with additional ocular and systemic features. Coloboma is a highly heterogeneous disorder with many cases remaining unexplained. Whole exome sequencing from two cousins affected with dominant coloboma with microcornea, cataracts, and skeletal dysplasia identified a novel heterozygous allele in MAB21L2, c.151 C>G, p.(Arg51Gly); the mutation was present in all five family members with the disease and appeared de novo in the first affected generation of the three-generational pedigree. MAB21L2 encodes a protein similar to C. elegans mab-21 cell fate-determining factor; the molecular function of MAB21L2 is largely unknown. To further evaluate the role of MAB21L2, zebrafish mutants carrying a p.(Gln48Serfs*5) frameshift truncation (mab21l2Q48Sfs*5) and a p.(Arg51_Phe52del) in-frame deletion (mab21l2R51_F52del) were developed with TALEN technology. Homozygous zebrafish embryos from both lines developed variable lens and coloboma phenotypes: mab21l2Q48Sfs*5 embryos demonstrated severe lens and retinal defects with complete lethality while mab21l2R51_F52del mutants displayed a milder lens phenotype and severe coloboma with a small number of fish surviving to adulthood. Protein studies showed decreased stability for the human p.(Arg51Gly) and zebrafish p.(Arg51_Phe52del) mutant proteins and predicted a complete loss-of-function for the zebrafish p.(Gln48Serfs*5) frameshift truncation. Additionally, in contrast to wild-type human MAB21L2 transcript, mutant p.(Arg51Gly) mRNA failed to efficiently rescue the ocular phenotype when injected into mab21l2Q48Sfs*5 embryos, suggesting this allele is functionally deficient. Histology, immunohistochemistry, and in situ hybridization experiments identified retinal invagination defects, an increase in cell death, abnormal proliferation patterns, and altered expression of several ocular markers in the mab21l2 mutants. These findings support the identification of MAB21L2 as a novel factor involved in human coloboma and highlight the power of genome editing manipulation in model organisms for analysis of the effects of whole exome variation in humans. © 2015 Deml et al.

Discover hidden collaborations