Browsing by Subject "Unertan syndrome"
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Item Open Access Mutations in the very low-density lipoprotein receptor VLDLR cause cerebellar hypoplasia and quadrupedal locomotion in humans(National Academy of Sciences, 2008) Ozcelik, T.; Akarsu, N.; Uz, E.; Caglayan, S.; Gulsuner, S.; Onat, O. E.; Tan, M.; Tan, U.Quadrupedal gait in humans, also known as Unertan syndrome, is a rare phenotype associated with dysarthric speech, mental retardation, and varying degrees of cerebrocerebellar hypoplasia. Four large consanguineous kindreds from Turkey manifest this phenotype. In two families (A and D), shared homozygosity among affected relatives mapped the trait to a 1.3-Mb region of chromosome 9p24. This genomic region includes the VLDLR gene, which encodes the very low-density lipoprotein receptor, a component of the reelin signaling pathway involved in neuroblast migration in the cerebral cortex and cerebellum. Sequence analysis of VLDLR revealed nonsense mutation R257X in family A and single-nucleotide deletion c2339delT in family D. Both these mutations are predicted to lead to truncated proteins lacking transmembrane and signaling domains. In two other families (B and C), the phenotype is not linked to chromosome 9p. Our data indicate that mutations in VLDLR impair cerebrocerebellar function, conferring in these families a dramatic influence on gait, and that hereditary disorders associated with quadrupedal gait in humans are genetically heterogeneous.Item Open Access Quadrupedal gait in humans : identification and partial characterization of a novel gene WD repeat domain 81 (WDR81)(2011) Gülsüner, Süleyman İsmailIdenti cation of disease genes responsible for cerebellar phenotypes provides mechanistic insights into the development of cerebellum. Neural pathways involved in bipedal gait in humans is not completely understood. Cerebellar ataxia, mental retardation, and disequilibrium syndrome (CAMRQ) is a rare neurodevelopmental disorder accompanied by quadrupedal gait, dysarthric speech and cerebellar hypoplasia. A large consanguineous family exhibiting this rare disorder was investigated in this study. Disease locus was mapped to a 7.1 Mb region on chromosome 17p by genetic analysis. Targeted capture and massively parallel DNA sequencing using the DNA of three a ected and two carrier individuals enabled the identi cation of a novel variant, p.P856L, in a predicted transcript of WD repeat domain 81 gene (WDR81). Several exclusion lters including segregation analysis, identi cation of rare polymorphisms, extended pedigree screen and bioinformatics evaluation was performed. Expression analysis revealed highest levels of transcripts in cerebellum and corpus callosum. In mouse brain Wdr81 RNA was observed in cerebellum, especially in Purkinje cell layer. The major structural abnormalities of the patients were atrophy of superior, middle and inferior cerebellar peduncles and corpus callosum. These ndings are compatible with the expression pattern of the gene. Analysis of the developing mouse brain revealed that, the expression pattern of the gene was correlated with those involved in neuronal di erentiation. This study was one of the rst examples of the utility of next generation sequencing in discovery of genes associated with Mendelian phenotypes.