Browsing by Subject "Quadrupedal locomotion"
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Item Open Access Identification of ATP8A2 gene mutation in a consaguineous family segregating cerebellar atrophy and quadrupedal gait(Bilkent University, 2012) Onat, Onur EmreCerebellar ataxia, mental retardation, and dysequilibrium syndrome is a rare and heterogeneous neurodevelopmental disorder characterized by cerebellar atrophy, dysarthric speech, and quadrupedal locomotion. Here, a consanguineous family with four affected individuals which suggest an autosomal recessive inheritance was investigated. Homozygosity mapping analysis using high-resolution genotyping arrays in two affected individuals revealed four shared homozygous regions on 13q12, 19p13.3, 19q13.2, and 20q12. Target enrichment and next-generation sequencing of these regions in an affected individual was uncovered 11 novel protein altering variants which were filtered against dbSNP132 and 1000 genomes databases. Further population filtering using personal genome databases and previous exome sequencing datasets, segregation analysis, geographically-matched population screening, and prediction approaches revealed a novel missense mutation, p.I376M, in ATP8A2 segregated with the phenotype in the family. The mutation resides in a highly conserved C-terminal transmembrane region of E1-E2 ATPase domain. ATP8A2 is mainly expressed in brain, in particular with the highest levels at cerebellum which is a crucial organ for motor coordination. Mice deficient with Atp8a2 revealed impaired axonal transport in the motor neurons associated with severe cerebellar ataxia and body tremors. Recently, an unrelated individual with a de novo t(10;13) balanced translocation whose one of the ATP8A2 allele was disrupted has been identified. This patient shares similar neurological phenotypes including severe mental retardation and hypotonia. These findings suggest a role for ATP8A2 in the neurodevelopment, especially in the development of cerebro-cerebellar structures required for posture and gait in humans.Item Open Access Missense mutation in the ATPase, aminophospholipid transporter protein ATP8A2 is associated with cerebellar atrophy and quadrupedal locomotion(Nature Publishing Group, 2013) Onat, O. E.; Gulsuner, S.; Bilguvar, K.; Basak, A. N.; Topaloglu, H.; Tan, M.; Tan, U.; Gunel, M.; Ozcelik, T.Cerebellar ataxia, mental retardation and dysequilibrium syndrome is a rare and heterogeneous condition. We investigated a consanguineous family from Turkey with four affected individuals exhibiting the condition. Homozygosity mapping revealed that several shared homozygous regions, including chromosome 13q12. Targeted next-generation sequencing of an affected individual followed by segregation analysis, population screening and prediction approaches revealed a novel missense variant, p.I376M, in ATP8A2. The mutation lies in a highly conserved C-terminal transmembrane region of E1 E2 ATPase domain. The ATP8A2 gene is mainly expressed in brain and development, in particular cerebellum. Interestingly, an unrelated individual has been identified, in whom mental retardation and severe hypotonia is associated with a de novo t(10;13) balanced translocation resulting with the disruption of ATP8A2. These findings suggest that ATP8A2 is involved in the development of the cerebro-cerebellar structures required for posture and gait in humans. © 2013 Macmillan Publishers Limited All rights reserved.Item Open Access Neuro-ophthalmologic findings in humans with quadrupedal locomotion(2012) Sarac O.; Gulsuner, S.; Yildiz-Tasci, Y.; Ozcelik, T.; Kansu, T.Purpose: To report the neuro-ophthalmologic findings in four patients from the same family with cerebellar ataxia, mental retardation, and dysequilibrium syndrome (CAMRQ)2 associated with quadrupedal locomotion. Method: A case series. Results: All four patients carry the private missense mutation, WDR81 p.P856L. The brain Magnetic Resonance Imaging (MRI) of these patients revealed morphological abnormalities including mild hypoplasia of the corpus callosum, and atrophy of superior, middle, and inferior peduncles of the cerebellum. All patients had down-beat nystagmus, while two male patients additionally had bilateral temporal disc pallor along with ring-shaped macular atrophy. Conclusions: The neuro-ophthalmic examination in CAMRQ2 revealed downbeat nystagmus in all patients, and temporal disc pallor and macular atrophy in two patients. It remains to be determined whether these findings are consistent in other forms of CAMRQ with mutations in VLDLR or CA8. © 2012 Informa Healthcare USA, Inc.Item Open Access Quadrupedal gait in humans : identification and partial characterization of a novel gene WD repeat domain 81 (WDR81)(Bilkent University, 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.