Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myoclonus-dystonia (M-D, DYT11) is a dystonia plus syndrome characterized by brief myoclonic jerks predominantly of neck and upper limbs in combination with focal or segmental dystonia. It is caused by heterozygous mutations of the epsilon-sarcoglycan (SGCE) gene on chromosome 7q21.3. We present three patients with heterozygous large deletions in the 7q21.13-21.3 region. By quantitative analysis of single nucleotide polymorphism (SNP) oligonucleotide arrays, the deletion size was determined to range from 1.63 to 8.78 Mb. All deletions contained the maternally imprinted SGCE gene and up to 43 additional neighbouring genes. Two of the patients presented with typical M-D, whereas one paediatric patient with split-hand/split-foot malformation and sensorineural hearing loss (SHFM1D, OMIM 220600) had not developed M-D at the age of 9 years. This patient had the largest deletion of 8.78 Mb (7q21.13-21.3) containing also SHFM1, DLX6 and DLX5, which had been previously shown to be deleted in SHFM1D. In two patients, the deletions removed the paternal allele of the KRIT1 gene, which is a major cause of cavernous cerebral malformations type 1 (CCM1). Only the adult patient showed asymptomatic cavernous cerebral malformations on cranial MRI, underlining age-dependent penetrance and haploinsufficiency as pivotal features of patients with KRIT1 mutations. All three deletions contained the COL1A2 gene. In contrast to dominant negative point mutations, which cause osteogenesis imperfecta with bone fractures, haploinsufficiency of COL1A2 resulted only in subtle symptoms like recurrent joint subluxation or hypodontia. Assessing copy number variations by SNP arrays is an easy and reliable technique to delineate the size of human interstitial deletions. It will therefore become a standard technique to study patients, in whom heterozygous whole gene deletions are detected and information on neighbouring deleted genes is required for comprehensive genetic counselling and clinical management.
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PMID:Genomic deletion size at the epsilon-sarcoglycan locus determines the clinical phenotype. 1789 12

Myoclonus-dystonia (M-D) is an autosomal-dominant movement disorder caused by mutations in SGCE. We investigated the frequency and type of SGCE mutations with emphasis on gene dosage alterations and explored the associated phenotypes. We tested 35 M-D index patients by multiplex ligation-dependent probe amplification (MLPA) and genomic sequencing. Mutations were found in 26% (9/35) of the cases, all but three with definite M-D. Two heterozygous deletions of the entire SGCE gene and flanking DNA and a heterozygous deletion of exon 2 only were detected, accounting for 33% (3/9) of the mutations found. Both large deletions contained COL1A2 and were additionally associated with joint problems. Further, we discovered one novel small deletion (c.771_772delAT, p.C258X) and four recurrent point mutations (c.289C>T, p.R97X; c.304C>T, p.R102X; c.709C>T, p.R237X; c.1114C>T, p.R372X). A Medline search identified 22 articles on SGCE mutational screening. Sixty-four unrelated M-D patients were described with 41 different mutations. No genotype-phenotype association was found, except in patients with deletions encompassing additional genes. In conclusion, a rigorous clinical preselection of patients and careful accounting for non-motor signs should precede mutational tests. Gene dosage studies should be included in routine SGCE genetic testing.
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PMID:Myoclonus-dystonia: significance of large SGCE deletions. 1820 93

We report on a boy with myoclonus-dystonia (M-D), language delay, and malformative anomalies. Genetic investigations allowed the identification of an apparently balanced de novo reciprocal translocation, t(7;9)(q21;p23). Breakpoint-region mapping using fluorescent in situ hybridization (FISH) analysis of bacterial artificial chromosome (BAC) clone probes identified microdeletions of 3.7 and 5.2 Mb within 7q21 and 9p23 breakpoint regions, respectively. Genotyping with microsatellite markers showed that deletions originated from paternal alleles. The deleted region on chromosome 7q21 includes a large imprinted gene cluster. SGCE and PEG10 are two maternally imprinted genes. SGCE mutations are implicated in M-D. In our case, M-D is due to deletion of the paternal allele of the SGCE gene. PEG10 is strongly expressed in the placenta and is essential for embryo development. Prenatal growth retardation identified in the patient may be due to deletion of the paternal allele of the PEG10 gene. Other genes in the deleted region on chromosome 7 are not imprinted. Nevertheless, a phenotype can be due to haploinsufficiency of these genes. KRIT1 is implicated in familial forms of cerebral cavernous malformations, and COL1A2 may be implicated in very mild forms of osteogenesis imperfecta. The deleted region on chromosome 9 overlaps with the candidate region for monosomy 9p syndrome. The proband shows dysmorphic features compatible with monosomy 9p syndrome, without mental impairment. These results emphasize that the phenotypic abnormalities of apparently balanced de novo translocations can be due to cryptic deletions and that the precise mapping of these aneusomies may improve clinical management.
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PMID:Cryptic 7q21 and 9p23 deletions in a patient with apparently balanced de novo reciprocal translocation t(7;9)(q21;p23) associated with a dystonia-plus syndrome: paternal deletion of the epsilon-sarcoglycan (SGCE) gene. 1865 Oct 96