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Mutations in the emery-dreifuss muscular dystrophy gene and evidence for an autosomal form
S15 CIS4
CIS5
MOLECULAR INVESTIGATION OF BETHLEM MYOPATHY
DISTAL MYOPATHIES AND OVERLAPPING FORMS AND INTRAFAMILIAR VARIABILITY BETWEEN DISTAL MYOPATHIES AND LIMBGIRDLE MUSCULAR DYSTROPHIES.
Pieter A Bolhuis, Academic Medical Center Amsterdam, Netherlands Genome-wide investigation of genetic linkage in Bethlem families localized the disease gene at the telomeric long arm of chromosome 21. Two-point lod score with marker PFKL was > 6 at 0 0.01. The localization was confirmed in several other families except one. Since the telomeric region of chromosome 21q contains the genes collagen (COL) VIAl and COL VIA2, this family was investigated for linkage to chromosome 2q in the region containing the COL V1A3 gene. Strong linkage was found, suggesting that Bethlem myopathy is a collagen disorder. Collagen type V1 is a non-fibriUous collagen containing large globular domains. The protein has adhesive properties and is thought to be important to the organization of the extracellular matrix. Expression during development is stage and tissue specific. Transcription of COL VIA1 is increased during myoblast differentiation. COL VIA1 and VIA2 cDNA from patients is analyzed for the presence of mutations.
CIS6
MUTATIONS IN THE EMERY-DREIFUSS M U S C U L A R D Y S T R O P H Y GENE A N D EVIDENCE FOR AN AUTOSOMAL FORM Silvia Bione, John R.W. Yates, Steve T. Warren, Lueiano Medini, ~ Morandi and Danlela Tonlolo Istituto di G-enefica Biochimiea ed Evoluzionistiea, CNR Pavia; Department of Pathology, Cambridge University, Cambridge UK; Department of Biochemistry and Pediatrics, Emory University School of Medecine, Atlanta, USA; Istituto Ortopedico Rizzoli, Bologna; Istituto Neurologieo Besta, Milano. The gene for EDMD was identified among a large number of possible candidates in the telomerie region of Xq28. The EDMD gene is only 2 kb long and encodes a protein of 254 aa, called emerin. The function of the emerin protein is still unknown. Until now we have studied 16 familial and 13 sporadic cases; in 15 of 16 familial patients we have identified different mutations that in all instance would produce the complete lack or a u'uncated form of the protein. The most distally truncated forms lack the hydrophilic C-terminal domain which should serve as a membrane anchor of the protein. In one family we failed to identify mutations in the EDMD gene despite a clinical diagnosis of typical EDMD. In this family however the carrier female was also affected. It is likely that this is the autosomal dominant form of the disease.
somer H, Udd B, Nokelainen P, Makel~-Bengn Peltonen L. Dept. of Neurology University Helsinki, Vasa Central Hospital, and Dept. Molecular Genetics National Institute Public Health Helsinki, Finland.
P, of of of
In 1991 we described a large consanguineous family with two separate clinical phenotypes: a limb-girdle type dystrophy in 7 and a late onset distal myopathy of lower legs (TMD) in 16 patients. We now have diagnosed TMD nationwide in 130 patients. None of them come from consanguineous families and the proximal form is not seen in their relatives. This phenotypic dualism could be due to extreme variation within one disease or coexistence of two separate diseases. One explanation offered also in Welander's disease is the proximal myopathy patients being homozygous for the distal myopathy inherited in AD fashion. None of the established muscular dystrophy loci shows a linkage to either of the phenotypes. The exclusion percentage varies from 19 to 40 percent in multipoint analysis, depending on the inheritance model applied.
CIS7
SSCP analysis of the emerin gene Luisa Politano 1 and Vincenzo Nigro2. 1Servizio di Cardiomiologia Dipartimento di Internistica Cliniea e Sperimentale and 2lstituto ~li Patologia. Generale. Universit~ degli Studi di Napoli 80138 Napoli ITALY Emery-Dreifuss muscular dystrophy (EMD; Mc Kusick N* 310300) is a rare X-linked recessive disorder, characterized by slowly progressive muscle wasting, early joint contractures and frequent cardiac involvement. Conduction defect is present as an atrioventricular block with a risk of sudden death. Patients often require ventricular pacing. ENID has a lower incidence and milder course than the other X-linked MD, Duchenne muscular dystrophy. Gene was l~eviously localized at Xq28. Bione et al. (Nature Genet. 8, 323-327, 1994) identified 5 null mutations in a eDNA coding for a serin-rich protein of 254 amino acid, that they called emerin. Ciceodicola et al. have established the entire physical map and sequence of the Xq28 region where the emerin gene was localized. Based on this genomic sequence, we designed 7 PCR primer pairs to amplify the entire emerin coding sequence together with the exonintron junctions to detect point mutations by the single strand conformation polymoiphism (SSCP) approach. In two families we identified novel mutations. In the first, we found an aberrant donor splice-site of intron 1 (G to T, +1 from 141). More interestingly, the second case (N203) was associated with a premature translation termination at Gin 228 (C 740 T), Considering that emerin is 254 amino acid long, the nonsense codon at position 228 represents the most distal mutation so far de~ribed. This fact defines the missing 27 last amino acids as necessary for emerin function. The region codes for residues involved in a putative transmembrane domain. This mutation is the most stgnifieative proof of an association between the preservation of the emerin hydrophobic domain and its function.
CIS5
MOLECULAR INVESTIGATION OF BETHLEM MYOPATHY
DISTAL MYOPATHIES AND OVERLAPPING FORMS AND INTRAFAMILIAR VARIABILITY BETWEEN DISTAL MYOPATHIES AND LIMBGIRDLE MUSCULAR DYSTROPHIES.
Pieter A Bolhuis, Academic Medical Center Amsterdam, Netherlands Genome-wide investigation of genetic linkage in Bethlem families localized the disease gene at the telomeric long arm of chromosome 21. Two-point lod score with marker PFKL was > 6 at 0 0.01. The localization was confirmed in several other families except one. Since the telomeric region of chromosome 21q contains the genes collagen (COL) VIAl and COL VIA2, this family was investigated for linkage to chromosome 2q in the region containing the COL V1A3 gene. Strong linkage was found, suggesting that Bethlem myopathy is a collagen disorder. Collagen type V1 is a non-fibriUous collagen containing large globular domains. The protein has adhesive properties and is thought to be important to the organization of the extracellular matrix. Expression during development is stage and tissue specific. Transcription of COL VIA1 is increased during myoblast differentiation. COL VIA1 and VIA2 cDNA from patients is analyzed for the presence of mutations.
CIS6
MUTATIONS IN THE EMERY-DREIFUSS M U S C U L A R D Y S T R O P H Y GENE A N D EVIDENCE FOR AN AUTOSOMAL FORM Silvia Bione, John R.W. Yates, Steve T. Warren, Lueiano Medini, ~ Morandi and Danlela Tonlolo Istituto di G-enefica Biochimiea ed Evoluzionistiea, CNR Pavia; Department of Pathology, Cambridge University, Cambridge UK; Department of Biochemistry and Pediatrics, Emory University School of Medecine, Atlanta, USA; Istituto Ortopedico Rizzoli, Bologna; Istituto Neurologieo Besta, Milano. The gene for EDMD was identified among a large number of possible candidates in the telomerie region of Xq28. The EDMD gene is only 2 kb long and encodes a protein of 254 aa, called emerin. The function of the emerin protein is still unknown. Until now we have studied 16 familial and 13 sporadic cases; in 15 of 16 familial patients we have identified different mutations that in all instance would produce the complete lack or a u'uncated form of the protein. The most distally truncated forms lack the hydrophilic C-terminal domain which should serve as a membrane anchor of the protein. In one family we failed to identify mutations in the EDMD gene despite a clinical diagnosis of typical EDMD. In this family however the carrier female was also affected. It is likely that this is the autosomal dominant form of the disease.
somer H, Udd B, Nokelainen P, Makel~-Bengn Peltonen L. Dept. of Neurology University Helsinki, Vasa Central Hospital, and Dept. Molecular Genetics National Institute Public Health Helsinki, Finland.
P, of of of
In 1991 we described a large consanguineous family with two separate clinical phenotypes: a limb-girdle type dystrophy in 7 and a late onset distal myopathy of lower legs (TMD) in 16 patients. We now have diagnosed TMD nationwide in 130 patients. None of them come from consanguineous families and the proximal form is not seen in their relatives. This phenotypic dualism could be due to extreme variation within one disease or coexistence of two separate diseases. One explanation offered also in Welander's disease is the proximal myopathy patients being homozygous for the distal myopathy inherited in AD fashion. None of the established muscular dystrophy loci shows a linkage to either of the phenotypes. The exclusion percentage varies from 19 to 40 percent in multipoint analysis, depending on the inheritance model applied.
CIS7
SSCP analysis of the emerin gene Luisa Politano 1 and Vincenzo Nigro2. 1Servizio di Cardiomiologia Dipartimento di Internistica Cliniea e Sperimentale and 2lstituto ~li Patologia. Generale. Universit~ degli Studi di Napoli 80138 Napoli ITALY Emery-Dreifuss muscular dystrophy (EMD; Mc Kusick N* 310300) is a rare X-linked recessive disorder, characterized by slowly progressive muscle wasting, early joint contractures and frequent cardiac involvement. Conduction defect is present as an atrioventricular block with a risk of sudden death. Patients often require ventricular pacing. ENID has a lower incidence and milder course than the other X-linked MD, Duchenne muscular dystrophy. Gene was l~eviously localized at Xq28. Bione et al. (Nature Genet. 8, 323-327, 1994) identified 5 null mutations in a eDNA coding for a serin-rich protein of 254 amino acid, that they called emerin. Ciceodicola et al. have established the entire physical map and sequence of the Xq28 region where the emerin gene was localized. Based on this genomic sequence, we designed 7 PCR primer pairs to amplify the entire emerin coding sequence together with the exonintron junctions to detect point mutations by the single strand conformation polymoiphism (SSCP) approach. In two families we identified novel mutations. In the first, we found an aberrant donor splice-site of intron 1 (G to T, +1 from 141). More interestingly, the second case (N203) was associated with a premature translation termination at Gin 228 (C 740 T), Considering that emerin is 254 amino acid long, the nonsense codon at position 228 represents the most distal mutation so far de~ribed. This fact defines the missing 27 last amino acids as necessary for emerin function. The region codes for residues involved in a putative transmembrane domain. This mutation is the most stgnifieative proof of an association between the preservation of the emerin hydrophobic domain and its function.