Dataset Information

The frequency of SMN gene variants lacking exon 7 and 8 is highly population dependent.

ABSTRACT: Spinal Muscular Atrophy (SMA) is a disorder characterized by the degeneration of motor neurons in the spinal cord, leading to muscular atrophy. In the majority of cases, SMA is caused by the homozygous absence of the SMN1 gene. The disease severity of SMA is strongly influenced by the copy number of the closely related SMN2 gene. In addition, an SMN variant lacking exons 7 and 8 has been reported in 8% and 23% of healthy Swedish and Spanish individuals respectively. We tested 1255 samples from the 1000 Genomes Project using a new version of the multiplex ligation-dependent probe amplification (MLPA) P021 probemix that covers each SMN exon. The SMN variant lacking exons 7 and 8 was present in up to 20% of individuals in several Caucasian populations, while being almost completely absent in various Asian and African populations. This SMN1/2?7-8 variant appears to be derived from an ancient deletion event as the deletion size is identical in 99% of samples tested. The average total copy number of SMN1, SMN2 and the SMN1/2?7-8 variant combined was remarkably comparable in all populations tested, ranging from 3.64 in Asian to 3.75 in African samples.

SUBMITTER: Vijzelaar R

PROVIDER: S-EPMC6655720 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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The frequency of SMN gene variants lacking exon 7 and 8 is highly population dependent.

Vijzelaar Raymon R Snetselaar Reinier R Clausen Martijn M Mason Amanda G AG Rinsma Marrit M Zegers Marinka M Molleman Naomi N Boschloo Renske R Yilmaz Rizkat R Kuilboer Romy R Lens Sylvia S Sulchan Syamiroh S Schouten Jan J

PloS one 20190724 7

Spinal Muscular Atrophy (SMA) is a disorder characterized by the degeneration of motor neurons in the spinal cord, leading to muscular atrophy. In the majority of cases, SMA is caused by the homozygous absence of the SMN1 gene. The disease severity of SMA is strongly influenced by the copy number of the closely related SMN2 gene. In addition, an SMN variant lacking exons 7 and 8 has been reported in 8% and 23% of healthy Swedish and Spanish individuals respectively. We tested 1255 samples from t ...[more]

PMID: 31339938

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Project description:Hereditary HFE-linked hemochromatosis is a frequent recessive disorder among individuals of northern European ancestry. The clinical characteristic of this disease is the gradual accumulation of iron in internal organs, which ultimately may lead to organ damage and death. Three allelic variants of HFE gene have been correlated with hereditary hemochromatosis: C282Y is significantly associated with hereditary hemochromatosis in populations of Celtic origin, H63D and S65C are associated with milder form of iron overload. In this study we performed mutation analysis to identify allele frequency of the three variants of HFE gene in Jordanian Arab population, to assess deviations of these frequencies from those detected elsewhere, and to determine if there is an increased frequency of these variants in a diabetic population (Type 2 diabetes) from the same area. DNA was extracted from blood samples of 440 individuals attending King Abdullah University Hospital for ambulatory services. We used polymerase chain reaction (PCR) to amplify exons 2 and 4 of the HFE gene then restriction fragment length polymorphism (RFLP) method to detect the variants. There were neither homozygous nor heterozygous for C282Y variant. For the H63D variant, 0.68% were homozygous and 21.1% were heterozygous. For the S65C variant, there were no homozygous and 0.23% were heterozygous. Allelic frequencies were, 0%, 11.25%, and 0.11% for C282Y, H63D, and S65C, respectively. Our samples were subdivided into two categories of type 2 diabetic (89 cases) and controls (blood donors, 204 cases) and compared with regard to the H63D variant. Both groups did not have homozygous H63D variant. H63D heterozygous in diabetics were 23.60% and in blood donor controls 22.55%. Allelic frequency of the mutant H63D allele was 11.80% in diabetics and 11.27% for the blood donor controls. This is the first study to show the frequency of the three hemochromatosis gene variants in Jordan with the interesting finding of no C282Y allele detected in 440 samples. Additionally, no significant difference was observed in H63D variant frequency in type 2 diabetics as compared to controls.

Dataset Information

The frequency of SMN gene variants lacking exon 7 and 8 is highly population dependent.

Publications

The frequency of SMN gene variants lacking exon 7 and 8 is highly population dependent.

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