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Neuromuscul Disord. 2017 Dec;27(12):1106-1114. doi: 10.1016/j.nmd.2017.09.004. Epub 2017 Sep 21.

Origin of the myotonic dystrophy type 1 mutation in Mexican population and influence of Amerindian ancestry on CTG repeat allelic distribution.

Author information

1
Laboratory of Genomic Medicine, Department of Genetics, National Rehabilitation Institute (INR), Mexico City, Mexico; Biomedical Sciences Program, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Mexico City, Mexico.
2
Laboratory of Genomic Medicine, Department of Genetics, National Rehabilitation Institute (INR), Mexico City, Mexico; Department of Genetics and Molecular Biology, Center of Research and Advanced Studies-National Polytechnic Institute (CINVESTAV-IPN), Mexico City, Mexico.
3
Department of Toxicology, CINVESTAV-IPN, Mexico City, Mexico.
4
Laboratory of Immunogenomics and Metabolic Diseases, National Genomic Medicine Institute (INMEGEN), Mexico City, Mexico.
5
Laboratory of Genomic Medicine, Department of Genetics, National Rehabilitation Institute (INR), Mexico City, Mexico.
6
Laboratory of Sinovial Liquid, INR, Mexico City, Mexico.
7
Laboratory of Diagnostic Molecular Biology (BIMODI), Querétaro, Qro, Mexico.
8
Department of Genetics and Molecular Biology, Center of Research and Advanced Studies-National Polytechnic Institute (CINVESTAV-IPN), Mexico City, Mexico. Electronic address: bcisnero@cinvestav.mx.
9
Laboratory of Genomic Medicine, Department of Genetics, National Rehabilitation Institute (INR), Mexico City, Mexico; Biomedical Sciences Program, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Mexico City, Mexico. Electronic address: maganasm@hotmail.com.

Abstract

Myotonic dystrophy type 1 is caused by expansion of a CTG trinucleotide repeat situated in the DMPK gene. Worldwide genetic studies suggest a single or limited number of mutational events cause the disease. However, distribution of CTG alleles and disease incidence varies among ethnicities. Due to the great ethnic diversity of the Mexican population, the present study was aimed at analyzing the impact of different lineages in shaping the CTG-repeat allelic distribution in the contemporary Mexican-Mestizo population as well as to shed light on the DM1 ancestral origin. Distribution of CTG-repeat alleles was similar among Mestizo and Amerindian subpopulations with (CTG)11-13 being the most frequent alleles in both groups, which implies that Mexican-Mestizo allelic distribution has been modeled by Amerindian ancestry. We diagnosed a relatively high number of cases, consistent with the high frequency of large-normal alleles found in Mexican subpopulations. Haplotype analysis using various polymorphic-markers in proximity to DMPK gene indicates that a single founder mutation originates myotonic dystrophy type 1 in Mexico; however, Y-STR haplogroups data and the presence of pre-mutated and large normal alleles in Amerindians support the hypothesis that both European and Amerindian ancestral chromosomes might have introduced the disease to the Mexican population, which was further disseminated through mestizaje.

KEYWORDS:

Amerindian population; CTG repeats; Haplotype; Mexican mestizo population; Myotonic dystrophy type 1; Polymorphism

PMID:
29054426
DOI:
10.1016/j.nmd.2017.09.004
[Indexed for MEDLINE]

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