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. 2019 Apr;18(2):188-194.
doi: 10.1007/s12311-018-0977-7.

Selective Forces Related to Spinocerebellar Ataxia Type 2

Lucas Schenatto Sena  1 , Raphael Machado Castilhos  2 , Eduardo Preusser Mattos  1   3 , Gabriel Vasata Furtado  1   3 , José Luiz Pedroso  4 , Orlando Barsottini  4 , Maria Marla Paiva de Amorim  5 , Clecio Godeiro  5 , Maria Luiza Saraiva Pereira  1   6   7   3 , Laura Bannach Jardim  8   9   10   11
Affiliations

Selective Forces Related to Spinocerebellar Ataxia Type 2

Lucas Schenatto Sena et al. Cerebellum. 2019 Apr.

Erratum in

Abstract

Spinocerebellar ataxia type 2 (SCA2) is caused by an unstable expanded CAG repeat tract (CAGexp) at ATXN2. Although prone to selective forces such as anticipation, SCA2 frequency seems to be stable in populations. Our aim was to estimate reproductive success, segregation patterns, and role of anticipation in SCA2. Adult subjects from families with molecular diagnosis provided data about all his/her relatives. Affected and unaffected sibs older than 65.7 years of age were used to estimate reproductive success and segregation patterns. Twenty-one SCA2 families were studied, including 1017 individuals (164 affected) who were born from 1840 to 2012. The median number of children of the non-carriers and carriers, among 99 subjects included in the reproductive success analysis, were 2 and 3 (p < 0.025), respectively. Therefore, the reproductive success of carriers was 1.5. There were 137 non-carriers (59.6%) and 93 carriers (40.4%) (p = 0.04), among subjects included in the segregation analysis. Age at onset across generations pointed to anticipation as a frequent phenomenon. We raised evidence in favor of increased reproductive success related to the carrier state at ATXN2, and segregation distortion favoring normal alleles. Since majority of normal alleles analyzed carried 22 repeats, we propose that this distortion segregation can be related to the high frequency of this allele in human chromosomes.

Keywords: Anticipation; CAG repeats; Reproductive success; SCA2; Segregation distortion; Spinocerebellar ataxia type 2.

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References

    1. Pulst SM. Spinocerebellar ataxia type 2. GeneReviews® [Internet].2015. https://www.ncbi.nlm.nih.gov/books/NBK1275/
    1. Laffita-Mesa JM, Velázquez-Pérez LC, Santos Falcón N, et al. Unexpanded and intermediate CAG polymorphisms at the SCA2 locus (ATXN2) in the Cuban population: evidence about the origin of expanded SCA2 alleles. European Journal of Human Genetics. 2012;20(1):41–9. https://doi.org/10.1038/ejhg.2011.15 . - DOI - PubMed
    1. Montcel S.T, Durr A, Bauer P, et al. Modulation of the age at onset in spinocerebellar ataxia by CAG tracts in various genes. Brain 2014. Pages 2444–2455.
    1. Geschwind DH, Perlman S, Figueroa CP, Treiman LJ, Pulst SM. The prevalence and wide clinical spectrum of the spinocerebellar ataxia type 2 trinucleotide repeat in patients with autosomal dominant cerebellar ataxia. Am J Hum Genet. 1997;60(4):842–50. - PubMed - PMC
    1. Matilla-Dueñas A, Sánchez I, Corral-Juan M, Dávalos A, Alvarez R, Latorre P. Cellular and molecular pathways triggering neurodegeneration in the spinocerebellar ataxias. Cerebellum. 2010 Jun;9(2):148–66. - DOI - PubMed

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