Anticipation (genetics)

About: Anticipation (genetics) is a research topic. Over the lifetime, 669 publications have been published within this topic receiving 21784 citations. The topic is also known as: Genetic Anticipation & Anticipation, Genetic.

Anticipation of age at onset in multiple sclerosis: methodologic pitfalls.

Abstract: Background/aim - There are several reports that claim anticipation in complex or polygenic diseases such as multiple sclerosis (MS), Crohn disease or schizophrenia. The aim of the present study was to assess age at onset of MS during the last 60 years in the region of Costa de Ponent (Barcelona, Spain) showing how apparent changes in age at onset between generations can be an artefact of analysis based on cohorts that have not been followed enough time. Methods - The study comprised 1100 patients diagnosed of MS. The method used to correct for follow-up time bias involves constructing comparison cohorts that had been observed for the same amount of time. To ensure equal follow-up times, we restricted our analysis to patients whose onset was by 37 years of age (percentile 75) and were at least 37 years old. We analysed differences in age at onset using log-rank test to compare survival curves estimated by Kaplan-Meier method. Results - Age at onset decreases progressively from older to younger generations. However, when adjustment to equal follow-up time was done, anticipation in age at onset was not found. Conclusion - Anticipation of age at onset is undetectable when adjusted for follow-up time.

The influence of parental age and gender on anticipation in familial B-cell malignancies.

Abstract: Anticipation occurs when a disease manifests at an earlier age and/or with an increased clinical severity in the next generation. Its relationship with parental age and gender is relevant to the patterns of genetic transmission of familial B-cell neoplasms. One hundred and sixty pairs [44 non-Hodgkin’s lymphoma (NHL), 38 Hodgkin’s disease (HD), 48 HD/NHL, and 30 CLL] were analyzed retrospectively for presence of anticipation in paternal (PT), maternal (MT), and overall transmission. Overall mean anticipation measured −23.0 yr, and varied between −18.93 and −26.46 yr with no significant difference among different diseases, except between CLL and mixed HD/NHL (mean difference −7.68 yr, p=0.03). A significant Pearson correlation (PC) between the parental age at conception and anticipation was found for all malignancies (PC=−0.339, p<0.0001), with the exception of mixed HD/NHL pairs of MT. Higher PCs were observed with PT than MT for all diseases. Anticipation manifests in all familial B-cell malignancies analyzed and it correlates with the parental age at conception. Although less prominent than with neurological disease, this phenomenon indicates a possible germline inheritance of B-cell malignancies and a common genetic basis for HD and NHL.

Phenotype variability and early onset ataxia symptoms in spinocerebellar ataxia type 7: comparison and correlation with other spinocerebellar ataxias

Abstract: The spinocerebellar ataxias (SCA) are a group of neurodegenerative disorders characterized by heterogeneous clinical presentation. Spinocerebellar ataxia type 7 (SCA7) is caused by an abnormal CAG repeat expansion and includes cerebellar signs associated with visual loss and ophthalmoplegia. Marked anticipation and dynamic mutation is observed in SCA7. Moreover, phenotype variability and very early onset of symptoms may occur. In this article, a large series of Brazilian patients with different SCA subtypes was evaluated, and we compared the age of onset of SCA7 with other SCA. From the 26 patients with SCA7, 4 manifested their symptoms before 10-year-old. Also, occasionally the parents may have the onset of symptoms after their children. In conclusion, our study highlights the genetic anticipation phenomenon that occurs in SCA7 families. Patients with very early onset ataxia in the context of a remarkable family history, must be considered and tested for SCA7.

A dominant spinocerebellar ataxia gene (SCA5) in a family descendent from the paternal grandparents of President Lincoln maps to chromosome 11

Abstract: Four different genes that cause spinocerebellar ataxia (SCA1, SCA2, Machado Joseph`s Disease (MJD)/SCA3 and SCA4) have been mapped to chromosomes 6p, 12q, 14q, and 16q, respectively. We have examined and collected 170 individuals (56 affected) from a previously unreported 10 generation kindred (the Lincoln Family) with a dominant ataxia that is clinically and genetically distinct from those previously mapped. The family has two major branches from Indiana and Kentucky. Of historical interest is that both branches descend from the paternal grandparents of President Abraham Lincoln. While the ataxia in this kindred is disabling, the most striking clinical distinction from SCA1, SCA2 and MJD/SCA3 is that it is generally not life threatening. This clinical difference is explained by the absence of bulbar paralysis and lower motor neuron degeneration that causes respiratory muscle weakness. We have mapped the gene, SCA5, using microsatellite markers spaced at 20-40 cM intervals throughout the genome. After 75 markers, the first to demonstrate a lod score greater than 3.0 was D11S871 (Zmax=5.05). Four additional markers from the centromeric region of chromosome 11 also gave lod scores greater than 3. The highest lod scores were 12.3 for both D11S905 ({theta}=0.056) and D11S913 ({theta}=0.030). Multipoint linkage and haplotype analysesmore » indicate the most likely location for SCA5 is within the 7 cM interval between GATA2A01 and D11S913. A statistical analysis of the age of onset of parent-offspring pairs within the family supports (p<0.0002) the presence of anticipation. Several dramatic examples of anticipation have been observed in which grandmothers have onsets 10-20 years later in life than their daughters who have onsets 10-20 years later than their children. Interestingly, all four of the juvenile onset cases are maternally inherited, suggesting a maternal bias in anticipation for SCA5 rather than a paternal bias as seen with SCA1.« less