Topic
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.
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TL;DR: A family is presented in which the number of repeats apparently regressed from approximately 110 in the mother to 44 in her daughter, and the daughter is a carrier of the fragile X mutation based upon the segregation pattern of Xq27 markers flanking FMR1.
Abstract: The fragile X syndrome is the result of amplification of a CGG trinucleotide repeat in the FMR1 gene and anticipation in this disease is caused by an intergenerational expansion of this repeat. Although regression of a CGG repeat in the premutation range is not uncommon, regression from a full premutation (>200 repeats) or premutation range (50–200 repeats) to a repeat of normal size (<50 repeats) has not yet been documented. We present here a family in which the number of repeats apparently regressed from approximately 110 in the mother to 44 in her daughter. Although the CGG repeat of the daughter is in the normal range, she is a carrier of the fragile X mutation based upon the segregation pattern of Xq27 markers flanking FMR1. It is unclear, however, whether this allele of 44 repeats will be stably transmitted, as the daughter has as yet no progeny. Nevertheless, the size range between normal alleles and premutation alleles overlap, a factor that complicates genetic counseling.
30 citations
TL;DR: Using the repeat expansion detection method, this work found no significant increase in the frequency of CAG repeat expansion among 46 unrelated PD probands compared with controls, and did not find evidence for C AG repeat expansion between generations in 11 different PD families that exhibit anticipation in age at onset.
Abstract: In some kindreds, familial Parkinson's disease (PD) exhibits genetic anticipation. Thus, we postulated that familial PD in certain kindreds may be associated with a CAG repeat expansion. However, using the repeat expansion detection method, we found no significant increase in the frequency of CAG repeat expansion among 46 unrelated PD probands compared with controls. Nor did we find evidence for CAG repeat expansion between generations in 11 different PD families that exhibit anticipation in age at onset.
30 citations
30 citations
TL;DR: Retinal degeneration is variable in late onset patients and neuromuscular features are important in patients with early onset, which seems related to age at onset in autosomal dominant cerebellar ataxia type II.
Abstract: OBJECTIVES: To investigate relations between clinical and neuropathological features and age of onset, presence of anticipation, and genetic linkage in autosomal dominant cerebellar ataxia type II (ADCA II). METHODS: The natural history of ADCA II was studied on the basis of clinical and neuropathological findings in two pedigrees and genetic linkage studies were carried out with polymorphic DNA markers in the largest, four generation, pedigree. RESULTS: Ataxia was constant in all age groups. Retinal degeneration with early extinction of the electroretinogram constituted an important component in juvenile and early adult (< 25 years) onset but was variable in late adult presentation. Neuromuscular involvement due to spinal anterior horn disease was an important contributing factor to illness in juvenile cases. Postmortem findings in four patients confirm the general neurodegenerative nature of the disease, which includes prominent spinal anterior horn involvement and widespread involvement of grey and white matter. Genetic linkage was found with markers to chromosome 3p12-p21.1 (maximum pairwise lod score 4.42 at D3S1285). CONCLUSIONS: The sequence of clinical involvement seems related to age at onset. Retinal degeneration is variable in late onset patients and neuromuscular features are important in patients with early onset. Strong anticipation was found in subsequent generations. Linkage of ADCA II to chromosome 3p12-p21.1 is confirmed.
30 citations
TL;DR: Anticipation is supported in this specific set of families and, if it is confirmed by other studies, a role for trinucleotide repeat sequences may be considered to account for the familial aggregation of panic disorder.
Abstract: OBJECTIVE: Anticipation (i.e., the decrease in age at onset or the increase in severity of a disorder in successive generations) has recently been reappraised as a key to understanding the genetics of some familial illnesses. The purpose of this study was to search for possible anticipation in panic disorder. METHOD: Thirty-eight unilineal, multigenerational families with multiple directly interviewed members who had panic disorder were compared across two successive generations for 1) age at the first panic attack, 2) age at the onset of panic disorder, and 3) the highest degree of agoraphobia ever experienced, as a tentative index of severity of illness. Intergenerational pairwise comparisons were implemented according to four different sampling schemes: random pairs, random transmitting pairs, all possible pairs, and all possible transmitting pairs. RESULTS: Life table analyses showed a significant decrease in the time before the first episode of panic and onset of panic disorder from the older to the ...
30 citations