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Cystic Fibrosis
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
Alexander G. Bearn, Β. Shannon Danes
The frequency of the disease coupled with its lethality raises the question of whether, under certain environmental circumstances, powerful selective forces operate that favor the heterozygote. Indeed it has been suggested that the striking racial variation may have its root cause in the operation of selective factors acting unfavorably in hot climates. Although no convincing evidence for such presumed heterozygous advantage has been advanced, it can be calculated that a mere 2% advantage of the heterozygote is sufficient to achieve genetic equilibrium; the likelihood of being able to identify such a small advantage is remote.
Hereditary Malignant Melanoma and the Fammm Syndrome
Published in Henry T. Lynch, Ramon M. Fusaro, Hereditary Malignant Melanoma, 2019
Henry T. Lynch, Ramon M. Fusaro, Lavonne Johnsen, Jane F. Lynch
Traupe et al.56 have argued that a polygenic model, as opposed to autosomal dominant inheritance, may provide a better explanation for the genetics of the FAMMM syndrome. This supposition has been based on an apparent lack of genetic equilibrium between newly arising and eliminated mutations which these investigators believe is not compatible with the postulated autosomal dominantly inherited mechanism for the FAMMM.
J.B.S. Haldane (1892–1964)
Published in Krishna Dronamraju, A Century of Geneticists, 2018
In Part VIII of his series of papers on the mathematical theory of natural selection, Haldane’s (1931) concept of “Metastable populations” stands out. He wrote: “Almost every species is, to a first approximation, in genetic equilibrium; that is to say no very drastic changes are occurring rapidly in its composition. It is a necessary condition for equilibrium that all new genes which arise at all frequently by mutation should be disadvantageous, otherwise they will spread through the population. Now each of two or more genes may be disadvantageous, but all together may be advantageous.” Haldane cited the observation of Gonsalez, in 1923, who found that, in purple-eyed Drosophila melanogaster, arc wing or axillary speck (both due to recessive genes) shortened life, but together, they lengthened it.
Human Leukocyte Antigen Polymorphism HLA-A*24:02 is Associated with Acute Liver Disease in HBV-Infected Han Chinese Adults
Published in Immunological Investigations, 2023
Dongliang Li, Zhiyu Zeng, Shumin Zhao, Xiulan Ao, Haicong Wu, Zhiqiang Zhang, Shian Zhang, Xiaolin Zhou, Xiaohui Miao
The aim of HWE testing was to evaluate whether the distribution of gene loci in the control group meets the requirements of genetic equilibrium and to assess the reliability of the population genetic data. The non-compliance of the HLA-A*24:02 allele with HWE is related to the sample size and also to the population genetic structure. The number of patients enrolled reached the sample size estimated by the study design, indicating that the statistical requirements would be met. Of the three alleles, HLA-A, HLA-B and DRB1 tested in the control group, two were in equilibrium, which demonstrated that the population investigated was in compliance with HWE in general. The ideal population genetic model has four hypothetical prerequisites: 1. infinite population size; 2. random mating; 3. absence of mutations; and 4. absence of mass migration and natural selection. However, in practice the conditions for this ideal population cannot be fully satisfied. This study comprised a geographical population and HLA-A is associated with the immune response, so different alleles may present different immune responses in humans, and if certain alleles are favored by natural selection, they will disrupt the HWE because they produce changes in gene frequencies. Alternatively, the non-compliance may be related to genetic drift, where allele frequencies may fluctuate randomly in our geographical population, leading to deviations from HWE.
The Impact of STAT3 rs1053005 Variation on Type 1 Diabetes Mellitus Susceptibility: Association Study and in Silico Analysis
Published in Immunological Investigations, 2022
Maryam Zandi, Vaha Akbary Moghaddam, Zivar Salehi, Farhad Mashayekhi, Setila Dalili
All variables in this study were statistically analyzed using the statistical analysis software SPSS version 19.0 (IBM Corp., Armonk, NY USA). Mean and standard deviation was represented as continuous variables and the qualitative data were represented in frequencies and percentages. The consistency of genotype frequencies with the Hardy-Weinberg equilibrium (HWE) was tested using a χ2 test on a contingency table of observed vs. expected genotype frequencies in controls and patients. A P-value ≥0.05 indicated that the sample reached genetic equilibrium with good population representativeness. Statistical analysis between cases and controls using genotyping data with odds ratios (OR) and 95% confidence intervals (CI) was performed with both genotype and allele frequencies including dominant [(aa+Aa) vs. AA], co-dominant (aa vs. AA and Aa vs. AA), recessive [aa vs. (AA+Aa)], and overdominant [Aa vs. (aa + AA)] modes of inheritance.
MTHFR polymorphism as a predictive biomarker for gastrointestinal and hematological toxicity in North Indian adenocarcinoma patients
Published in Journal of Chemotherapy, 2022
Harleen Kaur Walia, Navneet Singh, Siddharth Sharma
For the MTHFR 677 C > T polymorphism, 200 (79.05%) patients were homozygous for the CC genotype, whereas 49 (19.37%) were heterozygous (CT) carriers and 4 (1.58%) were variant homozygotes (TT) (Table 2). Whereas for the MTHFR 1298 A > C polymorphism, 121 (47.83%) patients were harboring homozygous AA genotype, 106 (41.89%) were heterozygous AC, and 26 (10.28%) were homozygote variant (CC). The genotypic frequencies of MTHFR 1298 A > C (χ2 = 4.13, df = 1; p = 0.99) and MTHFR 677 C > T polymorphism was (χ2 = 0.15, df = 1; p = 0.69). Thus, genotypic distributions for both the polymorphic sites followed the Hardy-Weinberg equilibrium with a p-value >0.05 (Table 2). Thus, these samples could represent a Mendelian population with a genetic equilibrium.