Biological Dimensions of Difference
Christopher J. Nicholls in Neurodevelopmental Disorders in Children and Adolescents, 2018
Gregor, as he was named by the friars, went on to develop two important conclusions from his work. The first conclusion, which he called the Law of Segregation, was that there are some traits that seem to be more powerful and would dominate other traits in the cross-breeding. This was contrary to conventional wisdom at the time, which was that traits would dilute each other through their combination. The other conclusion, which he termed the Law of Independent Assortment, established that some traits were passed on independently of other traits. Although he did little to publicize his work, and much of his work was initially misunderstood, Gregor Mendel’s research became the foundation for the understanding of genetics and much of the foundation of biology (Mendelian Inheritance. n.d.).
Introduction to Molecular Biology
Martin G. Pomper, Juri G. Gelovani, Benjamin Tsui, Kathleen Gabrielson, Richard Wahl, S. Sam Gambhir, Jeff Bulte, Raymond Gibson, William C. Eckelman in Molecular Imaging in Oncology, 2008
In 1865, Gregor Mendel, an Austrian monk, was the first to publish a theory about genetic rules that govern inheritance (5). By conducting crossbreeding experiments on pea plants, he was able to propose a generalized set of rules, now known under the name of Mendel’s law of heredity or Mendelian inheritance. He postulated that the transmission of hereditary characteristics from parent organisms to their progeny are governed by discrete units that are transmitted from generation to generation, even if some of these units are not expressed as visually observable trait in every generation. These units were the first report of the discovery of what we now call genes. He also postulated that for each characteristic, an organism inherit two alleles, one from each parent. Unfortunately, the results of Mendel’s work were initially very controversial and neglected by the scientific community until the “rediscovery” of the theory in 1900, by three European scientists Hugo de Vries, Carl Correns, and Erich von Tschermak.
Molecular Genetic Diagnosis of Human Malignant Hyperthermia
S. Tsuyoshi Ohnishi, Tomoko Ohnishi in Malignant Hyperthermia, 1994
Traits and diseases that are not associated with chromosomal rearrangements or are not consistent with simple Mendelian inheritance may arise from the interaction of multiple genes, each with an additive effect. Multifactorial or polygenic inheritance, which is frequently apparent only in the setting of specific environmental factors, has been suspected in a subset of MH pedigrees.31 In multifactorial genetic disease each first degree relative of an affected proband has roughly a 5% chance of being affected. At present, molecular genetic tools appropriate for mapping multiple genetic loci responsible for the inheritance of quantitative traits require controlled breeding of large sibships. Optimism for understanding the inheritance of multifactorial disease at the nucleotide level rests on the possibility that loci are shared between single and oligogenic disorders, and that animal models of human multifactorial disease can be discovered.
A Novel Mutation p.S93R in CRYBB1 Associated with Dominant Congenital Cataract and Microphthalmia
Published in Current Eye Research, 2020
Aixia Jin, Yu Zhang, Dongchang Xiao, Mengqing Xiang, Kangxin Jin, Mingbing Zeng
We found a four-generation family with inherited congenital cataract in the rural area of Hainan island, China (Figure 2a and Table 1). The family has a relatively small pedigree size, including 5 affected and 5 unaffected individuals, 3 of whom passed away at normal age. The disease type conforms to the classic dominant Mendelian inheritance. All affected individuals have cataracts in both eyes at birth. Only 5 individuals (3 affected, 2 unaffected) were available for the clinical examinations and thus included in this study. The juvenile patients (IV:1 and IV:2) have nuclear cataracts in both eyes. Overall, lens opacification increased with age in all affected individuals. Additionally, all the examined patients have microphthalmia and microcornea in both eyes, indicating that the cataract is companied by developmental defects in the eye.
Testing for genetic contributions to infertility: potential clinical impact
Published in Expert Review of Molecular Diagnostics, 2018
Csilla Krausz, Francesca Cioppi, Antoni Riera-Escamilla
To date, 35 candidate genes in cHH have been identified [2,4], and are implicated either in the development/migration of the GnRH neurons (typically causing KS) or in the neuroendocrine regulation of GnRH secretion or action (typically causing normosmic cHH) (Table 1). cHH shows three main peculiarities: i) in some cases the same gene (i.e. FGFR1, PROKR2) may cause both KS and normosmic cHH, implying that from a genetic point of view a clear distinction between the two clinical entities cannot be established; ii) it does not follow the rules of Mendelian inheritance since in about 20% of cases there is a digenic/oligogenic inheritance, i.e. two heterozygous mutations in two or more candidate genes; iii) although cHH has traditionally been considered a life-long condition, the ‘reversibility’ of the gonadotrophin deficiency has been described in about 10–15% of patients [5].
Congenital fibrinogen disorder caused by digenic mutations of the FGA and FGB genes
Published in Hematology, 2020
Xiong Wang, Ning Tang, Na Shen, Yanjun Lu, Dengju Li
For some disorders, the discovery of rare genetic variants and the observation of familial co-segregation in some cases result in the perception that Mendelian inheritance may apply. However, recent advances in genetic tests have revealed several disorders beyond the One Gene-One Disease paradigm, indicatinga more complex inheritance and pleiotropy in heritable disorders [13]. Cerrone et al., reported that oligogenic or polygenic genetic variants contributed to inheritable cardiac disorders [14]. Monogenic, polygenic, and oligogenic inheritance were found in familial hypercholesterolemia [15]. In polygenic or oligogenic inheritance, one variant may function as genetic modifiers determining the ultimate disease manifestations. Kuuluvainen et al., reported that the penetrance of SOD1 p.Ala90Val mutation was modulated by other variants, indicating oligogenic basis of sporadic ALS [16]. Within bleeding, thrombotic and platelet disorders, Downes et al., reported 3.9% and 1.8% patients harbored oligogenic variants for the thrombotic and coagulation classes in a large cohort in UK recently [17]. This is the first time we have identified oligogenic mutations of the FGA and FGB genes for CFD in Chinese.
Related Knowledge Centers
- Classical Genetics
- Evolution
- Heredity
- Population Genetics
- Quantitative Trait Locus
- Boveri–Sutton Chromosome Theory
- Natural Selection
- Pea
- Blending Inheritance
- Complex Traits