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Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Screening tests are a routine part of medical care, with the goal of early identification and treatment of specific and common diseases. For genetic diseases, population screening involves not only affected individuals, but also additional family members. Screening for genetic disease has been defined as the “search in a population for persons possessing certain genotypes that (i) are already associated with disease or predisposition to disease or (ii) may lead to disease in their descendants” (39). As outlined in the previous section, newborn screening for metabolic diseases exemplifies the first type of screening, which will result in proper identification of infants with these disorders and institution of treatment. Other examples include presymptomatic genetic testing for Huntington disease, breast cancer, or colon cancer.
An Approach to Inherited Pulmonary Disease
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
The term phenotype can be applied to any property observable in an organism or in specimens obtained from an organism. By genetic analysis phenotypes can be attributed to the action of certain genes whose presence in an individual organism is inferred from the phenotype and the pedigree. The complement of genes present in an organism is called the genotype. In diploid organisms such as humans there are two complete sets of the genes carried on the autosomes, those chromosomes other than the X and Y. A pair of genes occupies a specific place in the genome called a locus. Commonly the term genotype is used in reference to only the two genes at the one locus relevant to a specific phenotype. Alternative forms of a gene which can occupy the same locus are called alleles. An individual who has two different genes at one locus is said to be heterozygous at that locus, or a heterozygote. An individual who has two copies of the same gene at one locus is said to be homozygous at that locus, or a homozygote.
Genomics and Hearing Loss: Toward a New Standard of Care?
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
The genotype of an individual is determined by alleles (variant form of a gene) that are received from the individual’s parents. The alleles contribute to the organism’s phenotype, which is the combination of an individual’s observable characteristics or traits, such as its morphology, development, physiological properties, and behavior. The phenotype is the result of the expression of an individual’s genotype, but also of the influence of environmental factors and the interactions between the two. The alleles of an individual control if a trait is dominant or recessive. Traits are dominant if only one copy of the allele is required for expression of the trait. Traits are recessive if two copies of an allele are required for expression of the trait. X-linked traits are those controlled by an allele that is carried on the X chromosome, while autosomal characteristics are controlled by alleles located on any “nonsexual” chromosome, that is, excluding the chromosomes X or Y. For any given phenotypical characteristic, an individual inherits one gene from each parent so that the individual has a pairing of two genes. If the two alleles that form the pair for a trait are identical, then the individual is said to be homozygous for that characteristic and if not, the individual is then heterozygous.
An Evaluation of Gene-Diet Interaction Statistical Methods and Discovery of rs7175421-Whole Grain Interaction in Lung Cancer
Published in Nutrition and Cancer, 2022
Jun Tao, Aya El Helali, James C. Ho, Wendy W.T. Lam, Herbert Pang
The probabilities of controls were set as a vector denoting the counts of G-E- control, G-E + control, G + E-control, and G + E + control. The probabilities of cases were set as a vector denoting the counts of G-E- cases, G-E + cases, G + E- cases, and G + E + cases. The probabilities in each vector should add up to 1. The two vectors have some mutual correlations with each other, which includes 1) the odds ratio (OR) for gene and diet in the control population (ORGE); 2) the prevalence of dominant genotype in the controls (PG); 3) the prevalence of upper half intake of whole grains in the controls (PE); 4) the OR for the disease-gene association (OR10); 5) the OR for the association between whole grain and lung cancer (OR01); 6) the interaction effect: φ = OR11/(OR10*OR01). The parameters of mutual correlation are generated by the real dbGaP dataset.
Association of NOD1, NOD2, PYDC1 and PYDC2 genes with Behcet’s disease susceptibility and clinical manifestations
Published in Ophthalmic Genetics, 2021
Ayca Kocaaga, Gunes Cakmak Genc, Sevim Karakas Celık, Rafet Koca, Ahmet Dursun
We also subsequently investigated the association in three SNPs (NOD1 and NOD2 genes) and in one SNP (PYDC2 gene) with clinical manifestations except oral oral aphthae and genital ulcer of BD. We compared our findings between the positive (present) and negative (absent) patients in terms of the clinical manifestations; as well as between the positive patients and the control groups. Genotype distributions among the patient groups were analyzed based on the autosomal recessive inheritance model. In the NOD1 rs2075820 (G/A) polymorphism, the frequency of AA genotype was higher (35.6% vs 14.3) in patients with cardiovascular involvement compared to patients without cardiovascular involvement (p = .044, OR = 4.286; CI = 1.089–16.868, Table 5). There was not any statistically significant difference between groups in the rs2075820 polymorphism for other clinical findings.
Whole blood dynamic platelet aggregation counting and 1-year clinical outcomes in patients with coronary heart diseases treated with clopidogrel
Published in Platelets, 2021
Huaibin Wan, Weichao Han, Zhihao Wu, Zhenbang Lie, Daqiang Li, Shaohui Su
Genomic DNA was isolated from peripheral whole-blood specimens using the QIAamp Blood Kit (Qiagen, Hilden, Germany) according to the manufacturer’s instructions. Genotyping for known variants of CYP2C19*2, *3, and *17 were performed using a Pyro sequencing reaction general kit (3G Biotech, Changsha, China) and a detection system (QIAGEN PyroMark Q24 vacuum workstation, Germany). Base numbering and allele definitions follow the nomenclature of the Human Cytochrome P450 (CYP) Allele Nomenclature Committee (www.cypalleles.ki.se). The SNP genotypes were translated into star-allele genotypes. The combination of two alleles comprises a genotype. The patients were classified as extensive metabolizers, defined as two alleles conferring normal activity, near-normal activity, or individuals with an allele conferring decreased activity and a CYP2C19*17 (EMs: *1/*1, *1/*17, *17/*17, *2/*17, *3/*17). Reduced metabolizers defined by at least one reduced function allele except integrating with a CYP2C19*17 (RMs: *1/*2, *1/*3, *2/*2, *2/*3, *3/*3).