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Genetics and exercise: an introduction
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Claude Bouchard, Henning Wackerhage
From a biological or behavioural perspective, there are two types of traits or characteristics of an individual. Some traits are binary such as either having a disease like Duchenne Muscular Dystrophy or not. These types of disease often depend on one gene, which can be either normal or defective. Other traits become mature under the influence of a number of genes: the eight genes (and perhaps more) contributing to eye colour would be a good example.
Cancer Biology and Genetics for Non-Biologists
Published in Trevor F. Cox, Medical Statistics for Cancer Studies, 2022
A gene can have different codings, and these variants are called alleles. One allele is inherited from your mother and one from your father for each gene, and these determine your physical traits (phenotype), such as hair colour, height, etc. The combination of the alleles that you have inherited make up your genotype, but we can also use this term for a particular gene. If there are two possible alleles for a gene, A and a, there are three possible genotypes, AA, Aa and aa, depending on which alleles you inherited. For example, the OCA2 gene on chromosome 15 is associated with melanin production, which is a pigment for hair, eye and skin colour. A might be the allele for brown eyes and a for blue eyes. A is dominant and a is recessive, and so individuals with AA and Aa will have brown eyes, and individuals with aa will have blue eyes. But eye colour is not quite so simple as this as other genes are also involved. The allele that codes for the most common phenotype is called the wild type allele.
Genetic Limitations to Athletic Performance
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Traditionally, in high schools we are taught that genetic traits are simple and follow Mendelian rules of inheritance. This implies that there is a gene for each trait with simple alternative versions, for example, the often-used example of the eye colour gene with blue and brown versions. Some traits are relatively simple. Rare disorders such as cystic fibrosis, sickle cell anaemia, and Huntington disease are the result of changes in single genes that can cause significant disease. However, the situation is rarely so simple. Even eye colour in reality involves differing versions of multiple genes (82). Height, a relatively simple aspect of physiology, is estimated to be determined by common variants in at least 700 genes—each with a small effect of only a few millimetres (85)—and rare variants in at least 83 genes with slightly larger effects of up to 2 centimetres (49). Other traits are also determined by multiple genes with small effects. For example, ∼900 genes are involved in determining the risk of hypertension (38). In fact, the vast majority of traits are complex and the result of the combined effects of many genes.
Faces: Identification and Biases
Published in Issues in Mental Health Nursing, 2020
Researchers in the psychology of eyewitness identification say that it is not bias or bigotry that makes it difficult for people to distinguish between people of another race. It is the lack of early and meaningful exposure to other groups that often makes it easier for us to quickly identify and remember people of our own ethnicity or race while we often struggle to do the same for others (Malpass, Ross, Meissner & Marcon, 2009). Starting when we are infants and young children, people become attuned to the key facial features and characteristics of those around them. Whites often become accustomed to focusing on differences in hair color and eye color. African-Americans grow more familiar with subtle shadings of skin color. It is a product of our perceptual experience. Minorities tend to be better at cross-race identification than whites in part because they have more extensive and meaningful exposure to whites than the other way around (Malpass et al., 2009). However, a meta-analysis of 30 years of research has shown that interracial contact accounts for only about 2% of the variance in own race bias across samples. Although negative racial attitudes are correlated with limited interracial contact, no relationship has been found between the ORB and racial attitudes, whether explicit or implicit (Johnson & Fredrickson, 2005).
Clinical albinism score, presence of nystagmus and optic nerves defects are correlated with visual outcome in patients with oculocutaneous albinism
Published in Ophthalmic Genetics, 2021
Alina V. Dumitrescu, Johnny Tran, Wanda Pfeifer, Sajag V. Bhattarai, Andrew Kemerley, Taylor V. Dunn, Kai Wang, Tod E. Scheetz, Arlene Drack
Eye color was available for 24 patients. Of these, 70.8% (17/24) were blue, 25% (6/24) were hazel, and 4.1% (1/24) were brown. Skin pigmentation in comparison to family members was available for 28 patients. Of these, only 32.1% (9/28) either had no skin pigmentation or were lighter than their family members. Of the 9 patients who either had no skin pigmentation or were noticeably lighter than family members, 8 had mutations found in albinism genes (5 had a complete phenotype, 3 had one mutation found). The remaining patients were Hispanic with noticeably lighter skin color than their mothers and had decreased BCVA (20/80 right eye, 20/100 left eye), small optic nerves, and nystagmus, but no iris transillumination and negative whole-exome genetic testing for albinism.
Blue-Light Filtering Intraocular Implants and Darker Irises Reduce the Behavioral Effects of Higher-Order Ocular Aberrations
Published in Current Eye Research, 2022
Lisa M. Renzi-Hammond, Billy R. Hammond
Upon arrival to the test site, uncorrected distance visual acuity (UDVA) was measured binocularly and monocularly in each test eye. UDVA of 20:40 or better in the test eye(s) was confirmed by a trained experimenter. Iris color was documented using a visual grading system24 based on judgements (matching a subject’s eye color to a series of 15 standardized iris images) by a single trained observer. The referents used by the grading system are a series of colored photographs of human irises sequenced according to their hue (CIE L*a*b color space) and measured lightness/darkness.