China
Africa
Explore chapters and articles related to this topic
Genetics and exercise: an introduction
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Claude Bouchard, Henning Wackerhage
We have already mentioned that DNA sequence variants influence body height, strength, VO2max trainability or disease risk. We will now discuss how variations in the DNA sequence occur, the different types of DNA variants and their frequency in human populations. But first we need to explain the vocabulary used to define DNA variants. A mutation is an event that changes a DNA sequence. The consequence of a mutation is a DNA variant. For example, a mutation may change a “…CTGT…” to a “…CTAT…” sequence resulting in a G/A DNA variant. Alleles are DNA variants of a given sequence. For example, assume that 20% of a population have a “CTGT” and 80% a “CTAT” DNA sequence in the myostatin gene (important in muscle mass regulation, covered in Chapter 4 and 8); the CTGT variant would be the minor (frequency) allele, whereas the CTAT variant would be the major (frequency) allele. Alleles with a frequency of less than 1% are referred to as rare alleles, whilst those in the range of 1–5% are known as low frequency alleles. DNA variants with a minor allele carried by 5% and more of the population are labelled as common alleles. If a one-base substitution occurs in at least 1% of a population, then it is termed a single-nucleotide polymorphism and is abbreviated as SNP. SNPs are the most studied DNA variants.
Cancer Biology and Genetics for Non-Biologists
Published in Trevor F. Cox, Medical Statistics for Cancer Studies, 2022
For a chromosome, the types of mutation are, Deletion of part of the chromosome.Duplication of a segment of the chromosome.Inversion where a segment of the chromosome is reversed.Translocation where a segment of a chromosome attaches to another chromosome.
Radiation Injuries to Human Fetuses
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
Radiation increases the risk of nondisjunction (uneven distribution of chromosomes in the daughter cells) during mitosis in a subsequent pregnancy. Table 15.10 shows that young females who had received diagnostic radiation (0.5–7 rads, gonadal dose) before conception had ten times more aneuploidy children (one excess or one deficient chromosome) than those who received no irradiation.62 A gonadal dose of about 5 rads to the woman before conception also produces an eye defect in subsequent children.63 The estimated minimal spontaneous frequency of point mutation per generation due to naturally occurring mutation-causing agents is 2%. This mutation rate includes less than half of the gross abnormalities, such as mental defects, hematologic and endocrine defects, defects in vision and hearing, cutaneous and skeletal defects, and defects in the GI tract that occur at birth. It does not include those mutations whose effects are less drastic. A gonadal dose of 3 R, which may be received by medical exposure over 30 years, would increase the number of point mutations of all degrees by about 1%.64
Investigation of ocular involvement in patients with Fabry disease
Published in Annals of Medicine, 2023
Yuan Wu, Wenbo Zhang, Xuyang Yao, Wenjing Song, Yawen Zhao, Yun Yuan, Wei Zhang
Forty-five FD patients (33 hemizygote/males and 12 heterozygote/females) attended the Department of Ophthalmology, Peking University and were included in this study between January 2014 and December 2021. All patients had their diagnosis confirmed by DNA testing that revealed the presence of an α-galactosidase A mutation. The mutation types included substitutions, deletions and duplications. Among them, 33 patients had substitution mutations, accounting for 73.3%, 10 patients had deletion mutations, accounting for 22.2% and 2 patients had duplication mutations, accounting for 4.4%. Informed consent was obtained from all participants, and the study protocol was approved by the Institutional Review Board of Peking University First Hospital; the study was performed in accordance with the tenets of the Declaration of Helsinki.
Fallopian tube cancer– challenging to diagnose but not as infrequent as originally thought
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Jasmin Hundal, Nerea Lopetegui-Lia, William Rabitaille
Genetic testing can also be undertaken to identify any familial genetic mutation or the onset of sporadic mutations. Primary care physicians are recommended to utilize familial risk assessments, such as Ontario Family History Assessment Tool, Manchester Scoring System, Pedigree Assessment Tool, International Breast Cancer Intervention Study Instrument, 7-Question Family History Screening Tool, as screening tools to assess the risk of a BRCA1 and BRCA 2 mutation [11]. However, trained health professionals should perform genetic counseling about mutation testing. According to the American Cancer Society, genetic testing is recommended for women who have a known family history of BRCA mutation, women diagnosed with ovarian cancer, pancreatic cancer, family history of breast cancer at a younger age, more than one family member with breast cancer and breast cancer in a male family member [12].
Genetic effects of non-ionizing electromagnetic fields
Published in Electromagnetic Biology and Medicine, 2021
Supplements 1 and 2 show that the majority of studies reported genetic effects of EMF (66% for RFR and 79% for static/ELF-EMF). Thus, it is safe to conclude that genotoxic effects of EMF have been reported. The most common effects found are: DNA strand breaks, micronucleus formation, and chromosomal structural changes. There are not many studies on mutation. Thus, it is not known whether these genotoxic effects transform into mutation and involved in carcinogenesis. Interestingly, available data do not suggest mutagenic effect after RFR exposure (Chang et al., 2005; Meltz et al., 1990; Ono et al., 2004; Takahashi et al., 2002); whereas most static/ELF-EMF studies (Chahal et al., 1993; Mairs et al., 2007; Miyakoshi, 1997; Miyakoshi et al., 1998, 1996; Potenza et al., 2004; Wilson et al., 2015) suggested some mutagenic effects. Another interesting speculation is that ELF EMF acts as a promoter of cancer in the presence of an initiator by modulation of signaling pathways involved free radicals and apoptosis (Lacy-Hulbert et al., 1998). Such a possibility has not been well investigated.