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Approach to women with a previous child with a genetic disorder
Published in Minakshi Rohilla, Recurrent Pregnancy Loss and Adverse Natal Outcomes, 2020
Disorders that are caused by genes located on the sex chromosomes (X or Y chromosome) are referred to as sex-linked disorders. These include X-linked recessive and X-linked dominant. X-linked recessive:Females are not usually affected as they have two X chromosomes. For a carrier female, there is a 50% chance that her son will inherit the disease and a 50% chance her daughter will be a carrier. For an affected female, all of her daughters will be unaffected carriers and all of her sons will be affected. Affected males transmit the disease allele to all of their daughters but not to their sons. Examples include Duchenne muscular dystrophy and fragile X syndrome.X-linked dominant:A few diseases may be so severe in affected boys that the pregnancy miscarries prior to disease recognition; therefore, only affected girls are born with the disease. Examples include Aicardi syndrome and Rett syndrome.
Misconceptions, Experimental Design, and Behavioral Genetics
Published in Gail S. Anderson, Biological Influences on Criminal Behavior, 2019
Let us look at the history, the facts, and the fallacies. All people have 46 chromosomes, 44 of which are somatic and 2 of which are the sex chromosomes. Women have two X chromosomes, and men have one X and one Y chromosome, so women are denoted as XX and men as XY; this is the normal configuration. The Y chromosome is considered the “male” chromosome because only men have it, but they have an X as well. You could say that they have one male and one female chromosome, but this would not be accurate. The Y chromosome does not mean “male”; XY together indicates a male (there are no people who are YY).
Genetic counselling in Mendelian disorders
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Since virtually no serious human diseases are known to be borne on the Y chromosome, sex linkage is equivalent to X linkage, so far as genetic counselling is concerned. (An example of a disorder that can be transmitted on the Y chromosome is the Leri-Weill dysostosis caused by mutation in the SHOX gene on the pseudoautosomal portions of the two sex chromosome short arms: see later discussion.) Microdeletions of the Y chromosome are implicated in male infertility but, except through the use of ICSI (see the discussion on infertility treatments), are not usually transmitted to the next generation.
Features of Turner syndrome in patients managed at the adult endocrinology clinic, Steve Biko Academic Hospital
Published in Journal of Endocrinology, Metabolism and Diabetes of South Africa, 2023
Patients may present with different karyotypes, all lacking X-chromosome material. It can be divided into two major groups: total or partial absence of the p-arm of the second X-chromosome. Most females with Turner syndrome (50%) are missing an entire sex chromosome, 20% have a mosaic karyotype (most commonly 45,X/46,XX) and 25% have a partial deletion of one X-chromosome.6 This differed from our population, in which the majority (64.7%) had a mosaic karyotype. In 75–80% of cases, the loss or partial loss of the X-chromosome is from the male gamete.5 In addition to these karyotypes, 0–61.1% of women have varying amounts of Y-chromosome material, 3% of these women being 45,X/46, XY. Karyotype analysis is essential in risk stratification as the presence of Y-chromosome material has been shown to increase the risk of gonadal malignancies.1,7 None of the patients enrolled in the study had any Y-chromosome material.
Genetic diversity of 23 Y-STR loci of the Lisu ethnic minority residing in Chuxiong Yi Autonomous Prefecture, Yunnan province, Southwest China
Published in Annals of Human Biology, 2023
Xiufeng Zhang, Hecheng Zheng, Chengjing Liu
The Y chromosome is male-specific, paternally inherited, and haploid for the majority of its length because it is immune to meiotic recombination. This region is passed down from father to son and remains unchanged unless a mutation event occurs. As a result, the Y chromosome contains a record of all the mutational events that occurred among his ancestors, reflecting the history of his paternal lineage. It is possible to reconstruct the histories of paternal lineages by comparing Y-STRs DNA polymorphism (Jobling and Tyler-Smith 1995). The interest in Y chromosome polymorphisms has steadily increased over the last few decades, not only because of its application in human and evolutionary genetics, but also because of its interest in forensics, particularly in cases where standard autosomal DNA profiling is not informative. Population data on Y-STRs is essential for crime scene investigations. Haplotypes composed of Y-STRs are used to characterise the paternal lineages of unknown male trace donors, particularly in sexual assault cases involving mixed stains, when both males and females contributed to the same trace (Dekairelle and Hoste 2001; Purps et al. 2015; Yin et al. 2022). Moreover, Y-STR haplotype analysis is increasingly employed in male relative identification (Ballantyne et al. 2010; Adnan et al. 2016), kinship analysis, familial searching (Foster et al. 1998), inferring paternal bio-geographical ancestry (Phillips 2015), and also for the analysis of migration (Underhill and Kivisild 2007), settlement, or mating structure of human populations.
Genetic analysis of 23 Y-STR loci in the Va population from Yunnan Province, Southwest China
Published in Annals of Human Biology, 2023
Jing Yuan, Lei Huang, Yuan Yin, Xiufeng Zhang
For most of its length, the Y chromosome is uniparentally inherited and escapes recombination. Thus, variation arises only by the sequential accumulation of new mutations, reflecting the history of paternal lineage. Recently, Y-chromosomal short tandem repeat (Y-STR) polymorphism has become increasingly interesting, not only for population genetics or evolutionary studies but also for forensics, particularly in cases where standard autosomal DNA profiling is not informative. Haplotypes composed of Y-STRs are very useful both for excluding suspects from involvement in a crime by demonstrating non-matching haplotypes and for identifying groups of male relatives belonging to the same paternal lineage by demonstrating haplotype matches (Leite et al. 2008; Huang et al. 2011). The PowerPlex Y23 (Promega Corporation) system has been used to investigate approximately 100,000 Y-STR reference databases from various populations around the world on the YHRD website, however, population data for the Chinese Va are lacking, and the genetic relationships between the Va minority and other Chinese populations or adjacent Asian populations are unclear. In this study, we presented allele frequencies and haplotype distribution of 23 Y-STR loci in the Va group from Yunnan Province, China, and compared pairwise genetic distances with the other populations.