Endocrinology and diabetes
Shibley Rahman, Avinash Sharma in A Complete MRCP(UK) Parts 1 and 2 Written Examination Revision Guide, 2018
Common causes of primary hypogonadism include:Klinefelter’s syndrome. This condition results from a congenital abnormality of the sex chromosomes, X and Y. A male normally has one X and one Y chromosome. In Klinefelter’s syndrome, two or more X chromosomes are present in addition to one Y chromosome. The Y chromosome contains the genetic material that determines the sex of a child and related development. The extra X chromosome that occurs in Klinefelter syndrome causes abnormal development of the testicl*s, which in turn results in underproduction of testosterone.Mumps orchitis If a mumps infection involving the testicl*s in addition to the salivary glands (‘the mumps orchitis complex’) occurs during adolescence or adulthood, long-term testicular damage may occur. This may affect normal testicular function and testosterone production.haemochromatosisinjury to the testicl*streatment for cancerageing
Genetic Principles
Gail S. Anderson in Biological Influences on Criminal Behavior, 2019
The X and Y chromosomes not only determine sex but also carry other genes. The X chromosome is quite large and carries many genes, but the Y chromosome is very small and carries only a few genes. If a gene is on a sex chromosome, it is said to be sex linked. Usually, this means that it is on the X chromosome, simply because it has more genes. We know about a few such sex-linked genes, and some cause diseases in humans. We know the most about genes that cause diseases, because they are of most interest to us. Genes that are involved in hair or eye color are not so vital and therefore do not get the same research attention. Two classic examples of sex-linked conditions are color blindness and hemophilia.2 They are both usually found in men and only very rarely in women. It is quite common for men to be color blind but not for women, and the same is true for hemophilia. The reason is that both diseases are caused by recessive genes. The dominant form is normal. If you think back about the earlier examples relating to dominant and recessive genes, you will see that people only express the recessive gene if they have two recessive alleles. If they had two dominant alleles, or one of each, then the recessive gene would not be expressed, just as the purple flower “hid” the white flower. Also, these disease-causing recessive genes are usually fairly rare, so the allele ratio may be 98% normal dominant and 2% disease-causing recessive.
Genetic Factors in Parkinson's Disease
Lucien Côté, Lola L. Sprinzeles, Robin Elliott, Austin H. Kutscher in Parkinson's Disease and Quality of Life, 2014
To explain what “autosomal dominant” means it is necessary to briefly review some elements of genetics. In the nucleus of every cell in human beings are 23 pairs of chromosomes. They are called chromosomes, meaning “colored bodies,” because they take the color of certain chemical stains which render them visible when viewed under a microscope. They exist in pairs, one received from each parent. Two of the chromosomes, named “X” and “Y,” are the sex chromosomes. The remaining 22 pairs are called “autosomes.” Males have a Y chromosome inherited from their fathers and an X inherited from their mothers. Females have two X chromosomes, one inherited from each parent. We can infer that the gene for PD cannot be on either of the sex chromosomes since the disease affects men and women with equal frequency. Hence, PD is an “autosomal” disorder.
Mediterranean Y-chromosome 2.0—why the Y in the Mediterranean is still relevant in the postgenomic era
Published in Annals of Human Biology, 2018
Maarten H. D. Larmuseau, Claudio Ottoni
The human Y-chromosome differs markedly from the other chromosomes in inheritance, size, genomic structure, content and evolutionary trajectory (Jobling etal., 2013). It is the sex-determining chromosome, which is essential for male sexual differentiation and spermatogenesis, and evidence for its role in human biology beyond male reproduction is growing (Massaia & Xue, 2017). Between the two pseudoautosomal regions (PAR) of XY sequence hom*ology at the tips of the arms, which are required for proper chromosome segregation during meiosis (Mensah etal., 2014), the male-specific region of the Y-chromosome (MSY) is passed down from father to son and escapes the reshuffling effects of crossing-over. This MSY region, also known as the non-recombining region of the Y-chromosome (NRY), has a strong structural complexity with many repeated elements and segmental duplications, which covers ∼35% of its length, and only contains ∼78 protein-coding genes (Jobling & Tyler-Smith, 2017; Skaletsky etal., 2003).
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 etal. 2015; Yin etal. 2022). Moreover, Y-STR haplotype analysis is increasingly employed in male relative identification (Ballantyne etal. 2010; Adnan etal. 2016), kinship analysis, familial searching (Foster etal. 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 etal. 2008; Huang etal. 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.
