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Andrology
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Klinefelter’s syndrome (47,XXY) is the most frequent sex chromosome abnormality. Testosterone levels are normal or low. Androgen replacement may be needed in these men as they age. Germ cell presence and sperm production are variable in patients with mosaicism (46,XY/47,XXY). All patients of Klinefelter’s syndrome who have undergone sperm retrieval should have a long-term endocrinological review. Kallman syndrome is the most common X-linked disorder in infertility. It is X-linked recessive disorder (mutation in KALIG1 gene on Xp22.3). these patients have hypogonadotropic hypogonadism with anosmia and infertility. Spermatogenesis can be induced by hormonal treatment. Reifenstein syndrome is a state of partial androgen insensitivity with predominantly male phenotype including micropenis, perineal hypospadias and cryptorchidism. Complete androgen insensitivity syndrome (Morris syndrome), the phenotype is of female external genitalia and absence of pubic hair.
Aicardi Syndrome and Klinefelter Syndrome
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Klinefelter syndrome is the most common sex chromosomal disorder, affecting 1 in 500–700 newborn males who possess one or more extra X chromosomes. Clinically, the disease is characterized by primary infertility, atrophic testes, hypergonadotropic hypogonadism, gynecomastia, eunuchoidism, decreased facial and body hair, tall stature with eunuchoid body proportions, neurocognitive impairment, learning difficulties and behavior problems, and increased risk of autoimmune diseases and tumors (e.g., breast cancer and extragonadal GCT).
Clinical genetics
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Chromosomes are the basic packages of DNA in the nucleus of a cell. In humans who have a diploid set (denoted 2n) of chromosomes, there are 22 pairs of chromosomes in every cell, called the autosomes, and two sex chromosomes, giving a total of 46. Females have two homologous sex chromosomes, the X chromosomes, and males have one X and one Y chromosome. Each chromosome has a long arm, designated the q arm, and a short arm, designated the p arm. At the ends of each chromosome are the telomeres. Chromosomes consist of a DNA strand that is wound around histones and packaged with other proteins into a compact structure (Figure 5.2). Figure 5.3 shows the chromosomes of a normal male, as seen during metaphase in mitosis.
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
In the clinical practice guidelines for the care of girls and women with Turner syndrome, it was suggested that Turner syndrome diagnosis be considered when a phenotypical female presents with one or more typical clinical manifestations of Turner syndrome accompanied by a karyotype containing one X chromosome and complete or partial absence of the second sex chromosome.8 The consequence of the loss/partial loss of the X-chromosome is highly variable. The phenotype is unpredictable, and the signs of Turner syndrome are often overlooked, leading to a delay in diagnosis or not diagnosing it at all. In our population, the average age of diagnosis was 18.2 years, which is very late. In a recent article by Tuke et al.9 it was found that using single-nucleotide polymorphism array data on blood from the UK Biobank study (n = 245,000) in Great Britain identified many undiagnosed mosaic Turner syndrome patients as well as 30 non-diagnosed 45,X patients. This study reported a combined Turner syndrome prevalence of 88 per 100 000 females, confirming that this condition is not as rare as thought.
Beyond the amyloid hypothesis: how current research implicates autoimmunity in Alzheimer’s disease pathogenesis
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
Miyo K. Chatanaka, Dorsa Sohaei, Eleftherios P. Diamandis, Ioannis Prassas
The underlying causative factors that lead to autoimmunity remain elusive, and several hypotheses exist. Sex seems to play a pivotal role in autoimmunity risk. Women are more susceptible to autoimmune diseases by a factor of up to 16 [8]. This sexual dimorphism could be attributed to the sex chromosomes. Research suggests [9] that men with Klinefelter syndrome (genotype XXY) develop autoimmune diseases with the same frequency as women (genotype XX). Moreover, numerous genes on the X chromosome are related to immune function. Although one copy is usually deactivated, studies have shown that as many as 23% of X-linked genes escape this process, which could aggravate the immune response [10]. Interestingly, neurological disorders, such as Alzheimer’s disease (AD) and Multiple Sclerosis (MS) also display variable incidence according to sex [11]. Specifically, AD has a higher prevalence in women above 65 years old at a 1.6–3:1 ratio [12,13], and MS is more common in women by a ratio of 2–3:1 [14].
Clarifying the Blurry Boundaries between Research and Clinical Care
Published in The American Journal of Bioethics, 2022
Given the blurring of the lines between clinical care and research in the field of precision medicine, can the ACMG justify such a bright line? Other investigators support it. The Electronic Medical Records and Genomics (eMERGE) Network funded by the National Human Genome Research Institute (NHGRI) convened a return of results oversight committee to identify potentially returnable research results (NHGRI 2020). Fullerton and colleagues reported that the oversight committee was unanimous about the importance of returning chromosomal abnormalities in the clinical setting “even if the finding was incidental,” although there was wide variability in perspective in the research setting (Fullerton et al. 2012). Part of the reluctance is due to the context in which the findings are uncovered, the lack of relationship between researcher and participant, and the lack of resources (financial, appropriate counseling skills, and time) for appropriate follow-up in the research setting. The reluctance may be magnified by the fact that Klinefelter Syndrome is a sex chromosome abnormality. If the young man had been diagnosed in childhood, there would have been time to ensure that he received medical and psychosocial support and treatment in a developmentally appropriate way. What degree of responsibility are the researchers willing to assume to ensure that the disclosure is provided in such a way as to maximize benefits and minimize potential harms?