Chromosomal Variants Amongst XXY (Klinefelter Syndrome)

A. Frühmesser D. Kotzot
Division for Human Genetics, Department for Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck , Austria

Klinefelter syndrome (XXY) describes the phenotype of the most common sex chromosome abnormality in humans and occurs in one of every 600 newborn males. The typical symptoms are a tall stature, narrow shoulders, broad hips,sparse body hair,gynecomastia, small testes, absent spermatogenesis, normal to moderately reduced Leydig cell function, increased secretion of follicle-stimulating hormone, androgen deficiency, and normal to slightly decreased verbal intelligence.

Is the prevalence of Klinefelter syndrome increasing?

Joan K Morris, Eva Alberman, Claire Scott and Patricia Jacobs

The birth prevalence of sex chromosome trisomies (SCT), that is individuals with an XYY, XXY or XXX sex chromosome constitution, is traditionally based on six surveys of unselected newborns carried out in the 1960s and early 1970s. All three SCTs had a prevalence of 1 in 1000 same-sex births. We re-examined these prevalences based on additional cytogenetic studies of newborn surveys, spontaneous abortions, perinatal deaths and prenatal diagnoses.

Recent Advances in Managing and Understanding Klinefelter Syndrome

As a genetic condition that affects 1 in 600 live male births, KS is being seen commonly enough that it is important for practitioners to understand the wide spectrum of issues and the multidisciplinary approach that is required to appropriately treat these patients.It is also essential to take note of distinct features that are known to be associated with KS, as this allows providers the opportunity to recognize undiagnosed cases. Along these lines, there is increasing momentum in genomic studies that are beginning to shed light on the differential gene expression that may explain the KS phenotypes and the variability within.

Mortality in Patients with Klinefelter Syndrome in Britain: A Cohort Study

47XXY also known as Klinefelter’s Syndrome is a numerical chromosome variation, characterised by the presence of one or more extra X chromosomes. It occurs in about 1.5 per 1000 of the male population. The clinical syndrome was initially described in 1942, and the chromosome constitution was discovered in 1959.

Guidance on the Assessment and Diagnosis of Intellectual Disabilities in Adulthood


This document has been produced as guidance for clinical psychologists who are
frequently asked to assess whether or not an individual has an intellectual disability. It will also be of use to commissioners, colleagues in intellectual disability services and families and individuals who are seeking clarification on this issue.

Beyond the Literal Meaning of Words in Children Who Are XXY

Abstract: Literature on children with Klinefelter Syndrome (KS) points to general linguistic difficulties in both comprehension and production among other cognitive functions, and in the majority of cases, these coexist with an intellectual level within the norms. In these conditions, children having language delay generally engage in language therapy and are systematically monitored across ages.

What Is the Biologic Basis of Variations in Sexual Phenotype

The description of the human genome structure only 20 years ago has accelerated our ability to understand the genetic components of human sexuality and to assess their interaction with hormones in the establishment of phenotypic sex. The view that the world’s population can be separated into a clearly defined dyadic unit of male and female is defunct; not only clinical observations but molecular biology has established that sexual identity is on a continuum, with an enormous potential for variance.

The Role of Hypogonadism in Klinefelter Syndrome

At birth some KS boys may show signs of intrauterine hypogonadism such as micropenis or cryptorchism and although anecdotal, testosterone injections may alleviate this problem. Conflicting data regarding the surge in testosterone (mini-puberty) during the first 3 months has been published; demonstrating either low levels of testosterone,high-normal levels of testosterone or low-normal testosterone.