Related Experiment Video
Updated: May 15, 2026
12:47
Spectral Karyotyping to Study Chromosome Abnormalities in Humans and Mice with Polycystic Kidney Disease
Published on: February 3, 2012
Digit ratio (2D:4D) in Klinefelter's syndrome
J T Manning1, L P Kilduff, R Trivers
1Department of Psychology, Swansea University, Swansea, UK. j.manning@swansea.ac.uk
Andrology
|December 22, 2012
Summary
Klinefelter syndrome (KS) males exhibit higher second to fourth digit ratios (2D:4D), similar to female norms, indicating altered prenatal testosterone exposure. Testosterone supplementation may be more common in KS males with lower 2D:4D.
Area of Science:
- Endocrinology
- Human Biology
- Genetics
Background:
- The second to fourth digit ratio (2D:4D) is a recognized marker for prenatal testosterone exposure.
- Klinefelter syndrome (KS; 47 XXY) is characterized by endocrine abnormalities, including reduced testosterone levels throughout life.
Purpose of the Study:
- To investigate the 2D:4D digit ratio patterns in males with Klinefelter syndrome.
- To compare 2D:4D ratios in KS males with their relatives and a control group.
- To explore the relationship between 2D:4D and testosterone supplementation in KS males.
Main Methods:
- Digit lengths (2D and 4D) were measured in 51 KS males, 31 relatives, and 306 controls.
- Anthropometric measurements (height) were compared between groups.
- Statistical analyses were performed to compare 2D:4D ratios and explore correlations with testosterone prescription.
Main Results:
- KS males were taller than their fathers and had shorter fingers relative to height compared to fathers, male controls, and mothers.
- KS males exhibited significantly higher 2D:4D ratios on both hands compared to fathers and on the right hand compared to mothers.
- Higher right 2D:4D and right-left 2D:4D differences were observed in KS males not prescribed testosterone compared to those prescribed.
Conclusions:
- Klinefelter syndrome males display 2D:4D digit ratio patterns typically seen in females, suggesting distinct prenatal androgenic environments.
- These findings highlight potential differences in androgen sensitivity or exposure in KS.
- Testosterone supplementation in KS males appears more frequently prescribed for individuals with lower 2D:4D ratios.
Related Concept Videos
02:45The Ratio of X Chromosome to Autosomes
In most organisms, sex is determined by the ratio of X and Y chromosomes. However, in some organisms, such as Drosophila and C.elegans, sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. The Y chromosome in Drosophila is active but does not determine sex. It contains genes responsible for the production of sperms in adult flies.
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
01:17Karyotyping
Overview
01:17Karyotyping
Overview
01:21Nondisjunction
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers. Nondisjunction is common during anaphase I or anaphase II of meiosis. Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold sister...
01:29Nondisjunction
During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.
01:29Nondisjunction
During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.