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Genetics of sexual development: a new paradigm
Stan R Blecher1, Robert P Erickson
1Department of Molecular Biology and Genetics (Emeritus), University of Guelph, Guelph, Ontario, Canada.
American Journal of Medical Genetics. Part A
|November 15, 2007
Summary
Sexual development involves more than just gonads. New research suggests sexual dimorphism begins before gonadal development, challenging the traditional "default female" model and highlighting complex genetic pathways in human sex determination.
Area of Science:
- Developmental Biology
- Genetics
- Human Physiology
Background:
- The classical model of sexual development posits that sex determination is solely gonad-dependent.
- This paradigm suggests female development is the default pathway in the absence of male factors.
Purpose of the Study:
- To propose a new paradigm for human and mammalian sexual development.
- To incorporate recent findings that challenge the classical model.
Main Methods:
- Review of current research and genetic findings in sexual development.
- Analysis of the interplay between sex chromosomes, autosomal genes, and hormonal signaling.
Main Results:
- Sexual dimorphism precedes gonadal development (Pregonadal Stage).
- Both male (Y-linked SRY) and female (X-linked) primary sex-determining mechanisms likely exist.
- Proximate gonad determination involves autosomal genes, with complex pathways from primary factors.
- Secondary sexual differentiation is not a default process but requires ovarian hormones.
Conclusions:
- The classical paradigm of sexual development is incomplete.
- A new model is proposed where sexual dimorphism is pre-gonadal and female development is actively regulated.
- Sex-determining genes influence both gonadal and non-gonadal organ development.
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