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X chromosome constitution and the human female phenotype
Human Genetics
|January 1, 1980
Summary
Abnormal X chromosome constitutions in females can lead to various phenotypes through multiple pathways. Several hypotheses explain these correlations, with some being more probable than others.
Area of Science:
- Genetics
- Human Biology
- Developmental Biology
Background:
- The human female typically possesses two X chromosomes.
- Abnormalities in X chromosome number or structure can arise.
- These abnormalities are associated with diverse clinical phenotypes.
Purpose of the Study:
- To review correlations between abnormal X chromosome constitutions and phenotypes in human females.
- To discuss hypotheses explaining these correlations.
Main Methods:
- Literature review of studies on X chromosome abnormalities and phenotypes.
- Detailed discussion and evaluation of seven proposed hypotheses.
Main Results:
- Seven hypotheses were evaluated to explain X chromosome constitution-phenotype correlations.
- Hypotheses involving oocyte meiosis, active region counts, position effects, and competing inactivation patterns were deemed probable.
- Hypotheses regarding pre-inactivation damage, hemizygous expression, and irregular inactivation were less supported.
Conclusions:
- Phenotypic effects of X chromosome aberrations can occur through multiple simultaneous pathways.
- Specific hypotheses (2, 4, 5, 6) provide probable explanations for observed correlations.