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Genetic epidemiology of twinning: a population-based study
American Journal of Medical Genetics
|January 1, 1985
Summary
Mothers of twins show higher kinship and lower inbreeding, suggesting a genetic basis for twinning. This genetic factor may involve dominant gene expression, influencing twin types and maternal age.
Area of Science:
- Human genetics
- Reproductive biology
- Population genetics
Background:
- Twinning can occur as like-sex or unlike-sex pairs.
- The genetic and environmental factors influencing twinning are not fully understood.
- Previous studies suggest a maternal genetic influence on twinning rates.
Purpose of the Study:
- To investigate the genetic kinship and inbreeding patterns in mothers of twins.
- To explore potential genetic predispositions for twinning.
- To examine how maternal age and twin type relate to genetic factors.
Main Methods:
- A pair-matched case-control study design was employed.
- Kinship analysis was conducted on mothers of twins and their ancestors.
- Inbreeding coefficients were calculated for cases and controls.
Main Results:
- Mothers of twins exhibited higher kinship compared to control individuals.
- Study cases demonstrated lower inbreeding levels than control subjects.
- Higher kinship was observed in mothers of unlike-sex twins (born after age 30) and, to a lesser extent, like-sex twins (born younger than 30).
Conclusions:
- The findings suggest a genetic origin for both like-sex and unlike-sex twins.
- A widespread gene with dominant or co-dominant expression may play a role in twinning.
- Genetic factors, potentially influenced by maternal age, contribute to twinning occurrence.