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Cleft lip (+/- cleft palate) in Danish twins, 1970-1990
K Christensen1, P Fogh-Andersen
1Genetic Epidemiologic Research Unit, Odense University, Denmark.
American Journal of Medical Genetics
|November 1, 1993
Summary
Genetic factors significantly contribute to cleft lip and palate (CL(P)) development, as indicated by twin study concordance rates. Environmental and stochastic factors also play a role in CL(P) etiology.
Area of Science:
- Genetics
- Developmental Biology
- Epidemiology
Background:
- Cleft lip with or without cleft palate (CL(P)) etiology remains incompletely understood.
- Classical twin studies are crucial for disentangling genetic and environmental influences.
- Combining twin concordance with familial risk data can elucidate inheritance patterns.
Purpose of the Study:
- To investigate the genetic and environmental contributions to non-syndromic CL(P) using a Danish twin registry.
- To estimate CL(P) concordance rates in monozygotic and dizygotic twins.
- To refine understanding of CL(P) inheritance patterns.
Main Methods:
- Utilized three nationwide Danish ascertainment sources (1970-1990), primarily Danish surgical files.
- Identified 39 twin pairs with non-syndromic CL(P).
- Determined zygosity using blood, serum, enzyme typing, and sex discordance (in >70% of cases).
Main Results:
- Observed higher than expected numbers of monozygotic and dizygotic twin CL(P) cases, though not statistically significant.
- Proband concordance rate for CL(P) was 60% in monozygotic twins and 10% in dizygotic twins.
- Familial recurrence patterns, interpreted with new concordance estimates, suggest no single locus explains >6-fold increase in first-degree relative risk.
Conclusions:
- Genetic factors play a substantial role in the etiology of CL(P).
- Environmental and/or stochastic factors are also implicated in CL(P) development.
- The inheritance of CL(P) is likely complex, involving multiple genetic and environmental interactions.