Cleft-twin sets in Finland 1948-1987

Area of Science:

• Genetics
• Epidemiology
• Craniofacial Anomalies

Background:

• Clefts are common congenital anomalies with complex etiology.
• Twin studies are crucial for understanding the genetic and environmental contributions to clefts.
• Previous research suggests variations in cleft incidence and types across populations.

Purpose of the Study:

• To investigate the incidence, zygosity, concordance, and heritability of cleft lip and palate (CL(P)) and cleft palate (CP) in a Finnish twin cohort.
• To compare these findings with existing literature and Danish twin data.
• To explore potential differences in the genetic basis of CL(P) and CP in Finland.

Main Methods:

• Retrospective review of hospital records for Finnish patients with operated clefts born between 1948 and 1987.
• Inclusion of twin and triplet sibling data.
• Comparison with extensive literature review data and Danish cleft twin materials.
• Analysis of zygosity, concordance rates, and heritability indices for CL(P) and CP.

Main Results:

• The Finnish twin material comprised 105 twin sets and 3 triplet sets with clefts.
• A higher than expected rate of cleft palate (CP) was observed in Finnish twins (63%) compared to literature (23%) and Danish data (17%).
• Heritability for CP was higher in the Finnish cohort (49%) than in Danish (33%) or literature (36%) data, while CL(P) showed lower heritability (17%) in Finns compared to Danish (45%) and literature (43%).

Conclusions:

• The findings suggest a distinct genetic influence on clefting patterns in Finland, particularly a higher genetic component for cleft palate.
• The lower heritability of cleft lip and palate in Finland indicates a potentially greater role for non-genetic factors or unique genetic interactions.
• Differences in sex distribution and concordance rates further support population-specific etiological factors for CL(P) and CP.