Developmental and family history-based analysis of congenital fused labia phenotype in the captive common marmoset (Callithrix jacchus).

BACKGROUND: Congenital fused labia (CFL) is defined as a failure or significant delay in the opening of the juvenile sealed labia majora. This phenotype is known to be variably common in adult captive female marmosets but has never been investigated in detail before. MATERIALS AND METHODS: Here, we define, describe and quantify the variations in the degree of closure of the vulva in 122 captive marmosets (Callithrix jacchus) from 1.2 to 42 months old and include colony analysis. RESULTS: There was a negative correlation between the degree of labial fusion and animal age after prepubertal period (P < 0.05). CFL females had higher number CFL relatives (4.3 ± 0.6 vs 2.4 ± 0.5 for non-CFL, P < 0.05) and more external ancestors compared to non-CFL (P < 0.05). CONCLUSIONS: Our results therefore suggest that CFL phenotype is most likely associated with epigenetic effects induced by the captive environment and colony management strategy of extensive crossing of family lines to promote heterozygosity.