by Amanda H. Cardy, Linda Sharp, Nicola Torrance, Raoul C. Hennekam, Zosia Miedzybrodzka
Background Idiopathic congenital talipes equinovarus (CTEV) is a common developmental
foot disorder, the aetiology of which remains largely unknown. Some aspects
of the epidemiology suggest the possibility of aetiologically distinct
subgroups. Previous studies consider CTEV as a homogenous entity which may
conceal risk factors in particular subgroups. We investigate evidence for
aetiologically distinct subgroups of CTEV.
Methods Parents of 785 probands completed a postal questionnaire. Family pedigrees
were compiled by telephone. Case-only analysis was used to investigate
interactions between risk factors and sex of the proband, CTEV laterality
and CTEV family history.
Results The male:female ratio was 2.3:1, 58% of probands were
affected bilaterally and 11% had a first-second degree family
history. There were modest interactions between family history and twin
births (multivariate case - only odds ratio
[ORca]?=?3.87, 95%CI 1.19–12.62)
and family history and maternal use of folic acid supplements in early
pregnancy (ORca?=?0.62, 95%CI 0.38–1.01);
and between sex of the proband and maternal alcohol consumption during
pregnancy (female, positive history and alcohol consumed:
ORca?=?0.33, 95%CI 0.12–0.89). Previous
reports of an interaction between maternal smoking and family history were
not confirmed. Relatives of female probands were affected more often than
relatives of male probands.
Conclusions These results provide tentative evidence for aetiologically distinct CTEV
subgroups. They support the ‘Carter effect’, suggesting CTEV
develops though a multifactorial threshold model with females requiring a
higher risk factor ‘load’, and suggest areas where future
aetiological investigation might focus. Large multi-centre studies are
needed to further advance understanding of this common condition.
