(The following abstract from the November 1964 issue of Birth Defects is reprinted with the permission of the National Foundation - March of Dimes.)
Family Studies And The Cause Of Congenital Club Foot. Talipes Equinovarus, Talipes Calcaneo-Valgus And Metatarsus Varus.
J. Bone Joint Surg. (Brit.) 46(3):445-463, August 1964.
Wynne-Davies, R. (Princess Elizabeth Orthopaedic Hospital, Exeter, England).
A statistical assay of 635 congenital club foot patients in a stable population is tabulated.
The male to female ratio is 2.17:1 for talipes equinovarus (TE), with a total incidence of 1.24 per 1000 live births. Almost 37, of relevant sibs also have the same defect relative to 1.2%, per 1000 of the general population; or a 20-fold risk for a second child, given one proband. There is also increased risk for male relatives of the female patient, while female relatives of a male patient are little susceptible. Consanguinity was not involved and parental age and birth order were not factors, although the paternal-maternal age difference was slightly wider than the national average. No easily recognizable pattern is available, but --based on independent identical twin studies -- environmental factors must be implicated. The risk for anyone is 1:800.
The sex ratio for talipes calcaneo-valgus (TCV) and metatarsus (MV) are 0.61:1 and 0.76:1, respectively, with 4.5% of all sibs affected in contrast to one per 1000 in the population. TCV was especially frequent in first born children of younger mothers, but neither variable was significant for MV. Parental age differences were not factors. The risk for any person is 1:1000. No unequivocal inheritance pattern is known, but the TCV prevalence in first-borns suggests environmental compression.
Minor connective tissue defects, including joint laxity, hernia, recurrent patellar dislocation, and flexion contractures, among others, were found at least once in 17% to 18% of all TE and TCV, but not MV, patients. Peripheral deformities, including ring constrictions, syndactyle, and absent or extra fingers, among others, were also found in 4% to 5% of all cases. The tendency toward soft tissue disorder was noted in up to 2% of the parents and sibs of all probands. This combined skeletal soft tissue defect suggests a genetic error in connective tissue formation leading to mobile feet abnormally sensitive to intrauterine stress. Equinovarus would be the outcome of such early fetal fixation. A later fetal stress might then be responsible for the easily corrigible "postural" TE, which is known to involve more females than males. Connective tissue dysfunction in these patients responds no less to treatment than that in otherwise normal persons and is no more severe when more than one family member is affected. (18 references).