Smoking, the xenobiotic pathway, and clubfoot

BACKGROUND

Isolated clubfoot is a common orthopedic birth defect that affects approximately 135,000 newborns worldwide. It is characterized by ankle equinus, hindfoot varus, and forefoot adductus. Although numerous studies suggest a multifactorial etiology, the specific genetic and environmental components have yet to be delineated. Maternal smoking during pregnancy is the only common environmental factor consistently shown to increase the risk for clubfoot. Moreover, a positive family history of clubfoot, in conjunction with maternal smoking, increases the risk 20-fold. These findings suggest that genetic variation in smoking metabolism (xenobiotic) genes may increase susceptibility to clubfoot. Based on this reasoning, we interrogated eight candidate genes from the xenobiotic metabolism.

METHODS

Twenty-two single-nucleotide polymorphisms and two null alleles in these genes (CYP1A1, CYP1A2, CYP1B1, CYP2A6, EPHX1, NAT2, GSTM1, and GSTT1) were genotyped in a dataset composed of non-Hispanic white and Hispanic multiplex and simplex families.

RESULTS

Only rs1048943/CYP1A1 had significantly altered transmission in the aggregate and multiplex non-Hispanic white datasets (p = 0.003 and p = 0.009, respectively). Perturbation of CYP1A1 can cause an increase in harmful, adduct-forming metabolic intermediates. A significant interaction between EPHX1 and NAT2 was also found (p = 0.007). Importantly, for CYP1A2, significant maternal (p = 0.03; relative risk [RR] = 1.24; 95% confidence interval [CI], 1.04-1.44) and fetal (p = 0.01; RR = 1.33; 95% CI, 1.13-1.54) genotypic effects were identified, suggesting that both maternal and fetal genotypes can negatively impact limb development. No association was found between maternal smoking status and variation in xenobiotic metabolism genes.

CONCLUSION

Together, these results suggest that xenobiotic metabolism genes are unlikely to play a major role in clubfoot; however, perturbation of this pathway may still play a contributory role.

Ponseti Brasil: a national program to eradicate neglected clubfoot - preliminary results

BACKGROUND

After hearing about the reproducible and excellent results of the Ponseti method for clubfoot treatment, a group of Brazilian orthopaedic surgeons organized and participated in a standardized national program to teach the Ponseti technique in 21 different cities across Brazil.

METHODS

A total of 21 Ponseti symposiums were organized in a standard fashion from January, 2007 to December, 2008. They consisted of a two-day program with lectures, hands-on cast application, and discussion of local clinical cases presented by orthopaedic surgeons. Thirteen Brazilian orthopaedic surgeons, who had been trained by the University of Iowa or centers recognized by them, taught the method. Financial support for travel was provided by an English charity: La Vida (Vital Investment for Developing Aid in Latin America). The physicians who attended the symposiums answered questionnaires before and after the training.

RESULTS

About 7% of the 8000 orthopaedic surgeons in Brazil (556 orthopaedic surgeons) were trained. These orthopaedic surgeons stated that they had treated about 4905 babies in the previous year via other methods, including extensive surgery. Seventeen percent of the surgeons did not know about the Ponseti technique at the start of the symposium. Eighty-eight percent reported they felt able to treat children with the Ponseti technique after the symposium. Ninety-four percent of respondents reported that the symposium changed their way of treating clubfoot

CONCLUSIONS

These Ponseti symposiums brought about an exchange of medical information and empowered the participants. This program is a good educational tool which can be used in eradicating neglected clubfoot in Brazil.

Diffusion of innovation: enhancing the dissemination of the Ponseti method in Latin America through virtual forums

This ethnographic study evaluated the use of low-bandwidth web-conferencing to enhance diffusion of a specific best practice, the Ponseti method to treat clubfoot, in three economically diverse countries in Latin America. A "Ponseti Virtual Forum" (PVF) was organized in Guatemala, Peru and Chile to examine the influences of economic level and telecommunication infrastructure on the effectiveness of tins approach. Across the three countries, a total of 14 different sites participated in the PVFs. Thirty-three Ponseti-trained practitioners were interviewed before and after each PVF, which included interactions with a Spanish-speaking Ponseti method expert. Semi-structured interviews, observations, and IP address data were triangulated and analyzed. The results demonstrated that 100% of the practitioners rated the sessions as very useful and that they would use this approach again. The largest obstacles to using PVFs were financial (7 out of 9 practitioners) in Guatemala; a lack of equipment and network access (6 out of 11) in Peru; and the organization and implementation of the conferences themselves (7 out of 9) in Chile. This study illustrates the usefulness of Ponseti Virtual Forums in Latin America. Health officials in Peru are currently developing a large-scale information session for traumatologists about the Ponseti method, while practitioners in Guatemala and Chile are organizing monthly scholarly meetings for physicians in remote areas. This initial feedback suggests that low-bandwidth web-conferencing can be an important vehicle for the dissemination of best practices, such as the Ponseti method, in developing countries.

The Ponseti method in Latin America: initial impact and barriers to its diffusion and implementation

The Ponseti method for correcting clubfoot is a safe, effective, and minimally invasive treatment that has recently been implemented in Latin America. This study evaluates the initial impact and unique barriers to the diffusion of the Ponseti method throughout this region. Structured interviews were conducted with 30 physicians practicing the Ponseti method in three socioeconomically diverse countries: Chile, Peru and Guatemala. Since learning the Ponseti method, these physicians have treated approximately 1,740 clubfoot patients, with an estimated 1,705 (98%) patients treated using the Ponseti method, and 35 (2%) patients treated using surgical techniques. The barriers were classified into the following themes: physician education, health care system of the country, culture and beliefs of patients, physical distance and transport, financial barriers for patients, and parental compliance with the method. The results yielded several common barriers throughout Latin America including lack of physician education, physical distance to the treatment centers, and financial barriers for patients. Information from this study can be used to inform, and to implement and evaluate specific strategies to improve the diffusion of the Ponseti method for treating clubfoot throughout Latin America.

Ponseti clubfoot management: changing surgical trends in Nigeria

BACKGROUND

Congenital clubfoot treatment continues to be controversial particularly in a resource-constrained country. Comparative evaluation of clubfoot surgery with Ponseti methods has not been reported in West Africa.

OBJECTIVES

To determine the effects of Ponseti techniques on clubfoot surgery frequency and patterns in Nigeria.

METHODS

This was a prospective hospital-based intention-to-treat comparative study of clubfoot managed with Ponseti methods (PCG) and extensive soft tissue surgery (NPCG). The first step was a nonselective double-blind randomization of clubfoot patients into two groups using Excel software in a university teaching hospital setting. The control group was the NPCG patients. The patients' parents gave informed consent, and the medical research and ethics board approved the study protocol. Biodata was gathered, clubfoot patterns were analyzed, Dimeglio-Bensahel scoring was done, the number of casts applied was tallied, and patterns of surgeries were documented. The cost of care, recurrence and outcomes were evaluated. Kruskal-Wallis analysis and Mann-Whitney U technique were used, and an alpha error of < 0.05 at a CI of 95% were taken to be significant.

RESULTS

We randomized 153 clubfeet (in 105 clubfoot patients) into two treatment groups. Fifty NPCG patients (36.2%) underwent manipulation and extensive soft tissue surgery and 55 PCG patients (39.9%) were treated with Ponseti methods. Fifty-two patients of the Ponseti group had no form of surgery (94.5% vs. 32%, p<0.000). Extensive soft tissue surgery was indicated in 17 (34.0%) of the NPCG group, representing 8.9% of the total of 191 major orthopaedic surgeries within the study period. Thirty-five patients (70.0%) from the NPCG group required more than six casts compared to thirteen patients (23.6%) of the PCG (p<0.000). The mean care cost was high within the NPCG when compared to the Ponseti group (48% vs. 14.5%, p<0.000). The Ponseti-treated group had fewer treatment complications (p<0.003), a lower recurrence rate (p<0.000) and satisfactory early outcome (p<0.000).

CONCLUSION

Major clubfoot surgery was not commonly indicated among patients treated with the Ponseti method. The Ponseti clubfoot technique has reduced total care costs, cast utilization, clubfoot surgery frequency and has also changed the patterns of surgery performed for clubfoot in Nigeria.

From cutting to casting: impact and initial barriers to the Ponseti method of clubfoot treatment in China

In 2005, a nationwide clubfoot treatment program focused on the Ponseti method -an effective, affordable and minimally-invasive method- was initiated in China. The purpose of this study was to evaluate and identify barriers to the program. A qualitative study (rapid ethnographic study) was conducted using semi-structured interviews of 44 physicians who attended four of the 10 Ponseti training workshops, focus groups with parents of children with clubfoot, and observation. Several barriers to the Ponseti method are quite unique due to China's size, socio-economics, culture, politics, and healthcare systems. The barriers were classified into seven themes: (i) physician education, (ii) caregiver compliance, (iii) culture, (iv) public awareness, (v) poverty, (vi) financial constraints for physicians/hospitals, and (vii) challenges of the treatment process. A number of suggestions that could be helpful in reducing or eliminating the effects of these barriers were also identified: (i) pamphlets explaining clubfoot and treatment for caregivers, (ii) directories of Ponseti providers, (iii) funding/financial support, and (iv) improving public awareness. The information from this study provides healthcare planners with knowledge to assist in meeting the needs of the population and continued implementation of effective and culturally appropriate awareness and treatment programs for clubfoot throughout China.

Apoptotic gene analysis in idiopathic talipes equinovarus (clubfoot)

Idiopathic talipes equinovarus, also known as clubfoot, is a common birth defect occurring in one of 1000 live births. It is a complex disorder in which multiple genes and environmental factors may play an etiologic role. Several chromosomal deletion regions, including 2q31-33, are associated with talipes equinovarus and may harbor genes that contribute to the idiopathic talipes equinovarus phenotype. Previously, two STRs in the 2q31-33, GATA149B10 and D2S1371, showed linkage with association to idiopathic talipes equinovarus. Single nucleotide polymorphisms (SNPs) in three apoptotic genes (Casp8, Casp10, and CFLAR) near GATA149B10 were genotyped in idiopathic talipes equinovarus families. rs3731714 in Casp10 showed linkage with association, suggesting variation in the apoptotic gene pathway, which is important in limb morphogenesis, and may play a role in the development of idiopathic talipes equinovarus. We genotyped SNPs spanning seven apoptotic genes-Casp3, Casp8, Casp9, Casp10, Bid, Bcl-2 and Apaf1-in 210 simplex trios and 139 multiplex families and tested for link-age and association to idiopathic talipes equinovarus. One SNP in each of the genes provided suggestive evidence of association with idiopathic talipes equinovarus. Several haplotypes constructed from these SNPs displayed altered transmission. These data suggest genetic variation in apoptotic genes may play a role in development of idiopathic talipes equinovarus.

Increasing incidence of club foot with higher population density: incidence and geographical variation in Denmark over a 16-year period--an epidemiological study of 936,525 births

BACKGROUND

The occurrence of club foot (CF) varies between countries and populations, and may be related to endogenous and exogenous factors. We analyzed the occurrence of CF in a whole country over a long period of time (16 years).

METHODS

Patients born in Denmark with a foot deformity 1978-93 were identified from the National Patient Register and the Register of Inborn Malformations. The records for each patient were studied in the hospital departments to establish the diagnoses and to obtain additional information. Demographic data were obtained from the Danish National Demographical Institute and from the Danish Population Register.

RESULTS

The incidence of isolated CF was 1.2/1,000 live births. It increased significantly during the study period, and the incidence of CF and the standardized morbidity ratio for CF were significantly positively correlated to population densities in the counties and the districts. There was no significant increase in the relative proportion of children with CF born to non-Scandinavian parents during the period.

INTERPRETATION

The increasing incidence of isolated CF with higher population density indicates that there may be exogenous factors that are pathogenic.

Risk factors for isolated talipes equinovarus in Western Australia, 1980-1994

A case-control study based on routinely collected data for a West Australian (WA) cohort of births born 1980-94 inclusive was used to identify potential risk factors for the foot deformity isolated talipes equinovarus. Race and sex were identified as risk factors and risk modifiers of the condition in WA infants. In comparison with their female counterparts, Aboriginal males were at greater risk of the deformity than Caucasian males (odd ratio [OR] 7.15, 95% confidence interval [CI] 2.68, 21.12 vs. OR 1.63, 95% CI 1.24, 2.15 respectively). Sex-specific risk estimates of the deformity showed that Aboriginal males were at more than four times the risk of Caucasian males (OR 4.27, 95% CI 2.30, 8.25 respectively), but the risk amongst Aboriginal females was not dissimilar to the risk amongst Caucasian females (OR 1.12, 95% CI 0.49, 2.45). Intrauterine constraint of the fetus was not found to be an important contributing factor to the deformity after accounting for the effect of all risk factors modelled in multivariable analyses. Indicators of intrauterine constraint including prolonged gestation, high infant birthweight, young maternal age (< 20 years) and breech presentation were not associated with excess numbers of isolated talipes equinovarus cases. Limited numbers of cases associated with other indicators of intrauterine constraint, including the specific categories of short maternal stature and a twin pregnancy prevented definitive conclusions regarding their association with the deformity. Improved data quality for gestational age estimates and oligohydramnios status are required before determining the prenatal risk impact of season of conception and of reduced amniotic fluid levels, respectively, on the occurrence of the deformity.

Genetics of club foot in Maori and Pacific people

The role of major gene and multifactorial inheritance in the aetiology of club foot in the New Zealand Polynesian population was studied using 287 New Zealand Maori and Pacific club foot families. The club foot family data were analysed by complex segregation analysis under the mixed model using the computer program POINTER. This analysis shows that the best genetic model for club foot in this population is a single dominant gene with a penetrance of 33% and a predicted gene frequency of 0.9%. These data provide a scientific foundation for molecular studies in the Maori and Polynesian population to identify putative club foot genes.

Segregation analysis of idiopathic talipes equinovarus in a Texan population

"Idiopathic" talipes equinovarus (ITEV) is a nonsyndromal congenital anomaly of one or both feet. Casting and surgery are often necessary to obtain correct foot alignment. In spite of treatment, residual deformities of the feet occur and calf muscles may be hypoplastic. The cause of ITEV is unknown but genetic factors have been postulated. Complex segregation analysis was performed on 173 ITEV families including 93 Caucasian and 48 Hispanic families. The recessive mixed model was the best fitting model and no differences were found based on ethnicity. These results confirm previous studies suggesting that there is a genetic component to the development of ITEV.

Congenital talipes in Malaysian neonates: incidence, pattern and associated factors

A study was carried out on 8,369 neonates delivered in the Maternity Hospital, Kuala Lumpur over a period of four months. Forty-nine neonates (5.6 per 1000 livebirths) had congenital talipes. The incidence of congenital talipes equinovarus (CTEV) was 4.5 per 1000 livebirths while that of congenital talipes calcaneovalgus (CTCV) was 1.3 per 1000 livebirths. 6/11 (54.5%) of the CTCV was unilateral, the ratio of right to left feet involvement being 1:1. Only 12/38 (31.5%) of the CTEV were unilateral, the ratio of right to left feet involvement being 1:2. Congenital talipes was significantly more common in the low birthweight neonates (p less than 0.001). However, the condition was not significantly more common in neonates with breech presentation nor in those born to primigravida mothers. Our data suggested that multifactorial genetic background as the most likely underlying cause of congenital talipes in Malaysian neonates.