Smoking, the xenobiotic pathway, and clubfoot

Prenatal diagnosis and genetic etiology analysis of talipes equinovarus by chromosomal microarray analysis

BACKGROUND

With the advancement of molecular technology, fetal talipes equinovarus (TE) is believed to be not only associated with chromosome aneuploidy, but also related to chromosomal microdeletion and microduplication. The study aimed to explore the molecular etiology of fetal TE and provide more information for the clinical screening and genetic counseling of TE by Chromosomal Microarray Analysis (CMA).

METHODS

This retrospectively study included 131 fetuses with TE identified by ultrasonography. Conventional karyotyping and SNP array analysis were performed for all the subjects. They were divided into isolated TE group (n = 55) and complex group (n = 76) according to structural anomalies.

RESULTS

Among the total of 131 fetuses, karyotype analysis found 12(9.2%) abnormal results, while SNP array found 27 (20.6%) cases. Trisomy 18 was detected most frequently among abnormal karyotypes. The detection rate of SNP array was significantly higher than that of traditional chromosome karyotype analysis (P < 0.05). SNP array detected 15 (11.5%) cases of submicroscopic abnormalities that karyotype analysis did not find. The most common CNV was the 22q11.2 microdeletion. For both analyses, the overall detection rates were significantly higher in the complex TE group than in the isolated TE group (karyotype: P < 0.05; SNP array: P < 0.05). The incremental yield of chromosomal abnormalities in fetuses with unilateral TE (22.0%) was higher than in fetuses with bilateral TE (19.8%), but this difference was not statistically significant (P > 0.05). Abnormal chromosomes were most frequently detected in fetuses with TE plus cardiovascular system abnormalities.

CONCLUSION

Fetal TE is related to chromosomal microdeletion or microduplication. Prenatal diagnosis is recommended for fetuses with TE, and CMA testing is preferred. CMA can improve the detection rate of chromosomal abnormalities associated with fetal TE, especially in pregnancies with complex TE.

Genotype-phenotype correlation in clubfoot (talipes equinovarus)

Clubfoot (talipes equinovarus) is a congenital malformation affecting muscles, bones, connective tissue and vascular or neurological structures in limbs. It has a complex aetiology, both genetic and environmental. To date, the most important findings in clubfoot genetics involve PITX1 variants, which were linked to clubfoot phenotype in mice and humans. Additionally, copy number variations encompassing TBX4 or single nucleotide variants in HOXC11, the molecular targets of the PITX1 transcription factor, were linked to the clubfoot phenotype. In general, genes of cytoskeleton and muscle contractile apparatus, as well as components of the extracellular matrix and connective tissue, are frequently linked with clubfoot aetiology. Last but not least, an equally important element, that brings us closer to a better understanding of the clubfoot genotype/phenotype correlation, are studies on the two known animal models of clubfoot-the pma or EphA4 mice. This review will summarise the current state of knowledge of the molecular basis of this congenital malformation.

Associations and interaction effects of maternal smoking and genetic polymorphisms of cytochrome P450 genes with risk of congenital heart disease in offspring: A case-control study

To assess associations and interactions of maternal smoking and cytochrome P450 (CYP450) genetic variants with the developments of congenital heart disease (CHD) and specific subtypes.A case-control study of 654 cases and 666 controls was conducted from November 2017 to March 2020. The exposures of interest were maternal active and passive smoking before/in the early pregnancy and CYP450 genetic polymorphisms. Data were analyzed using the Chi-square test and logistic regression analysis.After adjusting for the potential confounding factors, our study showed maternal active (ORadj = 2.34, 95%CI: 1.19-4.60) or passive (ORadj = 1.76, 95%CI: 1.34-2.31) smoking before pregnancy, passive smoking in the early pregnancy (ORadj = 3.05, 95%CI: 2.26-4.12), as well as polymorphisms of CYP450 at rs1065852 (G/A vs G/G: ORadj = 1.46, 95%CI: 1.07-1.99; A/A vs G/G: ORadj = 1.63, 95%CI: 1.15-2.33) and rs16947 (A/A vs G/G: ORadj = 3.61, 95%CI: 2.09-6.23), were significantly associated with risk of total CHD in offspring. Similar results were also found for some subtypes of CHD. Additionally, significant interactions between maternal smoking and CYP450 genes on the risk of CHD were observed.Maternal smoking and CYP450 genetic variants were associated with increased risk of CHD and specific subtypes in offspring. And the effects of CYP450 genes on CHD may be modified by maternal smoking.

HOXA9 rs3801776 G>A polymorphism increases congenital talipes equinovarus risk in a Chinese population

BACKGROUND

Congenital talipes equinovarus (CTEV) is the most common congenital deformity in children, and muscular dysplasia plays a potential role in the etiology of CTEV. Notably, previous studies have found that HOXA9 rs3801776 and TPM2 rs2025126 genetic polymorphisms play important roles in regulating muscle development in Caucasian children; however, there is a lack of investigations conducted in Chinese children.

METHODS

We conducted a hospital-based, case-control study of 189 children with CTEV and 457 CTEV-free children aiming to examine the associations between these two polymorphisms and CTEV susceptibility. The rs3801776 (G>A) and rs2025126 (G>A) polymorphisms were genotyped using TaqMan. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to measure the associations between the selected polymorphisms and CTEV susceptibility.

RESULTS

We found that rs3801776A was associated with increased CTEV risk (GA versus GG: adjusted OR = 1.81, 95% CI = 1.22-2.69, p = 0.0031; AA versus GG: adjusted OR = 2.19, 95% CI = 1.28-3.73, p = 0.0041; GA/AA versus GG: adjusted OR = 1.89, 95% CI = 1.29-2.76, p = 0.0010). In a stratified analysis, the risk effect of rs3801776 GA/AA was observed in both unilateral and bilateral patients.

CONCLUSIONS

The present study suggests that the rs3801776 G>A polymorphism is associated with CTEV risk in Chinese children; however, this conclusion should be validated in larger studies.

Risk of congenital heart diseases associated with NAT2 genetic polymorphisms and maternal polycyclic aromatic hydrocarbons exposure

OBJECTIVE

N-Acetyltransferase 2 (NAT2) is a phase II xenobiotic-metabolizing enzyme participating in the detoxification of toxic arylamines and aromatic amines. The present study was designed to investigate whether maternal NAT2 genetic polymorphisms are associated with fetal susceptibility to congenital heart diseases (CHDs) and to assess whether the risk is modified by polycyclic aromatic hydrocarbons (PAHs) exposure.

METHODS

We conducted a hospital-based case-control study to investigate the association of NAT2 gene polymorphisms (rs1799930 G/A, rs1208 A/G, and rs1799931 G/A) and the combinations of PAHs exposure and genetic variants with the risk of CHDs. Three hundred fifty-seven mothers of CHDs fetuses and 270 control mothers were recruited. Logistic regression models for the risk of CHDs were applied to determine the effect of NAT2 polymorphisms, as well as gene-exposure interactions.

RESULTS

Our study did not demonstrate an association of maternal NAT2 genetic polymorphisms alone with CHDs occurrence. However, we found that certain genetic polymorphisms of NAT2 in the present of high PAHs exposure have a higher risk of CHDs.

CONCLUSION

Our study suggests that the risk of CHDs associated with maternal NAT2 gene polymorphisms is potentiated by PAHs exposure.

The genetics of isolated and syndromic clubfoot

PURPOSE

Congenital clubfoot is a serious birth defect that affects nearly 0.1% of all births. Though there is strong evidence for a genetic basis of isolated clubfoot, aside from a handful of associations, much of the heritability remains unexplained.

METHODS

By systematically examining the genes involved in syndromic clubfoot, we may find new candidate genes and pathways to investigate in isolated clubfoot.

RESULTS

In addition to the expected enrichment of extracellular matrix and transforming growth factor beta (TGF-β) signalling genes, we find many genes involved in syndromic clubfoot encode peroxisomal matrix proteins, as well as enzymes necessary for sulfation of proteoglycans, an important part of connective tissue. Further, the association of Filamin B with isolated clubfoot as well as syndromic clubfoot is an encouraging finding.

CONCLUSION

We should examine these categories for enrichment in isolated clubfoot patients to increase our understanding of the underlying biology and pathophysiology of this deformity. Understanding the spectrum of syndromes that have clubfoot as a feature enables a better understanding of the underlying pathophysiology of the disorder and directs future genetic screening efforts toward certain genes and genetic pathways.

LEVEL OF EVIDENCE

V.

Association of breast cancer risk with polymorphisms in genes involved in the metabolism of xenobiotics and interaction with tobacco smoking: A gene-set analysis

Single nucleotide polymorphisms (SNPs) in genes involved in xenobiotics metabolism (XM) are suspected to play a role in breast cancer risk. However, previous findings based on a SNP by SNP approach need to be replicated taking into account the combined effects of multiple SNPs. We used a gene-set analysis method to study the association between breast cancer risk and genetic variation in XM genes (seen as a set of SNPs) and in the XM pathway (seen as a set of genes). We also studied the interaction between variants in XM genes and tobacco smoking. The analysis was conducted in a case-control study of 1,125 cases and 1,172 controls. Using a dedicated chip, genotyping data of 585 SNPs in 68 XM genes were available. Genetic variation in the whole XM pathway was significantly associated with premenopausal breast cancer risk (p = 0.008). This association was mainly driven by genetic variation in NAT2, CYP2C18, CYP2C19, AKR1C2 and ALDH1A3. The association between the XM gene pathway and breast cancer was observed among current and previous smokers, but not among never smokers (p = 0.013 for interaction between XM genes and tobacco smoking status). The association with breast cancer risk indicates that XM genes variants may play a role in breast carcinogenesis through their detoxification function of environmental pollutants, such as those contained in tobacco smoke.

Genetic variation affects congenital heart defect susceptibility in offspring exposed to maternal tobacco use

BACKGROUND

Congenital heart defects (CHDs) are among the most prevalent and serious birth defects, occurring in 8 to 10 of every 1000 live births in the United States. Epidemiologic studies have reported an association between CHDs and maternal smoking, but it remains unknown how genes impact the susceptibility of offspring to CHDs in the presence of maternal tobacco use.

METHODS

Using data from 403 case- and 219 control-parental triads enrolled in the National Birth Defects Prevention Study between 1998 and 2008, we investigated the association between CHDs and maternal and infant genetic variants involved in the tobacco metabolism and DNA repair pathways among mothers who smoked prenatally.

RESULTS

The maternal genotypes of single nucleotide polymorphisms in the excision repair cross-complementation group 1 (ERCC1), poly (ADP-ribose) polymerase 2 (PARP2), and ERCC5 genes were identified to be significantly associated with the occurrence of CHDs in the presence of maternal tobacco use. Our analysis also revealed a moderate association between the infant genotypes of polymorphisms in the O-sialoglycoprotein endopeptidase (OSGEP) gene and increased risk of CHDs among mothers who smoked.

CONCLUSION

Our study provides evidence that maternal and infant polymorphisms within the ERCC1, PARP2, ERCC5, and OSGEP genes are associated with CHD risk in the presence of maternal tobacco use. These results may provide insight into the susceptibility of having a pregnancy affected by CHDs among women who smoke.

A glimpse into Texas Scottish Rite Hospital's educational, clinical care, and research development

This article describes four areas of pediatric orthopaedic education, research, and clinical care undertaken at Texas Scottish Rite Hospital (TSRH) over the past 25 years. These areas include the weekly preoperative conferences, the evolution of the limb lengthening and deformity correction program, the development of the TSRH instrumentation system, and the evolution of the clubfoot treatment program.

Etiopathogenesis of equinovarus foot malformations

Congenital talipes equinovarus (CTEV) is the most common musculoskeletal birth defect affecting approximately 1/700-1/1000 of liveborns. Even though extensive epidemiological and genetic studies have been carried out to address its causes, the precise mechanisms leading to this common birth defect remain elusive. CTEV is a multifactorial disorder, hence the combination of genetic and environmental factors are known contributors to this developmental abnormality. So far a handful of genes involved in limb patterning like PITX1, HOXA, HOXD, TBX4, and RBM10, as well as genes involved in muscle contraction, have been identified as possible players. Among many environmental factors investigated, maternal smoking seems to hold the strongest consistent association with this disorder. This article will review and discuss some of the most common genetic and environmental factors associated with the etiopathogenesis of CTEV.

Maternal smoking, xenobiotic metabolizing enzyme gene variants, and gastroschisis risk

Maternal smoking during pregnancy is one proposed risk factor for gastroschisis, but reported associations have been modest, suggesting that differences in genetic susceptibility might play a role. We included 108 non-Hispanic white and 62 Hispanic families who had infants with gastroschisis, and 1,147 non-Hispanic white and 337 Hispanic families who had liveborn infants with no major structural birth defects (controls) in these analyses. DNA was extracted from buccal cells collected from infants and mothers, and information on periconceptional smoking history was obtained from maternal interviews, as part of the National Birth Defects Prevention Study. We analyzed five polymorphisms in three genes that code for enzymes involved in metabolism of some cigarette smoke constituents (CYP1A1, CYP1A2, and NAT2). Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) independently for maternal smoking and maternal and infant gene variants, and to assess joint associations of maternal smoking and maternal or infant gene variants with gastroschisis. In analyses adjusted for maternal age at delivery and stratified by maternal race-ethnicity, we identified three suggestive associations among 30 potential associations with sufficient numbers to calculate ORs: CYP1A1*2A for non-Hispanic white mothers who smoked periconceptionally (aOR = 0.38, 95% CI 0.15-0.98), and NAT2*6 for Hispanic non-smoking mothers (aOR = 2.17, 95% CI 1.12-4.19) and their infants (aOR = 2.11, 95% CI 1.00-4.48). This analysis does not support the occurrence of effect modification between periconceptional maternal smoking and most of the xenobiotic metabolizing enzyme gene variants assessed.

Descriptive epidemiology of clubfoot in Peru: a clinic-based study

congenital clubfoot is the most common birth defect of the musculoskeletal system and affects 1 in every 1000 live births each year.(1) Although there have been numerous studies of investigation, the etiology and pathogenesis of clubfoot remains unknown. To date, no epidemiological studies have been conducted in Peru to assess possible genetic and environmental risk factors associated with this deformity. The purpose of this study was to evaluate specific environmental and socioeconomic factors that may increase the risk of clubfoot. A descriptive clinic-based study was conducted using structured questionnaires given to biological mothers of clinically confirmed clubfoot patients (n=72) and biological mothers of children between ages 0-18 with no first or second degree family history of clubfoot as controls (n=103). Phenotypic data from clubfoot subjects were also collected. We found that males were twice as likely to have clubfoot as females, and half of all clubfoot patients had bilateral clubfoot. There was no significant difference in the rate of left vs. right clubfoot. Infant birth in the winter months correlated with an increased risk of clubfoot (p=0.01476). Maternal characteristics found to be significantly associated with increased risk of clubfoot were young maternal age at conception (p=0.04369) and low maternal education (p=0.003245). Young paternal age also had a correlation with increased risk of clubfoot in the child (p=0.0371). Both paternal smoking (p=0.00001) and the presence of any household smoking (p=0.00003) were strongly associated with an increased risk of clubfoot.