Risk of limb deficiency defects associated with NAT1, NAT2, GSTT1, GSTM1, and NOS3 genetic variants, maternal smoking, and vitamin supplement intake

Maternal Cigarette Smoking and Congenital Upper and Lower Limb Differences: A Systematic Review and Meta-Analysis

Maternal smoking during pregnancy has been associated with adverse effects on foetal development, including congenital limb anomalies. This systematic review aimed to provide an updated assessment of the association between maternal smoking during pregnancy and the risk of congenital limb anomalies. A systematic search was conducted to identify relevant studies published up to February 2023. Studies reporting on the relationship between maternal smoking during pregnancy and congenital digital anomalies or congenital limb reduction defects were included. Two independent reviewers screened the studies, extracted data, and assessed the quality of the included studies. Meta-analyses were performed to estimate the pooled odds ratios with 95% confidence intervals using fixed and random-effects models. In total, 37 publications comprising 11 cohort and 26 case-control studies were included in the systematic review. The meta-analysis demonstrated a significant increased risk of congenital limb reduction defects (pooled OR: 1.27, 95% CI: 1.18-1.38) in infants born to mothers who smoked during pregnancy. Similarly, a significant relationship was observed for the development of polydactyly/syndactyly/adactyly when considered as a single group (pooled OR: 1.32, 95% CI: 1.25-1.40). Yet, in contrast, no significant association was observed when polydactyly (pooled OR: 1.06, 95% CI: 0.88-1.27) or syndactyly (pooled OR: 0.91, 95% CI: 0.77-1.08) were considered individually. This systematic review provides updated evidence of a significant relationship between maternal smoking during pregnancy and increased risk of congenital limb anomalies. These findings highlight the potential detrimental effects of smoking on foetal limb development and underscore the importance of smoking cessation interventions for pregnant women to mitigate these risks.

Maternal Risk Factors Associated with Limb Reduction Defects: Data from the Polish Registry of Congenital Malformations (PRCM)

Data from the Polish Registry of Congenital Malformations (PRCM) suggest that the prevalence of limb reduction defects (LRDs) in some Polish regions is significantly higher in comparison to that reported in the European Surveillance of Congenital Anomalies (EUROCAT) registry, but specific risk factors are still unknown. The objectives of this study were two-fold: to detect risk factors linked to isolated LRDs among Polish natives and to search for geospatial clusters of isolated LRDs to identify high-risk areas across the country. Among the 2,939,001 births accounted for in the PRCM, we determined that there were 852 children with distinct LRDs. Our data demonstrate that lower birth weight, prematurity, and maternal smoking history are strongly associated with isolated LRDs. Furthermore, our investigation pointed to various additional risk factors for isolated LRDs, including paternal education, gestational hypertension, upper respiratory tract infections, and exposure to anti-inflammatory drugs in the first trimester of pregnancy. We did not recognize statistically significant spatial or spatiotemporal clusters over the area of Poland using Kulldorff’s scan. Our study strengthens the hypothesis that maternal factors have an integral role in the etiology of isolated LRDs.

Diagnostic Clue in a Neonate with Amniotic Band Sequence

Amniotic band syndrome (ABS) is a set of congenital malformations that mainly affect the limbs and more rarely the skull, face, chest, and abdomen. Two main hypotheses have been proposed to explain the nature of the disorder: an intrinsic and extrinsic factor. We report a newborn with ABS presenting with several malformations involving both hands and foot. In this case, the malformative event localized at the hands and right foot without involvement of any other internal organs and is asymmetric which leads us to suppose the extrinsic factor as cause of the ABS.

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.

Maternal periconceptional exposure to cigarette smoking and congenital limb deficiencies

BACKGROUND

Congenital limb deficiencies (LD)s are characterised by the failure or disruption in formation of limbs or digits. Epidemiological research on maternal exposure to cigarette smoke and LDs is inconclusive.

METHODS

Data from the National Birth Defects Prevention Study were used to examine LDs and maternal exposure to active or passive cigarette smoke. Mothers of LD case (n = 906) and unaffected control (n = 8352) pregnancies from October 1997 through December 2007 reported on exposure type and quantity. Logistic regression was used to estimate adjusted odds ratio (OR) and 95% confidence interval [95% CI]; interactions with folic acid (FA) intake were tested.

RESULTS

For any LD, ORs were elevated for active (1.24 [95% CI 1.01, 1.53]), passive (home) (1.28 [95% CI 1.03, 1.59]), and 'active and passive' (1.34 [95% CI 1.05, 1.70]) exposures. The ORs for longitudinal LDs were elevated for passive (home) (1.62 [95% CI 1.14, 2.31]) and 'active and passive' (1.62 [95% CI 1.09, 2.41]) exposures. The OR for pre-axial LDs were elevated for any (1.39 [95% CI 1.01, 1.90]), active (1.53 [95% CI 1.03, 2.29]), passive (home) (1.82 [95% CI 1.23, 2.69]), and 'active and passive' (1.87 [95% CI 1.20, 2.92]) exposures. For lower limbs, ORs were elevated for passive (home) (1.44 [95% CI 1.01, 2.04]) and smoking 15 or more cigarettes/day (2.25 [95% CI 1.27, 3.97]). Interactions showed that ORs for any passive smoke exposure were 0.43 and 0.59 higher in the absence of FA intake for any and terminal transverse LDs.

CONCLUSIONS

Maternal active smoking and exposure to passive cigarette smoke emerged as a potential teratogen that affects limb and digit formation. FA was not found to mitigate the impact.

Rapid birth-and-death evolution of the xenobiotic metabolizing NAT gene family in vertebrates with evidence of adaptive selection

Background

The arylamine N-acetyltransferases (NATs) are a unique family of enzymes widely distributed in nature that play a crucial role in the detoxification of aromatic amine xenobiotics. Considering the temporal changes in the levels and toxicity of environmentally available chemicals, the metabolic function of NATs is likely to be under adaptive evolution to broaden or change substrate specificity over time, making NATs a promising subject for evolutionary analyses. In this study, we trace the molecular evolutionary history of the NAT gene family during the last ~450 million years of vertebrate evolution and define the likely role of gene duplication, gene conversion and positive selection in the evolutionary dynamics of this family.

Results

A phylogenetic analysis of 77 NAT sequences from 38 vertebrate species retrieved from public genomic databases shows that NATs are phylogenetically unstable genes, characterized by frequent gene duplications and losses even among closely related species, and that concerted evolution only played a minor role in the patterns of sequence divergence. Local signals of positive selection are detected in several lineages, probably reflecting response to changes in xenobiotic exposure. We then put a special emphasis on the study of the last ~85 million years of primate NAT evolution by determining the NAT homologous sequences in 13 additional primate species. Our phylogenetic analysis supports the view that the three human NAT genes emerged from a first duplication event in the common ancestor of Simiiformes, yielding NAT1 and an ancestral NAT gene which in turn, duplicated in the common ancestor of Catarrhini, giving rise to NAT2 and the NATP pseudogene. Our analysis suggests a main role of purifying selection in NAT1 protein evolution, whereas NAT2 was predicted to mostly evolve under positive selection to change its amino acid sequence over time. These findings are consistent with a differential role of the two human isoenzymes and support the involvement of NAT1 in endogenous metabolic pathways.

Conclusions

This study provides unequivocal evidence that the NAT gene family has evolved under a dynamic process of birth-and-death evolution in vertebrates, consistent with previous observations made in fungi.

Evaluation of genes involved in limb development, angiogenesis, and coagulation as risk factors for congenital limb deficiencies

We conducted a population-based case-control study of single nucleotide polymorphisms (SNPs) in selected genes to find common variants that play a role in the etiology of limb deficiencies (LDs). Included in the study were 389 infants with LDs of unknown cause and 980 unaffected controls selected from all births in New York State (NYS) for the years 1998-2005. We used cases identified from the NYS Department of Health (DOH) Congenital Malformations Registry. Genotypes were obtained for 132 SNPs in genes involved in limb development (SHH, WNT7A, FGF4, FGF8, FGF10, TBX3, TBX5, SALL4, GREM1, GDF5, CTNNB1, EN1, CYP26A1, CYP26B1), angiogenesis (VEGFA, HIF1A, NOS3), and coagulation (F2, F5, MTHFR). Genotype call rates were >97% and SNPs were tested for departure from Hardy-Weinberg expectations by race/ethnic subgroups. For each SNP, odds ratios (OR)s and confidence intervals (CI)s were estimated and corrected for multiple comparisons for all LDs combined and for LD subtypes. Among non-Hispanic white infants, associations between FGF10 SNPs rs10805683 and rs13170645 and all LDs combined were statistically significant following correction for multiple testing (OR = 1.99; 95% CI = 1.43-2.77; uncorrected P = 0.000043 for rs10805683 heterozygous genotype, and OR = 2.37; 95% CI = 1.48-3.78; uncorrected P = 0.00032 for rs13170645 homozygous minor genotype). We also observed suggestive evidence for associations with SNPs in other genes including CYP26B1 and WNT7A. Animal studies have shown that FGF10 induces formation of the apical ectodermal ridge and is necessary for limb development. Our data suggest that common variants in FGF10 increase the risk for a wide range of non-syndromic limb deficiencies.

NATb/NAT1*4 promotes greater arylamine N-acetyltransferase 1 mediated DNA adducts and mutations than NATa/NAT1*4 following exposure to 4-aminobiphenyl

N-acetyltransferase 1 (NAT1) is a phase II metabolic enzyme responsible for the biotransformation of aromatic and heterocyclic amine carcinogens such as 4-aminobiphenyl (ABP). NAT1 catalyzes N-acetylation of arylamines as well as the O-acetylation of N-hydroxylated arylamines. O-acetylation leads to the formation of electrophilic intermediates that result in DNA adducts and mutations. NAT1 is transcribed from a major promoter, NATb, and an alternative promoter, NATa, resulting in mRNAs with distinct 5'-untranslated regions (UTR). NATa mRNA is expressed primarily in the kidney, liver, trachea, and lung while NATb mRNA has been detected in all tissues studied. To determine if differences in 5'-UTR have functional effect upon NAT1 activity and DNA adducts or mutations following exposure to ABP, pcDNA5/FRT plasmid constructs were prepared for transfection of full-length human mRNAs including the 5'-UTR derived from NATa or NATb, the open reading frame, and 888 nucleotides of the 3'-UTR. Following stable transfection of NATb/NAT1*4 or NATa/NAT1*4 into nucleotide excision repair (NER) deficient Chinese hamster ovary cells, N-acetyltransferase activity (in vitro and in situ), mRNA, and protein expression were higher in NATb/NAT1*4 than NATa/NAT1*4 transfected cells (P < 0.05). Consistent with NAT1 expression and activity, ABP-induced DNA adducts and hypoxanthine phosphoribosyl transferase mutants were significantly higher (P < 0.05) in NATb/NAT1*4 than in NATa/NAT1*4 transfected cells following exposure to ABP. These differences observed between NATa and NATb suggest that the 5'-UTRs are differentially regulated.

Association between selected folate pathway polymorphisms and nonsyndromic limb reduction defects: a case-parental analysis

Inadequate folate status resulting from either genetic variation or nutritional deficiencies has been associated with an increased risk of congenital malformations including orofacial clefting, limb, cardiac and neural tube defects. Few epidemiological studies have examined the association between limb reduction defects (LRDs) and folate-related genetic polymorphisms other than MTHFR 677C→T. We conducted a case-parental analysis of 148 families who participated in the National Birth Defects Prevention Study to examine the association between nonsyndromic transverse and longitudinal LRDs with five single nucleotide polymorphisms (SNPs) in genes encoding enzymes in folate and methionine pathways. Log-linear Poisson regression, adapted for analysis of case-parental data assuming an additive genetic model, was used to estimate genetic relative risks and 95% confidence intervals for the association between LRDs and each SNP. Among women who did not take multivitamin supplements, the MTHFR 677T variant acts via the offspring's genome to increase the risk of LRDs. No association between LRDs and any fetal SNP was found among women who used multivitamin supplements. These results suggest the possibility that initiating folic acid supplementation prior to pregnancy may reduce the risk of having a LRD-affected pregnancy, especially in women whose offspring inherit one or two copies of the MTHFR 677T variant.

Functional effects of genetic polymorphisms in the N-acetyltransferase 1 coding and 3' untranslated regions

BACKGROUND

The functional effects of N-acetyltransferase 1 (NAT1) polymorphisms and haplotypes are poorly understood, compromising the validity of associations reported with diseases, including birth defects and numerous cancers.

METHODS

We investigated the effects of genetic polymorphisms within the NAT1 coding region and the 3'-untranslated region (3'-UTR) and their associated haplotypes on N- and O-acetyltransferase catalytic activities, and NAT1 mRNA and protein levels following recombinant expression in COS-1 cells.

RESULTS

1088T>A (rs1057126; 3'-UTR) and 1095C>A (rs15561; 3'-UTR) each slightly reduced NAT1 catalytic activity and NAT1 mRNA and protein levels. A 9-bp (TAATAATAA) deletion between nucleotides 1065 and 1090 (3'-UTR) reduced NAT1 catalytic activity and NAT1 mRNA and protein levels. In contrast, a 445G>A (rs4987076; V149I), 459G>A (rs4986990; T153T), and 640T>G (rs4986783; S214A) coding region haplotype present in NAT1*11 increased NAT1 catalytic activity and NAT1 protein, but not NAT1 mRNA levels. A combination of the 9-bp (TAATAATAA) deletion and the 445G>A, 459G>A, and 640T>G coding region haplotypes, both present in NAT1*11, appeared to neutralize the opposing effects on NAT1 protein and catalytic activity, resulting in levels of NAT1 protein and catalytic activity that did not differ significantly from the NAT1*4 reference.

CONCLUSIONS

Because 1095C>A (3'-UTR) is the sole polymorphism present in NAT1*3, our data suggest that NAT1*3 is not functionally equivalent to the NAT1*4 reference. Furthermore, our findings provide biologic support for reported associations of 1088T>A and 1095C>A polymorphisms with birth defects.

Update on the pharmacogenetics of NATs: structural considerations

The arylamine N-acetyltransferase (NAT) genes encode enzymes that catalyze the N-acetylation of aromatic amines and hydrazines and the O-acetylation of heterocyclic amines. These genes, which play a key role in cellular homeostasis as well as in gene-environment interactions, are subject to marked pharmacogenetic variation, and different combinations of SNPs in the human NAT genes lead to different acetylation phenotypes. Our understanding of the consequences of pharmacogenetic variability in NATs has recently been enhanced by structural studies showing that effects on protein folding, aggregation and turnover, as well as direct changes in active site topology, are involved. These developments pave the way for a better understanding of the role played by NATs in maintaining cellular homeostasis. In addition, the NATs represent a model for studying fundamental processes associated with protein folding and pharmacogenomic effects mediated by inheritance in human populations across a polymorphic region of the genome.

Genetic polymorphism in N-Acetyltransferase (NAT): Population distribution of NAT1 and NAT2 activity

N-Acetyltransferases (NAT) are key enzymes in the conjugation of certain drugs and other xenobiotics with an arylamine structure. Polymorphisms in NAT2 have long been recognized to modulate toxicity produced by the anti-tubercular drug isoniazid, with molecular epidemiologic studies suggesting a link between acetylator phenotype and increased risk for bladder cancer. Recent evidence indicates that the other major NAT isozyme, NAT1, is also polymorphic. The current analysis characterizes the main polymorphisms in both NAT2 and NAT1 in terms of their effect on enzyme activity and frequency in the population. Multiple NAT2 alleles (NAT2*5, *6, *7, and *14) have substantially decreased acetylation activity and are common in Caucasians and populations of African descent. In these groups, most individuals carry at least one copy of a slow acetylator allele, and less than 10% are homozygous for the wild type (fast acetylator) trait. Incorporation of these data into a Monte Carlo modeling framework led to a population distribution of NAT2 activity that was bimodal and associated with considerable variability in each population assessed. The ratio of the median to the first percentile of NAT2 activity ranged from 7 in Caucasians to 18 in the Chinese population. This variability indicates the need for more quantitative approaches (e.g., physiologically based pharmacokinetic [PBPK] modeling) to assess the full distribution of internal dose and adverse responses to aromatic amines and other NAT2 substrates. Polymorphisms in NAT1 are generally associated with relatively minor effects on acetylation function, with Monte Carlo analysis indicating less interindividual variability than seen in NAT2 analysis.

Maternal smoking and congenital heart defects

OBJECTIVES

In a population-based case-control study, we investigated the association between congenital heart defects and maternal smoking.

METHODS

The National Birth Defects Prevention Study enrolled 3067 infants with nonsyndromic congenital heart defects and their parents and 3947 infants without birth defects and their parents. Affected infants had > or = 1 of the following defects: conotruncal, septal, anomalous pulmonary venous return, atrioventricular septal defects, and left-sided or right-sided obstructive heart defects. Mothers of case and control infants were asked if they smoked during the periconceptional period, defined as 1 month before pregnancy through the first trimester. Maternal home and workplace exposure to tobacco smoke during the same period was also determined. Logistic regression was used to compute odds ratios and 95% confidence intervals while controlling for potential confounders.

RESULTS

Case infants were more likely to be premature and have lower birth weight than control infants. Women who smoked anytime during the month before pregnancy to the end of the first trimester were more likely to have infants with septal heart defects than women who did not smoke during this time period. This association was stronger for mothers who reported heavier smoking during this period. This relation was independent of potential confounding factors, including prenatal vitamin use, alcohol intake, maternal age, and race or ethnicity. Women who smoked > or = 25 cigarettes per day were more likely than nonsmoking mothers to have infants with right-sided obstructive defects. There was no increased risk of congenital heart defects with maternal exposure to environmental tobacco smoke.

CONCLUSIONS

Maternal smoking during pregnancy was associated with septal and right-sided obstructive defects. Additional investigation into the timing of tobacco exposure and genetic susceptibilities that could modify this risk will provide a more precise evidence base on which to build clinical and public health primary prevention strategies.

Structure-function analyses of single nucleotide polymorphisms in human N-acetyltransferase 1

Human N-acetyltransferase 1 (NAT1) alleles are characterized by one or more single nucleotide polymorphisms (SNPs) associated with rapid and slow acetylation phenotypes. NAT1 both activates and deactivates arylamine drugs and carcinogens, and NAT1 polymorphisms are associated with increased frequencies of many cancers and birth defects. The recently resolved human NAT1 crystal structure was used to evaluate SNPs resulting in the protein substitutions R64W, V149I, R187Q, M205V, S214A, D251V, E261K, and I263V. The analysis enhances knowledge of NAT1 structure-function relationships, important for understanding associations of NAT1 SNPs with genetic predisposition to cancer, birth defects, and other diseases.

Review on genetic variants and maternal smoking in the etiology of oral clefts and other birth defects

A spectrum of adverse pregnancy outcomes, including preterm birth, low birth weight, and birth defects has been linked with maternal smoking during pregnancy. This article includes a review of studies investigating interactions between genetic variants and maternal smoking in contributing to birth defects using oral clefting as a model birth defect. The primary gene-smoking studies for other major birth defects are also summarized. Gene-environment interaction studies for birth defects are still at an early stage with several mixed results, but evolving research findings have begun to document clinically and developmentally important interactions. As samples and data become increasingly available, more effort is needed in designing innovative analytical methods to study gene-environment interactions.

Functional effects of single nucleotide polymorphisms in the coding region of human N-acetyltransferase 1

Genetic variants of human N-acetyltransferase 1 (NAT1) are associated with cancer and birth defects. N- and O-acetyltransferase catalytic activities, Michaelis-Menten kinetic constants (K(m) and V(max)) and steady-state expression levels of NAT1-specific mRNA and protein were determined for the reference NAT1*4 and variant human NAT1 haplotypes possessing single nucleotide polymorphisms (SNPs) in the open reading frame. Although none of the SNPs caused a significant effect on steady-state levels of NAT1-specific mRNA, C97T(R33stop), C190T(R64W), C559T (R187stop) and A752T(D251V) each reduced NAT1 protein level and/or N- and O-acetyltransferase catalytic activities to levels below detection. G560A(R187Q) substantially reduced NAT1 protein level and catalytic activities and increased substrate K(m). The G445A(V149I), G459A(synonymous) and T640G(S214A) haplotype present in NAT1*11 significantly (P<0.05) increased NAT1 protein level and catalytic activity. Neither T21G(synonymous), T402C(synonymous), A613G(M205V), T777C(synonymous), G781A(E261K) nor A787G(I263V) significantly affected K(m), catalytic activity, mRNA or protein level. These results suggest heterogeneity among slow NAT1 acetylator phenotypes.

Functional analysis of the human N-acetyltransferase 1 major promoter: quantitation of tissue expression and identification of critical sequence elements

Arylamine N-acetyltransferase 1 (NAT1) plays an important role in the biotransformation of xenobiotics, and genetic variants have been implicated in susceptibility to cancer and birth defects. A specific and quantitative reverse transcription-polymerase chain reaction assay for transcription from the major NAT1 promoter detected high expression with limited variability in human tissues. A 213-base pair (bp) minimal promoter was identified by transfection of luciferase reporter constructs into MCF-7 and HepG2 cell lines. Alignment of the 213-bp region with paralogous and orthologous promoters revealed two conserved region segments, one of which overlaps a 16-bp perfect palindrome. Transfection of luciferase constructs with artificial mutations in the minimal promoter defined two sites important for promoter function. One of these sites included a close match to the Sp1 transcription factor binding consensus sequence. Electrophoretic mobility shift assays (EMSAs), followed by competitive and supershift analyses, confirmed the Sp1 binding. Mutation of the highly conserved portion of the 16-bp palindrome reduced promoter activity more than 3-fold, and an EMSA shift was detected with an oligonucleotide, 200L29, which spans this segment. The 200L29 EMSA shift could not be competed by consensus Sp1 or AP-2 oligonucleotides, and may represent binding of a transcription factor that is common to N-acetyltransferase genes in humans and other species.

ArylamineN-acetyltransferases

Arylamine N-acetyltransferases (NATs), known as drug- and carcinogen-metabolising enzymes, have had historic roles in cellular metabolism, carcinogenesis and pharmacogenetics, including epidemiological studies of disease susceptibility. NAT research in the past 5 years builds on that history and additionally paves the way for establishing the following new concepts in biology and opportunities in drug discovery: i) NAT polymorphisms can be used as tools in molecular anthropology to study human evolution; ii) tracing NAT protein synthesis and degradation within cells is providing insight into protein folding in cell biology; iii) studies on control of NAT gene expression may help to understand the increase in the human NAT isoenzyme, NAT1, in breast cancer; iv) a NAT homologue in mycobacteria plays an essential role in cell-wall synthesis and mycobacterial survival inside host macrophage, thus identifying a novel biochemical pathway; v) transgenic mice, with genetic modifications of all Nat genes, provide in vivo tools for drug metabolism; and vi) structures of NAT isoenzymes provide essential in silico tools for drug discovery.

Production of axial skeletal malformations with the nitric oxide synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in the mouse

BACKGROUND

To test whether the differentiating embryo is susceptible to the teratogenic effects of the nitric oxide (NO) synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME).

METHODS

ICR-(CD-1) mice received a single intraperitoneal injection of L-NAME at 90, 150, or 300 mg/kg on Gestation Day (GD) 8 or 9. Controls were treated with vehicle on GD 8 and 9. Teratological assessments were carried out near term (GD 18).

RESULTS

Maternal treatment with a single dose of L-NAME at 150 or 300 mg/kg on either GD 8 or 9 produced axial skeletal defects in the ICR (CD-1) mouse fetuses. Other treatment-related effects included increased embryo lethality and fetal growth restriction.

CONCLUSIONS

This study provides evidence that in utero exposure to L-NAME can affect organogenesis of the axial skeleton.

Risks of human limb deficiency anomalies associated with 29 SNPs of genes involved in homocysteine metabolism, coagulation, cell–cell interactions, inflammatory response, and blood pressure regulation

This study explored risks of limb deficiency anomalies associated with 29 single nucleotide polymorphisms (SNPs) of genes involved in homocysteine metabolism, coagulation, cell-cell interaction, inflammatory response, and blood pressure regulation. The authors genotyped 96 cases and 437 non-malformed controls from a California population-based case-control study (1987-1988 birth cohort). Increased risk of limb anomaly was observed for three SNPs: heterozygosity for F5 Arg506Gln, with an odds ratio (OR) of 2.5 (95% confidence interval (CI), 1.0, 6.5); heterozygosity for TNF (-376)G > A, OR 2.1 (0.7, 6.2); and homozygosity for NPPA 2238T > C, OR 4.0 (1.1, 15.4). We hypothesized that effects of variant genotypes in the presence of maternal smoking, and/or in the absence of supplement intake, may exceed effects of any of these factors alone. In particular, findings for polymorphisms in SERPINE1, ITGA2, SELE, TNF, LTA, NPPA, GNB3, and ADRB2 supported the hypotheses, both for smoking and for supplement intake. These results suggest involvement of genetic variation of biologically relevant candidate genes, and gene-environment interaction, for some limb anomalies whose pathogenesis may be related to altered vascular tone or integrity.