Genetics of clubfoot; recent progress and future perspectives

Fetal congenital talipes equinovarus: genomic abnormalities and obstetric follow-up results

OBJECTIVE

The etiology of congenital talipes equinovarus (CTEV) is unknown, and the relationship between chromosome microdeletion/microduplication and fetal CTEV is rarely reported. In this study, we retrospectively analyzed fetal CTEV to explore the relationship among the CTEV phenotype, chromosome microdeletion/microduplication, and obstetric outcomes.

METHODS

Chromosome karyotype analysis and single nucleotide polymorphism (SNP) array were performed for the 68 fetuses with CTEV.

RESULTS

An SNP array was performed for 68 fetuses with CTEV; pathogenic copy number variations (CNVs) were detected in eight cases (11.8%, 8/68). In addition to one case consistent with karyotype analysis, the SNP array revealed seven additional pathogenic CNVs, including three with 22q11.21 microdeletions, two with 17p12p11.2 microduplications, one with 15q11.2 microdeletions, and one with 7q11.23 microduplications. Of the seven cases carrying pathogenic CNVs, three were tested for family genetics; of these, one was de novo, and two were inherited from either the father or mother. In total, 68 fetuses with CTEV were initially identified, of which 66 cases successfully followed-up. Of these, 9 were terminated, 2 died in utero, and 55 were live births. In 9 cases, no clinical manifestations of CTEV were found at birth; the false-positive rate of prenatal ultrasound CTEVdiagnosis was thus 13.6% (9/66).

CONCLUSION

CTEV was associated with chromosome microdeletion/microduplication, the most common of which was 22q11.21 microdeletion, followed by 17p12p11.2 microduplication. Thus, further genomic detection is recommended for fetuses with CTEV showing no abnormalities on conventional karyotype analysis.

Clinical Characteristics and Whole Exome Sequencing Analysis in Serbian Cases of Clubfoot Deformity-Single Center Study

BACKGROUND

Recognized as one of the most serious musculoskeletal deformities, occurring in 1-2 per 1000 newborns, 80% of clubfeet are idiopathic while 20% present with associated malformations. The etiopathogenesis of clubfoot is described as multifactorial, including both genetic and environmental risk factors. The aim of this study was to analyze possible genetic causes of isolated and syndromic clubfoot in Serbian children, as well as to correlate clinical and genetic characteristics that would provide insight into clubfoot etiopathogenesis and possibly contribute to global knowledge about clinical features of different genetically defined disorders.

METHODS

We evaluated 50 randomly selected, eligible children with clubfoot aged 3 to 16 years that were initially hospitalized and treated at University Children's Hospital between November 2006 and November 2022. The tested parameters were gender, age, dominant foot, affected foot, degree of deformity, treatment, neuromuscular disorders, positive family history, and maternal smoking. According to the presence of defined genetic mutation/s by whole exome sequencing (WES), patients were separated into two groups: positive (with genetic mutation/s) and negative (without genetic mutation/s).

RESULTS

Seven patients were found to be positive, i.e., with genetic mutation/s. A statistically significant difference between categorical variables was found for families with a history of clubfoot, where more than half (57.14%) of patients with confirmed genetic mutation/s also had a family history of genetic mutation/s (p = 0.023).

CONCLUSIONS

The results from this study further expand the genetic epidemiology of clubfoot. This study contributes to the establishment of genetic diagnostic strategies in pediatric patients with this condition, which can lead to more efficient genetic diagnosis.

Epidemiological characterization of clubfoot: a population-based study of a surveillance program in Colombia

Clubfoot is a common musculoskeletal congenital abnormality, with a prevalence of 5-20 cases per 10 000 live births in low to middle-income countries. If left untreated, clubfoot causes severe consequences for the child: gait disturbances, reduced quality of life, and limited work opportunities. Our objective was to characterize clubfoot and determine its prevalence and associated risk factors in Bogotá and Cali, Colombia, from 2002 to 2020. A retrospective case-control study design was employed, analyzing data from birth defect reports provided by the Program for the Prevention and Follow-up of Congenital Defects and Orphan Diseases surveillance system. Cases included live births or stillbirths with clubfoot, while controls consisted of infants without congenital abnormalities, matched in terms of birth date and hospital. Prevalence was calculated considering a 95% confidence interval using Poisson distribution, and risk factors were assessed through adjusted odds ratios obtained by logistic regression model. Of 558 255 births, 861 cases of clubfoot were identified, 48.20% were postural clubfoot, and 15 cases were syndromic clubfoot. In Bogota, prevalence rate was 15.1 per 10 000 live births, whereas in Cali it was 17.29 per 10 000 live births. Family history of clubfoot within first-degree relatives was identified as a risk factor for clubfoot. Investigating risk factors for clubfoot holds significant importance in terms of preventing and reducing morbidity within this population. Helping to drive government and healthcare initiatives aimed at providing timely and effective treatment.

Human DNA Mutations and their Impact on Genetic Disorders

DNA is a remarkably precise medium for copying and storing biological information. It serves as a design for cellular machinery that permits cells, organs, and even whole organisms to work. The fidelity of DNA replication results from the action of hundreds of genes involved in proofreading and damage repair. All human cells can acquire genetic changes in their DNA all over life. Genetic mutations are changes to the DNA sequence that happen during cell division when the cells make copies of themselves. Mutations in the DNA can cause genetic illnesses such as cancer, or they could help humans better adapt to their environment over time. The endogenous reactive metabolites, therapeutic medicines, and an excess of environmental mutagens, such as UV rays all continuously damage DNA, compromising its integrity. One or more chromosomal alterations and point mutations at a single site (monogenic mutation) including deletions, duplications, and inversions illustrate such DNA mutations. Genetic conditions can occur when an altered gene is inherited from parents, which increases the risk of developing that particular condition, or some gene alterations can happen randomly. Moreover, symptoms of genetic conditions depend on which gene has a mutation. There are many different diseases and conditions caused by mutations. Some of the most common genetic conditions are Alzheimer's disease, some cancers, cystic fibrosis, Down syndrome, and sickle cell disease. Interestingly, scientists find that DNA mutations are more common than formerly thought. This review outlines the main DNA mutations that occur along the human genome and their influence on human health. The subject of patents pertaining to DNA mutations and genetic disorders has been brought up.

COL1A1 regulates the apoptosis of embryonic stem cells by mediating the PITX1/TBX4 signaling

PURPOSE

The purpose of this study is to explore the regulatory function of COL1A1 against the apoptosis of embryonic stem cells (ESCs) and the potential function in congenital talipes equinovarus (CTEV).

METHODS

Muscle tissues were collected from 20 children with CTEV and 20 children without CTEV, followed by detecting the expression of COL1A1 using the RT-PCR method. COL1A1 was knocked down in H1 and H9 human ESCs using the RNA interference technology, followed by determining the level of COL1A1, PITX1, TBX4, HOXD10, Fas, FasL, and Bax using the Western blotting assay.

RESULTS

COL1A1 was found markedly upregulated in muscle tissues of CTEV children. In H1 and H9 human ESCs, compared to the empty vector, COL1A1, PITX1, TBX4, HOXD10, Fas, FasL, and Bax were found notably downregulated after transfected with the siRNA targeting COL1A1.

CONCLUSION

COL1A1 induced the apoptosis of ESCs by mediating the PITX1/TBX4 signaling and might be a potential target for treating CTEV.

Investigating the association between vitamin D dietary intake during pregnancy and incidence of clubfoot in neonates

AIMS

Talipes equinovarus (clubfoot) is a congenital lower foot deformity that results from a neuromuscular deficiency, but the precise etiology remains elusive. Vitamin D is important for fetal neuromuscular development. In this study, we investigated the association between dietary vitamin D intake during pregnancy and incidence of clubfoot in neonates, since such a question has thus far been overlooked.

METHODS

We conducted a secondary analysis of data collected in the United States, between 2007 and 2011 for a case-control study of children born with clubfoot. Participating mothers were interviewed by telephone about dietary and other health and life-style indicators. Exposure to vitamin D was recorded as the average daily intake of dietary vitamin D over a period of 6 months before pregnancy began. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression.

RESULTS

The dataset included 2667 study participants, of which 663 were cases. Logistic regression showed no significant association between dietary vitamin D or log10 (Vitamin D) intake during pregnancy and incidence of clubfoot in neonates (OR = 1.00, CI = 1.00-1.00, OR = 1.51, CI = 0.83-2.82, respectively). No interaction in the regression model was found between vitamin D and other predictor variables. Results were not confounded by supplement intake of vitamin D during pregnancy.

CONCLUSIONS

Results show no evidence of an association between dietary vitamin D intake and incidence of clubfoot in neonates. The lack of association is not confounded by consumption of vitamin D supplements during pregnancy.

Flat-top talus after clubfoot treatment: a literature review

Flat-top talus (FTT) is a complication well-known to those treating clubfoot. Despite this, it receives little attention in textbooks, so our knowledge and understanding can be limited to anecdote and hearsay. In particular, its association with different treatments, especially the Ponseti method, is not well understood. This review provides some clarity on the possible pathoanatomical, radiological and iatrogenic causes of FTT. It summarises its prevalence following different treatments. It is seen after surgery, 'pre-Ponseti' casting and the Ponseti method, and seems least common following Ponseti. Potential surgical management strategies are also discussed.

Incidence and prevalence of congenital clubfoot in Apulia: a regional model for future prospective national studies

BACKGROUND

Congenital clubfoot is a fairly common and severe congenital malformation, most often of idiopathic origin. A smaller percentage of cases is related to chromosomal abnormalities and genetic syndromes. It is estimated that 0.5/1000 newborns are affected worldwide, with a male to female ratio of 2:1 and greater distribution in developing countries (80%). The "European Surveillance of Congenital Anomalies (EUROCAT)" reported clubfoot prevalence in European newborns, but data regarding Italy are missing or poor. We aim to provide detailed data on clubfoot incidence according to the Apulian Regional Registry on Congenital Malformations and to report current knowledge on clubfoot genetic factors.

METHODS

We extrapolated data from the Regional Registry of Congenital Malformations to evaluate incidence and prevalence of congenital clubfoot in Apulia, Italy over a period of four years (2015-2018). We also performed a narrative review focusing on genetic mutations leading to congenital clubfoot.

RESULTS

Over the period from 2015 to 2018 in Apulia, Italy, 124,017 births were recorded and 209 cases of clubfoot were found, accounting for an incidence rate of 1.7/1,000 and a prevalence rate of 1.6/1,000. Six families of genes have been reported to have an etiopathogenetic role on congenital clubfoot.

CONCLUSIONS

Incidence and prevalence of congenital clubfoot in Apulia, Italy, are comparable with those reported in the other Italian regions but higher than those reported in previous studies from Europe. Genetic studies to better classify congenital clubfoot in either syndromic or isolated forms are desirable.

Congenital Talipes Equinovarus Management and Outcomes: The Experiences of Pediatric Tertiary Centers in Abha, Saudi Arabia

BACKGROUND

Congenital talipes equinovarus (CTEV), also known as clubfoot, describes a range of foot abnormalities usually present at birth (congenital) in which a baby's foot is twisted out of shape or position. In clubfoot, tendons are shorter than usual. Clubfoot is a fairly common birth defect and is usually an isolated problem for an otherwise healthy newborn.

AIM

This study aimed to investigate the experiences of pediatric tertiary centers in Abha, Saudi Arabia, regarding the management, frequency, treatment options, and outcomes of CTEV.

METHODS

A retrospective chart review of pediatric patients with clubfoot was conducted to evaluate the number of cases, treatment options, and outcomes at Abha Maternity and Children Hospital and Khamis Mushait Maternity and Children Hospital. Data were extracted independently using prestructured data extraction forms. The collected data included demographic and medical information, family history, clinico-epidemiological information, risk factors, management options, and complications of clubfoot.

RESULTS

The study included 89 children with CTEV from the target hospitals. Their ages ranged from 20 days to six years, with a mean age of 10.5 ± 14.5 months. Of these, 57 (64%) were male. CTEV was unilateral in 53 (59.5%) cases and bilateral in 36 (40.5%) cases. The majority of the cases had isolated CTEV. Nearly all cases had Ponseti casting with a tendo-Achilles tenotomy (TAT) surgical procedure. Patient follow-up ranged from one week to three years, with an average follow-up of 3.1 months. Only three (3.4%) cases experienced recurrence of deformity after management.

CONCLUSION

Ponseti casting with the tendo-Achilles tenotomy approach emerged as the most commonly employed management option, demonstrating a low rate of recurrence.

Retrospective Case Analysis of 104 Cases of Talipes Equinus

A retrospective study of 104 patients (81 male and 23 females, the age range from 2 to 288days) with talipes equinus was conducted to explore the case factors associated with it. We analyzed and discussed the correlation of plaster correction times, age of first visit, gender, and birthplace of patients in the department and understood their correlation and causality. The data were analyzed using frequency analysis, normality test, chi-square goodness-of-fit test, chi-square test, and PLS regression. The findings are set out below. All the distributions of the number of plaster casts in the samples did not have normality. Therefore, we used the nonparametric test and partial least squares regression (PLS regression) and found that the number of plaster casts was more closely related to the age at first visit, gender, and birthplace and had a strong positive correlation. There was a negative correlation between the times of plaster correction and the compliance of braces. The lower the compliance of patients with braces, the more times the plaster correction will be conducted.

Prenatal Diagnosis of Talipes Equinovarus by Ultrasound and Chromosomal Microarray Analysis: A Chinese Single-Center Retrospective Study

Background: There are few studies on the detection rate by chromosomal microarray analysis (CMA) of the prenatal diagnosis of talipes equinovarus (TE) compared to conventional karyotyping. We aimed to explore the molecular etiology of fetal TE and examine the detection rate by CMA, which provides more information for the clinical screening and genetic counseling of TE. Methods: In this retrospective study, pregnancies diagnosed with fetal TE were enrolled and clinical data for all cases were retrieved from our medical record database, including demographic data for pregnancies, ultrasound findings, karyotype/CMA results, and pregnant and perinatal outcomes. Results: Among the 164 patients, 17 (10.4%) clinically significant variants were detected by CMA. In 148 singleton pregnancies, the diagnostic rate of clinically significant variants was significantly higher in the non-isolated TE group than in the isolated TE group (10/37, 27.0% vs. 6/111, 5.4%, P < 0.001). In twin pregnancies, 1 (6.3%) pathogenic copy number variant was present in the other 16 twin pregnancies. Conclusions: This study demonstrates that CMA is useful for the prenatal genetic diagnosis of fetal TE. Fetal TE with the associated structural malformation correlates with a higher probability of clinically significant variants. This data may aid prenatal diagnosis and genetic counseling for fetal TE.

Empirical Investigation of Genomic Clusters Associated With Height and the Risk of Postmenopausal Breast and Colorectal Cancer in the Netherlands Cohort Study

We empirically investigated genomic clusters associated with both height and postmenopausal breast cancer (BC) or colorectal cancer (CRC) (or both) in the Netherlands Cohort Study to unravel shared underlying mechanisms between height and these cancers. The Netherlands Cohort Study (1986-2006) includes 120,852 participants (case-cohort study: nsubcohort = 5,000; 20.3 years of follow-up). Variants in clusters on chromosomes 2, 4, 5, 6 (2 clusters), 10, and 20 were genotyped using toenail DNA. Cluster-specific genetic risk scores were modeled in relation to height and postmenopausal BC and CRC risk using age-adjusted linear regression and multivariable-adjusted Cox regression, respectively. Only the chromosome 10 cluster risk score was associated with all 3 phenotypes in the same sex (women); that is, it was associated with increased height (βcontinuous = 0.34, P = 0.014), increased risk of hormone-receptor-positive BC (for estrogen-receptor-positive BC, hazard ratio (HRcontinuous score) = 1.10 (95% confidence interval (CI): 1.02, 1.20); for progesterone-receptor-positive BC, HRcontinuous score = 1.15 (95% CI: 1.04, 1.26)), and increased risk of distal colon (HRcontinuous score = 1.13, 95% CI: 1.01, 1.27) and rectal (HRcontinuous score = 1.14, 95% CI: 0.99, 1.30) cancer. The chromosome 10 cluster variants were all annotated to the zinc finger MIZ-type containing 1 gene (ZMIZ1), which is involved in androgen receptor activity. This suggests that hormone-related growth mechanisms could influence both height and postmenopausal BC and CRC.

Association Between TPM1 Gene Polymorphisms and Idiopathic Congenital Talipes Equinovarus Risk in a Chinese Population

Background: Idiopathic congenital talipes equinovarus (ICTEV) is one of the most common congenital deformities of children, and dysplasia of the striated muscle may be one of the causes of ICTEV. Previous studies have shown that polymorphisms of the rs4075583 SNP in the tropomyosin gene 1 (TPM1) were associated with ICTEV in Caucasian children. However, there are no studies investigating the correlations of TPM gene polymorphisms with the risk of ICTEV in Chinese children. Methods: We conducted a case-control study, including 430 children with ICTEV and 891 ICTEV-free children. We explored the potential correlations of three TPM gene polymorphisms (TPM1/rs4075583 G>A, tropomyosin gene 2 (TPM2)/rs2145925 C>T, and TPM2/rs2025126 G>A) with ICTEV risk. The three single nucleotide polymorphisms (SNPs) were genotyped using a TaqMan method. We calculated the odds ratios (ORs) and adjusted ORs and their 95% confidence intervals (CIs) to explore the associations between these selected SNP polymorphisms and ICTEV. Results: TPM1 rs4075583 A was found to be associated with an increased ICTEV risk (AA vs. GG: adjusted OR = 1.70, 95% CI = 1.15-2.49, p = 0.007; and GG/GA vs. AA: adjusted OR = 1.62, 95% CI = 1.14-2.31, p = 0.0071) after adjusting for age and sex. In addition, a risk effect of rs4075583 GA/AA with ICETV was observed for patients with affected right feet (adjusted OR = 1.62, 95% CI = 1.10-2.39, p = 0.014) in the stratified analysis. However, there were no significant differences in the risk for ICTEV associated with the rs2145925 and rs2025126 polymorphisms. Conclusion: These results indicate that the TPM1 rs4075583 G > A polymorphism is associated with ICTEV risk in a southern Chinese population; however, this finding needs to be confirmed in larger studies and through mechanistic studies.

Co-occurrence of orofacial clefts and clubfoot phenotypes in a sub-Saharan African cohort: Whole-exome sequencing implicates multiple syndromes and genes

Background

Orofacial clefts (OFCs) are congenital malformations of the face and palate, with an incidence of 1 per 700 live births. Clubfoot or congenital talipes equinovarus (CTEV) is a three‐dimensional abnormality of the leg, ankle, and feet that leads to the anomalous positioning of foot and ankle joints and has an incidence of 1 per 1000 live births. OFCs and CTEV may occur together or separately in certain genetic syndromes in addition to other congenital abnormalities. Here, we sought to decipher the genetic etiology of OFC and CTEV that occurred together in six probands.

Methods

At the time of recruitment, the most clinically obvious congenital anomalies in these individuals were the OFC and CTEV. We carried out whole‐exome sequencing (WES) on DNA samples from probands and available parents employing the Agilent SureSelect XT kit and Illumina HiSeq2500 platform, followed by bioinformatics analyses. WES variants were validated by clinical Sanger Sequencing.

Results

Of the six probands, we observed probable pathogenic genetic variants in four. In three probands with probable pathogenic genetic variants, each individual had variants in three different genes, whereas one proband had probable pathogenic variant in just one gene. In one proband, we observed variants in DIS3L2, a gene associated with Perlman syndrome. A second proband had variants in EPG5 (associated with Vici Syndrome), BARX1 and MKI67, while another proband had potentially etiologic variants in FRAS1 (associated with Fraser Syndrome 1), TCOF1 (associated with Treacher Collins Syndrome 1) and MKI67. The last proband had variants in FRAS1, PRDM16 (associated with Cardiomyopathy, dilated, 1LL/Left ventricular noncompaction 8) and CHD7 (associated with CHARGE syndrome/Hypogonadotropic hypogonadism 5 with or without anosmia).

Conclusion

Our results suggest that clubfoot and OFCs are two congenital abnormalities that can co‐occur in certain individuals with varying genetic causes and expressivity, warranting the need for deep phenotyping.

A Community Audit of 300 "Drop-Out" Instances in Children Undergoing Ponseti Clubfoot Care in Bangladesh-What Do the Parents Say?

Introduction: Drop-out before treatment completion is a vexing problem for all clubfoot clinics. We and others have previously identified better engagement with parents as a crucial method of ameliorating incomplete clubfoot treatment, which increases deformity relapse. Materials and methods: The novel use of community facilitators enabled an audit of over 300 families who had dropped-out from a child’s clubfoot treatment. A questionnaire standardized the parent interviews. Parents were encouraged to present for clinical review of their child’s clubfeet. Results: When treatment was discontinued for six months, 309 families were audited. A social profile of families was developed, showing that most lived in tin houses with one working family member, indicating low affluence. Family issues, brace difficulty, travel distances, and insufficient understanding of ongoing bracing and follow-up were the main reasons for discontinuing treatment. Overt deformity relapse was found in 9% of children, while half of the children recommenced brace use after review. Conclusions: Identifying families at risk of dropping out from clubfoot care enables support to be instigated. Our findings encourage clinicians to empathize with parents of children with clubfoot deformity. The parent load indicator, in parallel with the initial clubfoot severity assessment, may help clinicians to better appreciate the demand that treatment will place on parents, the associated risk of drop-out, and the opportunity to enlist support.

Gene Environment Interactions Between the COL9A1 Gene and Maternal Drinking of Alcohol Contribute to the Risk of Congenital Talipes Equinovarus

Background: Previous studies have indicated that both genetic and environmental factors contribute to the risk of congenital talipes equinovarus (CTEV). The COL9A1 gene encodes one of the three alpha chains of type IX collagen, which is a key collagen component of hyaline cartilage. Our study aimed to evaluate the effect of COL9A1 gene polymorphisms on susceptibility to CTEV in the Han Chinese population. Methods: A total of 2205 unrelated subjects comprising 692 CTEV patients and 1513 healthy controls were recruited. Demographic and characteristic information was collected, including maternal smoking and maternal drinking. Genetic association analyses and gene-environment interaction analyses were conducted based on the genotypic data of 36 tag single nucleotide polymorphisms (SNPs). Results: Although there was no association between genotyped SNPs and CTEV, a gene-environment interaction signal between SNP rs6455357 and maternal drinking was identified. Furthermore, significant heterogeneity was identified for this interaction signal when stratified by maternal drinking. For subjects with never maternal drinking, the A allele of SNP rs6455357 was significantly associated with a decreased risk of CTEV. In contrast, the A allele was associated with an increased risk of CTEV in the "occasional" and "often" groups. Conclusions: Our results indicate a combined effect of genetics and environmental factors on the etiology of CTEV. This study increases our understanding of the etiology of CETV and provides useful information for genetic counseling for at-risk families for the development of prevention programs and improved management.

The relationship between isolated pes equinovarus and aneuploidies and perinatal outcomes: Results of a tertiary center

Objective

Congenital pes equinovarus (PEV) is the most common congenital deformity of the foot, characterized by plantar flexion with a frequency of 0.2-0.3%. It can be diagnosed from the 12^th week of pregnancy. Non-isolated cases tend to be syndromic and complex. We aimed to evaluate the results of perinatally diagnosed isolated PEV.

Materials and Methods

This was a retrospective cohort study conducted between March 2015-March 2020. Women who presented for fetal anomaly screening or were referred due to any suspected fetal anomaly were subjected to detailed fetal anomaly scans and checked for the presence of PEV. Karyotype analysis was discussed for patients with PEV. Pregnancy termination was recommended for those with chromosomal/life-threatening anomalies. The diagnosis was confirmed by postnatal examination/autopsy. Postnatal diagnosis was accepted as false-positive in those with no PEV.

Results

One-hundred thirty-eight patients were found to have PEV, 41 (29.7%) of which were isolated. In the isolated group, the false-positive rate in the first trimester was significantly higher compared with the second trimester, 50%/15.3%, respectively (p<0.05). Chromosomal anomalies were detected in 2 (4.8%) patients in the isolated group. Termination was performed to 1 (2.4%) patients due to trisomy 21. In the non-isolated group, chromosomal anomalies were detected in 13 (13.4%) patients, and termination was recommended. Termination was also recommended to 18 (18.5%) patients due to anomalies incompatible with life. In the postnatal evaluation, the surgical treatment rate in the isolated/non-isolated groups was 6%/39.7% (p<0.05).

Conclusion

When PEV is diagnosed, detailed fetal anomaly screening must be performed, patients should be informed about the chromosomal anomaly risk. High false-positive rates in the first trimester should be kept in mind for diagnosis. Karyotype analysis should be recommended also to isolated cases. It should be remembered that some neuromuscular/skeletal system anomalies may occur for the first time in the postnatal period in isolated cases.

What a paediatrician should know about congenital clubfoot

Clubfoot is the most frequent congenital malformation of the foot, affecting more than 1–2 subjects per 1.000 newborns. Without appropriate treatment, a child with congenital clubfoot will never be able to walk physiologically with a dramatic impact on the quality of life. In the last decades, different corrective solutions have been proposed, and there is rising scientific evidence that the Ponseti non-invasive method is safe and effective in the treatment of the clubfoot. So, what should a general paediatrician know about this condition and what should he concretely do in the suspect of a congenital clubfoot?

Integrated Bioinformatics Analysis Reveals Potential Pathway Biomarkers and Their Interactions for Clubfoot

Background

Congenital talipes equinovarus (clubfoot), one of the most regular pediatric congenital skeletal anomalies, seriously affects the normal growth and development of about 1 in 1000 newborns. Although it has been investigated widely, the etiology and pathogenesis of clubfoot are still controversial.

Material/Methods

g: Profiler, NetworkAnalyst and WebGestalt were used to probe the enriched signaling pathways by using the Gene Ontology (GO), Human Phenotype Ontology (HP), Kyoto Encyclopedia of Genes and Genomes (KEGG), Reactome (REAC), and WikiPathways (WP) databases. Large numbers of enriched signaling pathways were identified using the integrated bioinformatics enrichment analyses.

Results

Apoptosis or programmed cell death (PCD), disease, muscle contraction, metabolism, and immune system were the top functions. Embryo or organ morphogenesis and development, cell or muscle contraction, and apoptosis were the top biological processes, and cell/muscle contraction and apoptosis were the top molecular functions using enriched GO terms analysis. There were a large number of complex interactions in the genes, enriched pathways, and transcription factor (TF)-miRNA co-regulatory networks. Transcription factors such as FOXN3, GLI3, HOX, and NCOR2 family regulated the gene expression of APAF1, BCL2, BID, CASP, MTHFR, and TPM family.

Conclusions

The results of bioinformatics enrichment analysis not only supported the previously proposed hypotheses, e.g., extracellular matrix (ECM) abnormality, fetal movement reducing, genetic abnormality, muscle abnormality, neurological abnormality, skeletal abnormality and vascular abnormality, but also indicated that cellular or immune responses to external stimulus, molecular transport and metabolism may be new etiological mechanisms in clubfoot.

Clubfoot deformity in the Solomon Islands: Melanesian versus Polynesian ethnicity, a retrospective cohort study

PURPOSE

Congenital talipes equinovarus (CTEV) has a high incidence in the South Pacific, with New Zealand Maori and Polynesian rates of up to seven per 1000 live births, at least five times higher than the Caucasian population. A genetic component is suggested to explain this, however, there is little information regarding the difference of incidence between Polynesian and Melanesian ethnicity in the South Pacific. Our aim was to investigate the effects of ethnicity on the incidence of CTEV in the Solomon Islands, specifically comparing Melanesian and Polynesian ethnicity.

METHODS

Between 2011 and 2017, data was collected in the Solomon Islands from over 40 clinics upon introduction of the Ponseti programme for treatment of CTEV. Records were kept using the validated Global Clubfoot Initiative data form. Ethnicity was documented, including family history.

RESULTS

In total, 138 children presented during this period, with 215 affected feet reviewed and treated. In all, 74% of children had solely Melanesian parents and 6% Polynesian. Using the general population ethnic breakdown of 95.3% Melanesian and 3.1% Polynesian, the odds of CTEV in children of Melanesian parents were 0.41 times lower compared with the odds in children of Polynesian parents.

CONCLUSION

The results indicate that in the Solomon Islands, CTEV in Melanesian children was less than half as likely to occur in Polynesian children. Our findings also support the theories of minimal Polynesian genetic material persisting in the Solomon Islands and a different genetic risk of CTEV between Polynesians and Melanesians.

LEVEL OF EVIDENCE

III.

Rare and de novo duplications containing SHOX in clubfoot

Introduction

Congenital clubfoot is a common birth defect that affects at least 0.1% of all births. Nearly 25% cases are familial and the remaining are sporadic in inheritance. Copy number variants (CNVs) involving transcriptional regulators of limb development, including PITX1 and TBX4, have previously been shown to cause familial clubfoot, but much of the heritability remains unexplained.

Methods

Exome sequence data from 816 unrelated clubfoot cases and 2645 in-house controls were analysed using coverage data to identify rare CNVs. The precise size and location of duplications were then determined using high-density Affymetrix Cytoscan chromosomal microarray (CMA). Segregation in families and de novo status were determined using qantitative PCR.

Results

Chromosome Xp22.33 duplications involving SHOX were identified in 1.1% of cases (9/816) compared with 0.07% of in-house controls (2/2645) (p=7.98×10⁻⁵, OR=14.57) and 0.27% (38/13592) of Atherosclerosis Risk in Communities/the Wellcome Trust Case Control Consortium 2 controls (p=0.001, OR=3.97). CMA validation confirmed an overlapping 180.28 kb duplicated region that included SHOX exons as well as downstream non-coding regions. In four of six sporadic cases where DNA was available for unaffected parents, the duplication was de novo. The probability of four de novo mutations in SHOX by chance in a cohort of 450 sporadic clubfoot cases is 5.4×10^–10.

Conclusions

Microduplications of the pseudoautosomal chromosome Xp22.33 region (PAR1) containing SHOX and downstream enhancer elements occur in ~1% of patients with clubfoot. SHOX and regulatory regions have previously been implicated in skeletal dysplasia as well as idiopathic short stature, but have not yet been reported in clubfoot. SHOX duplications likely contribute to clubfoot pathogenesis by altering early limb development.

The influence of laterality, sex and family history on clubfoot severity

PURPOSE

Epidemiological studies on idiopathic clubfeet have shown a typical distribution consistent across ethnic groups: bilaterality in about 50% of cases and a male to female ratio of 2:1. Whether this corresponds also to differences in severity according to laterality and sex has been poorly evaluated. As well, the correlation between family history and severity has not been previously investigated. The aim of this study was to investigate how laterality, sex and family history influence severity and treatment.

METHODS

In all, 97 infants with idiopathic clubfoot (81 male, 16 female; 55 unilateral, 42 bilateral; 19 with a first or second-degree relative affected) consecutively treated with Ponseti method were prospectively enrolled. Initial severity (according to Dimeglio and Pirani scores) and treatment (number of casts and need for tenotomy) were analyzed in the different subgroups.

RESULTS

Initial severity according to Pirani (p = 0.020) and Dimeglio score (p = 0.006), number of casts (p = 0.000) and tenotomy (p = 0.045) were significantly higher in bilateral than in unilateral cases. In bilateral cases, a significant correlation was found between the right and left foot of each patient in terms of initial severity, number of casts and tenotomy performed. No statistically significant difference was found according to sex and family history.

CONCLUSIONS

This study has confirmed the different behaviour of bilateral cases reported by previous studies; bilateral cases are more severe and show similar features in their right and left foot. This could be the result of different pathogenic mechanisms, likely on a genetic basis. Sex and family history did not seem to influence severity.

LEVEL OF EVIDENCE

Level of evidence II.

Whole‑exome sequencing study identifies two novel rare variations associated with congenital talipes equinovarus

Congenital talipes equinovarus (CTEV) is a common birth defect with an unclear genetic pathogenesis that results from both genetic and environmental factors. The present study aimed to identify novel variants in patients with CTEV using whole‑exome sequencing (WES) and to investigate the genetic factors responsible for the development of CTEV.A cohort of nine neonates/infants with suspected CTEV was recruited. Subsequently, sequential tests, including chromosome karyotyping and WES, were performed for each of the participants. Familial validation was performed using Sanger sequencing and low‑coverage copy‑number variation (CNV) sequencing. A novel CNV containing the mediator complex subunit 13L gene at 12q24.21‑q24.23 was detected by WES and further investigated by CNVseq. Additionally, a novel de novo missense variation, transforming growth factor‑β receptor 2: c.1280T>C, was identified by WES and further investigated by Sanger sequencing. The two identified variations were hypothesized to be causative genetic factors for the development of CTEV in the two cases the variations were identified in. In the present study, two pathogenic variations (one CNV and one single‑base variation) were detected in two Chinese families with CTEV. The results of the present study may aid in investigating the molecular basis of CTEV; however, further investigation is required.

New phenotype of DCTN1-related spectrum: early-onset dHMN plus congenital foot deformity

OBJECTIVE

To describe the clinical and genetic features of two patients with different phenotypes due to various Dynactin 1 (DCTN1) gene mutations and further explore the phenotype-genotype relationship.

METHODS

Patient 1 is a 23-year-old man with congenital foot deformity and life-long distal muscle weakness and atrophy. Patient 2 is a 48-year-old woman with adult-onset progressive weakness, lower limbs atrophy, and pyramid bundle signs. Electrophysiology test showed normal nerve conduction velocity of both patients and neurogenic changes in needle electromyography. Open sural nerve biopsy for Patient 1 showed slight loss of myelinated nerve fibers. Both patients were performed with whole-exome sequencing followed by functional study of identified variants.

RESULTS

Two mutations in DCTN1 gene were identified in Patient 1 (c.626dupC) and Patient 2 (c.3823C>T), respectively. In vitro, the wild type mostly located in cytoplasm and colocalized with α-tubulin. However, c.626dupC tended to be trapped into nuclear and the c.3823C>T formed cytoplasmic aggregates, both losing colocalization with α-tubulin. Western blotting showed a truncated mutant with less molecular weight of c.626dupC was expressed.

INTERPRETATION

We identify two novel DCTN1 mutations causing different phenotypes: (1) early-onset distal hereditary motor neuropathy plus congenital foot malformation and (2) amyotrophic lateral sclerosis, respectively. We provide the initial evidence that foot developmental deficiency probably arises from subcellular localizing abnormality of Dynactin 1, revealing DCTN1-related spectrum is still expanding.

Integrated bioinformatics analysis of potential pathway biomarkers using abnormal proteins in clubfoot

Background

As one of the most common major congenital distal skeletal abnormalities, congenital talipes equinovarus (clubfoot) affects approximately one in one thousandth newborns. Although several etiologies of clubfoot have been proposed and several genes have been identified as susceptible genes, previous studies did not further explore signaling pathways and potential upstream and downstream regulatory networks. Therefore, the aim of the present investigation is to explore abnormal pathways and their interactions in clubfoot using integrated bioinformatics analyses.

Methods

KEGG, gene ontology (GO), Reactome (REAC), WikiPathways (WP) or human phenotype ontology (HP) enrichment analysis were performed using WebGestalt, g:Profiler and NetworkAnalyst.

Results

A large number of signaling pathways were enriched e.g. signal transduction, disease, metabolism, gene expression (transcription), immune system, developmental biology, cell cycle, and ECM. Protein-protein interactions (PPIs) and gene regulatory networks (GRNs) analysis results indicated that extensive and complex interactions occur in these proteins, enrichment pathways, and TF-miRNA coregulatory networks. Transcription factors such as SOX9, CTNNB1, GLI3, FHL2, TGFBI and HOXD13, regulated these candidate proteins.

Conclusion

The results of the present study supported previously proposed hypotheses, such as ECM, genetic, muscle, neurological, skeletal, and vascular abnormalities. More importantly, the enrichment results also indicated cellular or immune responses to external stimuli, and abnormal molecular transport or metabolism may be new potential etiological mechanisms of clubfoot.

Generation and characterization of a human iPSC line derived from congenital clubfoot amniotic fluid cells

A human induced pluripotent stem cell (iPSC) line (SMBCi002-A) was established from amniocytes (amniotic fluid cells, AFDCs) from a 16-week-old female fetus with clubfoot. Reprogramming and enhancing factors OCT4, SOX2, KLF4, MYC, LIN28 and EBNA1 were delivered using a nonintegrative strategy based on episomal plasmids. Validation assays indicated that this iPSC line has full pluripotency, differentiation potential and genetic stability. Currently, the etiology and mechanism of clubfoot remain unclear; therefore, this in vitro cellular model would provide a useful resource for understanding the pathology of this disease.

Retinoic Acid Promotes Retinoic Acid Signaling by Suppression of Pitx1 In Tendon Cells: A Possible Mechanism of a Clubfoot-Like Phenotype Induced by Retinoic Acid

Background

The pathogenesis of idiopathic congenital clubfoot (CCF) is unknown. Although some familial patients have Pitx1 mutations, and the Pitx1+/− genotype causes a clubfoot-like phenotype in mice, the mechanism of Pitx1-induced CCF is unknown.

Material/Methods

We used tibialis anterior tendon samples to detect the expression of Pitx1 in idiopathic and neurogenic clubfoot patients. After obtaining Sprague-Dawley (SD) rat Achilles tendon cells, the expression of Pitx1 was knocked down by SiRNA. After 48 h of culture, mass spectrometry was used to quantitatively analyze proteins. Then, Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to assess the downstream pathway of PITX1. The relationship between Pitx1 and the promoter region of deacetylase 1 (Sirtuin-1 and Sirt1) was examined by luciferase and ChIP assays.

Results

We found that Pitx1 expression in the tendon samples of idiopathic CCF patients was downregulated. Mass spectrometry analysis revealed that the inhibition of Pitx1 induced the downregulation of Sirt1 expression in tendon cells. Luciferase and ChIP assays confirmed that Pitx1 binds to the promoter region of SIRT1 and promotes Sirt1 gene transcription. Further results showed that, after the inhibition of Pitx1 in tendon cells, CRABP2 acetylation increased, the nuclear import of CRABP2 was enhanced, and the expression of RARβ2 increased. After the inhibition of Pitx1, RARβ2 expression was further increased by RA treatment in tendon cells. In the presence of retinoic acid, the expression of Pitx1 was inhibited in tendon cells.

Conclusions

Pitx1 binds to the promoter region of SIRT1 and promotes the transcription of SIRT1. Positive feedback occurs between RA signaling and Pitx1.

TAZ and myostatin involved in muscle atrophy of congenital neurogenic clubfoot

BACKGROUND

Muscular atrophy is the basic defect of neurogenic clubfoot. Muscle atrophy of clubfoot needs more scientific and reasonable imaging measurement parameters to evaluate. The Hippo pathway and myostatin pathway may be directly correlated in myogenesis. In this study, we will use congenital neurogenic clubfoot muscle atrophy model to verify in vivo. Further, the antagonistic mechanism of TAZ on myostatin was studied in the C2C12 cell differentiation model.

AIM

To identify muscle atrophy in fetal neurogenic clubfoot by ultrasound imaging and detect the expression of TAZ and myostatin in gastrocnemius muscle. To elucidate the possible mechanisms by which TAZ antagonizes myostatin-induced atrophy in an in vitro cell model.

METHODS

Muscle atrophy in eight cases of fetal unilateral clubfoot with nervous system abnormalities was identified by 2D and 3D ultrasound. Western blotting and immunostaining were performed to detect expression of myostatin and TAZ. TAZ overexpression in C2C12 myotubes and the expression of associated proteins were analyzed by western blotting.

RESULTS

The maximum cross-sectional area of the fetal clubfoot on the varus side was reduced compared to the contralateral side. Myostatin was elevated in the atrophied gastrocnemius muscle, while TAZ expression was decreased. They were negatively correlated. TAZ overexpression reversed the diameter reduction of the myotube, downregulated phosphorylated Akt, and increased the expression of forkhead box O4 induced by myostatin.

CONCLUSION

Ultrasound can detect muscle atrophy of fetal clubfoot. TAZ and myostatin are involved in the pathological process of neurogenic clubfoot muscle atrophy. TAZ antagonizes myostatin-induced myotube atrophy, potentially through regulation of the Akt/forkhead box O4 signaling pathway.

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.

Additional challenges in children with idiopathic clubfoot: is it just the foot?

PURPOSE

Treatment of idiopathic clubfoot (IC) has improved since the introduction of the Ponseti method. However, relapses are still common and primarily related to non-adherence to the brace regime. Our hypothesis was that IC might be more than just a structural deformity. Based on three studies, the aim of this paper was to provide an overview of findings regarding additional challenges within IC.

METHODS

In total, 153 children with IC and 137 control children participated in the studies. The first study assessed gross motor skills in six motor tasks using the Clubfoot Assessment Protocol. The second and third studies surveyed neurodevelopmental difficulties (NDDs) using the Five to Fifteen (FTF) questionnaire and health-related quality of life (HRQoL) using the EuroQol-5D youth.

RESULTS

A high percentage of gross motor deviations were found in children with IC compared with controls, and those correlated poorly with clubfoot severity and foot movement. Children with IC had a higher prevalence of NDDs on the FTF compared with the control group, including the domains: motor skills, perception and language. One-third of children with IC were defined as at risk of developmental disorders. In this subgroup, parents were less satisfied with the outcome of clubfoot treatment and the children reported worse HRQoL than those without NDDs.

CONCLUSION

The findings suggest additional challenges in children with IC, such as NDDs, apparently affecting both clubfoot treatment outcome and HRQoL. Thus, awareness of these challenges could be vital to further optimize treatment and support, for example, with regards to brace adherence.

LEVEL OF EVIDENCE

II - Prognostic study.

A novel enhancer near the Pitx1 gene influences development and evolution of pelvic appendages in vertebrates

Vertebrate pelvic reduction is a classic example of repeated evolution. Recurrent loss of pelvic appendages in sticklebacks has previously been linked to natural mutations in a pelvic enhancer that maps upstream of Pitx1. The sequence of this upstream PelA enhancer is not conserved to mammals, so we have surveyed a large region surrounding the mouse Pitx1 gene for other possible hind limb control sequences. Here we identify a new pelvic enhancer, PelB, that maps downstream rather than upstream of Pitx1. PelB drives expression in the posterior portion of the developing hind limb, and deleting the sequence from mice alters the size of several hind limb structures. PelB sequences are broadly conserved from fish to mammals. A wild stickleback population lacking the pelvis has an insertion/deletion mutation that disrupts the structure and function of PelB, suggesting that changes in this ancient enhancer contribute to evolutionary modification of pelvic appendages in nature.

Club foot in association with the 22q11.2 deletion syndrome: An observational study

The 22q11.2 Deletion Syndrome (22q11.2DS) occurs in ~1:3,000-6,000 individuals. Features less typically associated with 22q11.2DS, such as orthopedic manifestations, may be overlooked or may not lead to appropriate diagnostic testing. Club foot has a general population prevalence of ~1:1,000 and has been occasionally described in association with 22q11.2DS. Our hypothesis is that the prevalence of club foot is higher in patients with 22q11.2DS. We performed a retrospective review in two specialized 22q11.2DS centers to determine the prevalence of club foot. "True club foot" requires treatment (either conservative or surgical), therefore we only included those patients with proof of treatment. We investigated whether congenital heart disease (CHD) and/or cleft palate were associated with the presence of club foot within 22q11.2DS. The records of 1,466 patients were reviewed. Of these, 48 (3.3%) had confirmation of club foot (95% Confidence Interval: 2.4-4.3): 22 (46%) had a bilateral, 12 (25%) left, and 14 (29%) right club foot. Within our study, neither a CHD and/or a cleft palate were associated with a club foot. The prevalence of club foot in 22q11.2DS is 30 times higher than that observed in the general population. This suggests the diagnosis of club foot, especially in the face of other typically associated abnormalities of 22q11.2DS, should provoke consideration of 22q11.2DS as an underlying diagnosis, particularly in the neonatal setting.

Sidestep-induced neuromuscular miswiring causes severe locomotion defects in Drosophila larvae

Mutations in motor axon guidance molecules cause aberrant projection patterns of motor nerves. As most studies in Drosophila have analysed these molecules in fixed embryos, the consequences for larval locomotion are entirely unexplored. Here, we took advantage of sidestep (side)-mutant larvae that display severe locomotion defects because of irreparable innervation errors. Mutations in side affected all motor nerve branches and all body wall regions. Innervation defects were non-stereotypical, showing unique innervation patterns in each hemisegment. Premature activation of Side in muscle precursors abrogated dorsal migration of motor nerves, resulting in larvae with a complete loss of neuromuscular junctions on dorsal-most muscles. High-speed videography showed that these larvae failed to maintain substrate contact and inappropriately raised both head and tail segments above the substrate, resulting in unique ‘arching’ and ‘lifting’ phenotypes. These results show that guidance errors in side mutants are maintained throughout larval life and are asymmetrical with respect to the bilateral body axis. Together with similar findings in mice, this study also suggests that miswiring could be an underlying cause of inherited movement disorders.

The etiology of idiopathic congenital talipes equinovarus: a systematic review

Background

Also known as clubfoot, idiopathic congenital talipes equinovarus (ICTEV) is the most common pediatric deformity and occurs in 1 in every 1000 live births. Even though it has been widely researched, the etiology of ICTEV remains poorly understood and is often described as being based on a multifactorial genesis. Genetic and environmental factors seem to have a major role in the development of this disease. Thus, the aim of this review is to analyze the available literature to document the current evidence on ICTEV etiology.

Methods

The literature on ICTEV etiology was systematically reviewed using the following inclusion criteria: studies of any level of evidence, reporting clinical or preclinical results, published in the last 20 years (1998–2018), and dealing with the etiology of ICTEV.

Results

A total of 48 articles were included. ICTEV etiology is still controversial. Several hypotheses have been researched, but none of them are decisive. Emerging evidence suggests a role of several pathways and gene families associated with limb development (HOX family; PITX1-TBX4), the apoptotic pathway (caspases), and muscle contractile protein (troponin and tropomyosin), but a major candidate gene has still not been identified. Strong recent evidence emerging from twin studies confirmed major roles of genetics and the environment in the disease pathogenesis.

Conclusions

The available literature on the etiology of ICTEV presents major limitations in terms of great heterogeneity and a lack of high-profile studies. Although many studies focus on the genetic background of the disease, there is lack of consensus on one or multiple targets. Genetics and smoking seem to be strongly associated with ICTEV etiology, but more studies are needed to understand the complex and multifactorial genesis of this common congenital lower-limb disease.

The developmental and genetic basis of 'clubfoot' in the peroneal muscular atrophy mutant mouse

Genetic factors underlying the human limb abnormality congenital talipes equinovarus ('clubfoot') remain incompletely understood. The spontaneous autosomal recessive mouse 'peroneal muscular atrophy' mutant (PMA) is a faithful morphological model of human clubfoot. In PMA mice, the dorsal (peroneal) branches of the sciatic nerves are absent. In this study, the primary developmental defect was identified as a reduced growth of sciatic nerve lateral motor column (LMC) neurons leading to failure to project to dorsal (peroneal) lower limb muscle blocks. The pma mutation was mapped and a candidate gene encoding LIM-domain kinase 1 (Limk1) identified, which is upregulated in mutant lateral LMC motor neurons. Genetic and molecular analyses showed that the mutation acts in the EphA4-Limk1-Cfl1/cofilin-actin pathway to modulate growth cone extension/collapse. In the chicken, both experimental upregulation of Limk1 by electroporation and pharmacological inhibition of actin turnover led to defects in hindlimb spinal motor neuron growth and pathfinding, and mimicked the clubfoot phenotype. The data support a neuromuscular aetiology for clubfoot and provide a mechanistic framework to understand clubfoot in humans.