Genetic Overview of Syndactyly and Polydactyly

Characterizing the Timing of Surgical Repair of Congenital Hand Differences in the United States

Background: Suggested timing of reconstruction of congenital hand differences varies widely. The goal of timely intervention is to achieve near-normal appearance and function. We evaluated national trends in surgical timing of congenital hand differences to determine whether interventions align with the literature. Methods: Recommended ages for surgical reconstruction were identified. The Pediatric National Surgical Quality Improvement Project database was queried from 2012 to 2020 for children who underwent surgery for simple syndactyly (SS), complex syndactyly (CS), polydactyly, or congenital trigger finger. Subgroup analysis was conducted to assess whether the surgeon's subspecialty (plastic surgery vs orthopedic surgery, pediatric vs generalist) influenced the timing of repair. Results: Congenital trigger finger and CS reconstructions occurred largely within the recommended age range (73.8% and 52.2%, respectively). Polydactyly repairs primarily occurred earlier than the recommendations (54.0%). Timing of SS reconstruction was split, either occurring before (44.3%) or after (41.4%) the recommendations. For children with polydactyly, plastic surgeons were more likely to perform polydactyly reconstruction at a younger age compared with orthopedic surgeons (P = .0001). Conclusions: Established expert recommendations for the treatment of congenital hand differences are largely not followed in practice in the United States. This suggests that practice patterns may not be determined by the surgical literature.

A novel missense variant located within the zinc finger domain of the GLI3 gene was identified in a Vietnamese pedigree with index finger polydactyly

BACKGROUND

Polydactyly, particularly of the index finger, remains an intriguing anomaly for which no specific gene or locus has been definitively linked to this phenotype. In this study, we conducted an investigation of a three-generation family displaying index finger polydactyly.

METHODS

Exome sequencing was conducted on the patient, with a filtration to identify potential causal variation. Validation of the obtained variant was conducted by Sanger sequencing, encompassing all family members.

RESULTS

Exome analysis uncovered a novel heterozygous missense variant (c.1482A>T; p.Gln494His) at the zinc finger DNA-binding domain of the GLI3 protein within the proband and all affected family members. Remarkably, the variant was absent in unaffected individuals within the pedigree, underscoring its association with the polydactyly phenotype. Computational analyses revealed that GLI3 p.Gln494His impacts a residue that is highly conserved across species.

CONCLUSION

The GLI3 zinc finger DNA-binding region is an essential part of the Sonic hedgehog signaling pathway, orchestrating crucial aspects of embryonic development through the regulation of target gene expression. This novel finding not only contributes valuable insights into the molecular pathways governing polydactyly during embryonic development but also has the potential to enhance diagnostic and screening capabilities for this condition in clinical settings.

Postaxial polydactyly of the bilateral hand in toddler: Case report and literature review

Polydactyly is a common congenital malformation of the hand and foot characterized by an extra digit or duplication of digits. Polydactyly can present as preaxial, complex, or postaxial types. It has various presentations, and it can be an isolated anomaly or part of other diseases or syndromic conditions. Incidences are more common in European and Asian descent. The first line of treatment commonly practiced is surgery to create an aesthetically normal functioning hand. In this report, we present a case of bilateral hand polydactyly in a 2-year 6-month-old boy of Asian descent. No other abnormalities or malformations were observed elsewhere in his body. He is otherwise a healthy boy with no family history of malformations. The pattern is not consistent with any syndromic disease. He subsequently underwent surgical resection of the extra digits and a follow-up review showed normal function of the hands without contracture and other complications of the surgical site.

Chronic Overlapping Pain Conditions and Nociplastic Pain

Chronic Overlapping Pain Conditions (COPCs) are a subset of chronic pain conditions commonly comorbid with one another and more prevalent in women and assigned female at birth (AFAB) individuals. Pain experience in these conditions may better fit with a new mechanistic pain descriptor, nociplastic pain, and nociplastic type pain may represent a shared underlying factor among COPCs. We applied GenomicSEM common-factor genome wide association study (GWAS) and multivariate transcriptome-wide association (TWAS) analyses to existing GWAS output for six COPCs in order to find genetic variation associated with nociplastic type pain, followed by genetic correlation (linkage-disequilibrium score regression), gene-set and tissue enrichment analyses. We found 24 independent single nucleotide polymorphisms (SNPs), and 127 unique genes significantly associated with nociplastic type pain, and showed nociplastic type pain to be a polygenic trait with significant SNP-heritability. We found significant genetic overlap between multisite chronic pain and nociplastic type pain, and to a smaller extent with rheumatoid arthritis and a neuropathic pain phenotype. Tissue enrichment analyses highlighted cardiac and thyroid tissue, and gene set enrichment analyses emphasized potential shared mechanisms in cognitive, personality, and metabolic traits and nociplastic type pain along with distinct pathology in migraine and headache. We use a well-powered network approach to investigate nociplastic type pain using existing COPC GWAS output, and show nociplastic type pain to be a complex, heritable trait, in addition to contributing to understanding of potential mechanisms in development of nociplastic pain.

Sequence Variants in MEGF8 and GJA1 Underlying Syndactyly

Introduction

Syndactyly is a common congenital limb malformation. It occurs due to embryological failure of digit separation during limb development. Syndactyly often runs in families with an incidence of about one out of every 2,500-3,000 live births.

Methods

Here, we have reported two families presenting features of severe forms of syndactyly. The disorder segregated in autosomal recessive in one and in autosomal dominant manner in the second family. Search for the causative variants was carried out using whole-exome sequencing in family A and candidate gene sequencing in family B.

Results

Analysis of the sequencing data revealed two novel missense variants, including p.(Cys1925Arg) in MEGF8 in family A and p.(Thr89Ile) in GJA1 in family B.

Conclusion

In conclusion, the novel findings, presented here, not only expand the mutation spectrum in the genes MEGF8 and GJA1, but this will also facilitate screening other families carrying similar clinical features in the Pakistani population.

The changing epidemiology of syndactyly in Chinese newborns: a nationwide surveillance-based study

BACKGROUND

Little is known about the epidemiologic features of syndactyly (SD) in Chinese newborns.

METHODS

Using 2007-2019 data from the Chinese Birth Defects Monitoring Network, we conducted a prevalence analysis on overall, isolated and associated syndactyly according to birth year, maternal age, maternal residence, geographic region and infant sex, with special interests in time trends, perinatal outcomes and clinical phenotypes.

RESULTS

A total of 13,611 SD cases were identified among 24,157,719 births in the study period, yielding the prevalence of 5.63, 4.66 and 0.97 per 10,000 for overall, isolated, and associated SD, respectively. The prevalence of each type of SD exhibited an upward trend over the period. The prevalence of overall SD varied significantly by maternal residence (urban vs. rural, 6.69/10,000 vs. 4.35/10,000), maternal age (< 20 years, 5.43/10,000; 20-24 years, 5.03/10,000; 25-29 year, 5.65/10,000; 30-34 years, 6.07/10,000; ≥ 35 years, 5.76/10,000), geographic region (central, 5.07/10,000; east, 6.75/10,000; west, 5.12/10,000), and infant sex (male vs. female, 6.28/10,000 vs. 4.86/10,000). Newborns with associated SD were more likely to be born prematurely (29.2% vs. 10.6%) or with low birthweight (30.5% vs.9.8%) than those with isolated SD. The bilaterally, and unilaterally affected cases accounted for 18.4% and 76.7%, respectively. The feet were more frequently involved (64.3%) in those bilaterally affected cases, while right side preference (right vs left: 53.8% vs 46.2%) and upper limbs preference (hand vs foot: 50.8% vs 48.0%) were found in unilateral cases.

CONCLUSIONS

The prevalence of syndactyly in China is on the rise and notably higher than that in other Asian and European countries, highlighting the importance of investigating the etiology, epidemiology, and clinical implications of this condition in the Chinese population.

Keeping you on your toes: Smith-Lemli-Opitz Syndrome is an easily missed cause of developmental delays

Smith-Lemli-Opitz syndrome (SLOS) is a relatively common genetic cause of developmental delay and may only present in conjunction with 2,3 toe syndactyly. This case series illustrates a milder phenotype of SLOS, where the predominant findings are neurocognitive in the presence of 2,3 toe syndactyly.

An unusual manifestation of asymmetric polydactyly of both feet and symmetrical polydactyly of both hands

In the routine treatment at the hospital, it was observed that a 31-year-old Asian woman developed foot pain after work, with clinical manifestations including local tenderness, abrasion, and a rare case of polydactyly with bilateral foot asymmetry. In addition, we also found that the patient had two-handed symmetric polydactyly. According to our observations, there seem to be few similar cases reported in the past of a two-handed symmetric polydactyly combined with a feet asymmetry polydactyly in the same person, so this is a relatively rare reported case of polydactyly. This paper aims to present detailed case report and discuss related diseases in a morphological and clinical study.

Identification of a HOXD13 variant in a Mongolian family with incomplete penetrance syndactyly by exon sequencing

Background

Syndactyly (SD) refers to a deformity caused by the fusion and limb differentiation disorder of soft tissues and/or skeletons to varying extents between adjacent fingers (toes). The main features of this disease are phenotypic heterogeneity and genetic heterogeneity. In this study, we examined four generations of a Chinese Mongolian with different phenotypes of syndactylia and analysed and identified the pathogenic genetic variants of SD by exon sequencing.

Methods

The clinical phenotypes of patients were analysed, and the hands and feet were examined by X-ray. The pedigree was drawn, and the family data were analysed. Peripheral blood was collected from the family members, and genomic DNA was extracted. The candidate genes of SD were identified by exon sequencing, and the mutation sites of the captured candidate genes were amplified by PCR and verified by Sanger sequencing.

Results

The family has congenital syndactyly, which is an autosomal dominant disease. At present, this condition has been passed down for 4 generations and was identified in 9 patients, including 4 males and 5 females. Five patients, I₂, II₄, III₅, III_,7 and III₁₀, had unilateral syndactyly, and four patients, III₁₆, IV₃, IV₆ and IV₇, had bilateral finger syndactyly. All of their toes were unaffected. The proband and the other patients in this family had a c.917G > A (p.R306Q) mutation, which is located at position 917 of the second exon of the HOXD13 gene. This mutation results in a change in the amino acid at position 306, in which arginine is changed to glutamine. This mutation cosegregates in unaffected individuals and affected patients in this family. Moreover, 201 Mongolian genome databases and a thousand human genome databases were referenced to further confirm that the pathogenic genetic variant that causes syndactyly in this family is found in HOXD13.

Conclusion

This study found that the mutation site of the pathogenic gene in this family was HOXD13, c.917G > A (p.R306Q). The phenotype of the family member III₁₂ was normal, but this member was also a carrier of the pathogenic genetic variant. This indicates that the disease of this family has incomplete penetrance characteristics. Our results further enrich the expression profile of the HOXD13 gene.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01360-3.

Preaxial Polydactyly in an Elderly Woman

A 70-year-old woman born and raised in India presented with Wassel type IV preaxial polydactyly of the right thumb and difficulty performing daily activities. She elected for surgical reconstruction after postponing the procedure for many years due to cultural norms. Her postoperative course was unremarkable. At her 3-month follow-up, she was diagnosed with carpal tunnel syndrome and underwent open carpal tunnel release. Preaxial polydactyly repair is unusual in patients older than 25 years. Though the duplication is considered lucky in South Asia, indications for this case were arthritic pain, cosmesis, and function. This case report details a unique indication for polydactyly reconstruction, arthritic pain, which may benefit hand surgeons when discussing the literature on adult polydactyly with their patients.

A 12-Day-Old Female with Hypothermia, Hypoglycemia and Hyperbilirubinemia

A 12-day-old, full-term female, born small for gestational age, presented to the emergency department with a 1-week history of worsening hyperbilirubinemia, intermittent hypoglycemia, and episodic hypothermia. The baby's emergency department evaluation revealed transaminitis, pneumatosis intestinalis, indirect hyperbilirubinemia, and hypoglycemia. She was admitted to the ICU and received intravenous glucose, bowel rest, and phototherapy. Thyroid-stimulating hormone, thyroxine, and cortisol levels were low, and growth hormone was undetectable. The patient was hospitalized for a total of 19 days and was discharged from the hospital.

Bone deformities in patients with neurofibromatosis type 1: Single-center experience

BACKGROUND

Neurofibromatosis type 1 (NF-1) is the most common neurocutaneous syndrome with an autosomal dominant inheritance. However, half of the cases are de novo mutations. Involvement of bone, skin (cafe au lait macules), as well as ocular and tumoral formations is also associated with NF-1. Here, we present our case series of patients with bone deformities.

METHODS

The medical files of patients with NF-1 who were followed up by the same doctor in the pediatric neurology outpatient clinic over 2 years were retrospectively analyzed.

RESULTS

Overall, 19 girls and 13 boys were diagnosed with NF-1. Of these 32 patients, 12 (nine girls, three boys) were found to have bone pathologies. The average age was of these patients with bone pathology was 7.5 and 9.5 years. Scoliosis, bowing, short stature, and long bone cysts were found in descending order of frequency. Severe adhesions in the hands and feet as well as phalangeal hypoplasia were noted in one patient.

CONCLUSION

NF-1 requires a multidisciplinary approach. Routine follow-up is very important as it is known that deformities that affect different systems may appear or increase with age. Severe hand and foot anomalies seen in one of our patients did not seem to be associated with NF-1.

Case report: Bilateral simple Syndactyly in a toddler with maternal exposure to cabergoline

Cabergoline is routinely prescribed in the management of prolactin excreting adenomas and is associated with low risk of congenital malformations and teratogenicity. Here, we reported the case of a bilateral simple syndactyly in a toddler with maternal exposure to cabergoline during the pregnancy. This association has not been previously described before.

Pediatric Forefoot Deformities

This article explores different pediatric forefoot deformities including syndactyly, polydactyly, macrodactyly, curly toe, and congenital hallux varus. The epidemiology and genetic background are reviewed for each condition. Preferred treatment options and recommended surgical techniques are discussed with review of the current literature.

An extremely rare case of bonneau syndrome with novel cardiac and eye manifestations

Bonneau or cardio-ducto-polysyndactyly syndrome is an extremely rare, life-threatening developmental defect, which has only been reported in eight patients previously. Here, we describe one such case of Bonneau syndrome in a newborn with additional novel manifestations. This late preterm (35 weeks of gestation) neonate born to parents of consanguineous marriage following a pregnancy complicated by polyhydramnios was symmetrically small for date at birth (<3^rd centile for weight, length, and occipitofrontal circumference). She had the typical Bonneau syndrome features such as facial dysmorphism and polysyndactyly in addition to novel eye manifestations (microphthalmia, cataract, and vitreous hemorrhage) and cardiac defects such as D-transposition of the great arteries and pulmonary valve stenosis. The chromosomal study was normal (46, XX). The multiple congenital anomalies made the cardiac defects inoperable, and the patient died at the age of 16 days due to uncontrolled cardiac failure. A very high index of suspicion is required by pediatricians/neonatologists to identify this very rare syndrome based on presentation with known features.

Pediatric Office Procedures

Pediatric patients are frequently evaluated in primary care clinics. Thus, there exists a need to understand common pediatric problems and to acquire a degree of familiarity with pediatric procedures. This article will review techniques and the current evidence for frequently performed pediatric procedures, including umbilical granuloma chemocautery, frenotomy, suture ligation of type B postaxial polydactyly, reduction of nursemaid's elbow, hair tourniquet removal, and tympanometry.

Rare phenotype: Hand preaxial polydactyly associated with LRP6-related tooth agenesis in humans

Low-density lipoprotein receptor-related protein 6 (LRP6) is a pathogenic gene of selective tooth agenesis-7 (OMIM#616724). Although the malformation of the digits and fore- and hindlimbs has been reported in Lrp6-deficient mice, it has been rarely discovered in humans with LRP6 mutations. Here, we demonstrate an unreported autosomal dominant LRP6 heterozygous mutation (c.2840 T > C;p.Met947Thr) in a tooth agenesis family with hand polydactyly, and another unreported autosomal dominant LRP6 heterozygous mutation (c.1154 G > C;p.Arg385Pro) in a non-syndromic tooth agenesis family. Bioinformatic prediction demonstrated the deleterious effects of the mutations, and LRP6 structure changes suggested the corresponding functional impairments. Analysis on the pattern of LRP6-related tooth agenesis demonstrated the maxillary lateral incisor was the most affected. Our study report that LRP6 mutation might be associated with hand preaxial polydactyly in humans, which broaden the phenotypic spectrum of LRP6-related disorders, and provide valuable information on the characteristics of LRP6-related tooth agenesis.

When Is Primary Metacarpal Corrective Osteotomy Recommended in Patients with Flatt Type IV Radial Polydactyly?

BACKGROUND

The aim of this study was to determine when primary metacarpal corrective osteotomy is recommended in patients with Flatt type IV radial polydactyly.

METHODS

A total of 78 patients with Flatt type IV radial polydactyly were included. The authors performed metacarpal osteotomy if the angulation of the metacarpophalangeal joint was not correctable by the intraoperative radial stress test. The authors measured the metacarpal deviation angle of the thumb in simple posteroanterior radiographs. The clinical outcomes were assessed using Japanese Society for Surgery of the Hand evaluation total score and the metacarpal deviation angle correction angle. These outcomes were compared between the patients who underwent metacarpal osteotomy and those who did not. Of the patients who did not undergo metacarpal osteotomy, the relationships between preoperative metacarpal deviation angle and the metacarpal deviation angle correction angle were formulated using segmented linear regression analysis.

RESULTS

There were no significant differences in the demographic features and the value of preoperative metacarpal deviation angle between the two groups. However, the metacarpal deviation angle correction angle and Japanese Society for Surgery of the Hand evaluation total score were significantly higher in the patients who underwent metacarpal osteotomy. The segmented linear regression analysis demonstrated a breakpoint, indicating that the soft-tissue procedure alone does not sufficiently correct the metacarpal deviation angle. For the postoperative metacarpal deviation angle to be 5 degrees, the preoperative metacarpal deviation angle was calculated as 10.8 degrees.

CONCLUSION

If the preoperative metacarpal deviation angle is greater than 10.8 degrees, metacarpal osteotomy can be considered even in patients with correctable metacarpophalangeal joint by intraoperative radial stress test.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Identification of the genetic basis of sporadic polydactyly in China by targeted sequencing

Purpose

Polydactyly is a highly heterogeneous group of skeletal deformities in clinical and genetic background. The variation spectrum in Chinese sporadic polydactyly has not been comprehensively analyzed. To elucidate genetic variation spectrum and genotype-phenotype correlations in Chinese patients with polydactyly, we conducted comprehensive genetic analysis of patients nationwide using targeted sequencing.

Methods

A total of 181 patients diagnosed with polydactylies were recruited. We designed a targeted capture panel for sequencing 721 genes that are associated with the pathogenesis of skeletal dysplasia. We performed rigorous variant- and gene-level filtrations to identify potentially damaging variants, followed by enrichment analysis and gene prioritization.

Results

A total of 568 deleterious variants of 293 genes were identified in 173 of 181 patients with a positive rate of 95.6% by targeted sequencing. For each sample, an average of 3.17 deleterious variants were identified. Especially, 14 pathogenic or likely pathogenic variants were identified in 10 genes in 14 patients out of the 181 patients, providing a positive molecular diagnostic rate of 7.7%.

Conclusion

Targeted sequencing analysis provides a high efficiency approach for the genetic diagnosis of polydactyly. This is the largest next generation sequencing study performed to date in patients with polydactyly and represents the genetic basis of polydactyly typically encountered in genetics clinics.

Lower extremity postaxial polydactyly: Current literature status and future avenues

BACKGROUND

Despite lower extremity polydactyly (LEP) representing the most common congenital foot anomaly with functional and psychosocial implications, the literature is devoid of comprehensive, synthesizing reviews. The purpose of the current review is to identify an evidence-based approach to guide clinical management and shed light on reported functional and esthetic outcomes for postaxial polydactyly.

METHODS

A scoping systematic review of primary clinical studies was performed. Baseline patient characteristics, diagnostic, and surgical approaches were recorded. Main outcomes included immediate postoperative pain, infections, callouses, scar cosmesis, residual deformities, and difficulty with shoe-wear or mobility. A qualitative synthesis of outcomes was performed, and a therapeutic algorithm was developed.

RESULTS

Nine primary studies were identified representing 375 cases of LEP; mean age was 28.8 months (range: 20-40.6 months), and mean follow-up: 42.7 months (range: 1 month-41 years). Ray dominance and the presence of syndactyly were identified as the most important factors for surgical planning; age at surgery was insignificant. A lateral incision approach was used in 78% of cases. Postoperative callouses occurred in 22.1% of cases, infections in 2.5%, and intermittent pain in 11.9%. Significant issues with shoe-wear or mobilization and esthetic residual deformities were reported for 0.78% and 41.2% of cases, respectively. The incidence of residual valgus was 10.6%.

CONCLUSION

LEP is most commonly managed with excision of the non-dominant ray and carries excellent long-term functional outcomes, as presented herein. Numerous techniques are discussed to minimize the risk of esthetic sequalae, although the presence of residual valgus remains a concern. A therapeutic algorithm is proposed for the optimal management of LEP.

Geographic distribution of live births and infant mortality from congenital anomalies in Brazil, 2012-2017

In the 2010-2014 period, the mean prevalence of congenital anomalies (CA) in the world was estimated at 398/10,000 births. CA are an important cause of mortality, disability, and comorbidity. Thus, the present study aims to describe the geographical and temporal distributions of live births and infant mortality (IM) due CA (IM-CA) in Brazil, from 2012 to 2017. The data used in this study is available at the Department of Informatics of the Unified Health System (DATASUS). The prevalence of CA at birth was 81.67/10,000 (95% CI 80.46-82.88), and the IM-CA rate was 27.97/10,000 (95% CI 27.95-28.00) in the studied period. The five CA with the highest rates were polydactyly (9.66/10,000, 95% CI 6.10-9.82), Down syndrome (3.40/10,000, 95% CI 3.41-5.99), microcephaly (2.92/10,000, 95% CI 2.91-3.12), hydrocephalus (2.72/10,000, 95% CI 2.65-2.90), and spina bifida (2.44/10,000, 95% CI 2.43-2.64). São Paulo was the Brazilian state with the highest CA birth rate (119.3/10,000), and Amazonas was the state with the highest IM-CA rate (33.8/10,000). The description and data analyses such as those performed in this work are relevant for healthcare systems and can be very useful in the formulation of public health campaigns and policies, as well as informing and educating professionals and the population. The management of clinical actions should consider all social, economic, geographic, and epidemiological factors.

Maternal occupational exposure to chemicals in the textile factory during pregnancy is associated with a higher risk of polydactyly in the offspring

Background: The number of children with polydactyly seen in our clinic is increasing. In addition to genetic factors, an influence of environmental effects during pregnancy is becoming increasingly apparent; however, epidemiological data on these effects are lacking.Methods: This hospital-based, case-control study enrolled 143 patients with polydactyly and 286 control patients with no genetic diseases, to evaluate the association between maternal exposure to a textile factory environment during pregnancy and the likelihood of giving birth to a child with polydactyly.Results: Maternal exposure to a textile factory environment during pregnancy was associated with an increased risk of giving birth to a child with polydactyly (exposure to textile factory environment: unadjusted odds ratio (OR) = 3.31, 95% confidence interval (CI) = 1.75-6.27, p = .0002; work seniority of exposed occupation: unadjusted OR 1.28, 95% CI = 1.13-1.47, p = .0002). Covariate screening indicated that certain risk factors (family monthly income per capita, mother's emotional state during pregnancy, colporrhagia, passive smoking, smoking, and history of consanguineous marriage) were potential confounding factors. After adjusting for these variables, the OR of exposure to a textile factory environment remained significant (exposure to textile factory environment: adjusted OR = 3.08, 95% CI = 1.32-7.19, p = .0094; work seniority of exposed occupation: adjusted OR = 1.58, 95% CI = 1.20-2.08, p = .0010). The risk of polydactyly increased with the number of years of employment.Conclusions: Maternal exposure to a textile factory environment appears to be a risk factor for polydactyly in newborns.

National Patterns in Surgical Management of Syndactyly: A Review of 956 Cases

Purpose: Being one of the most common congenital hand malformations, syndactyly is repaired by orthopedic, plastic, and fellowship-trained general surgeons. Limited multi-institutional outcomes analyses regarding incidence, timing, and type of repair exist. Methods: All syndactyly cases performed over a 5-year period from 2012-2016 were isolated from the National Surgical Quality Improvement Program Pediatric database. Patient demographics, surgical factors, perioperative outcomes, and risk factors were analyzed using χ², Fisher exact, and t-test analysis. Results: A total of 956 patients who underwent syndactyly repair were identified. Most cases were simple syndactyly with nearly even case distribution among plastic and orthopedic surgeons. Most patients were men and Caucasian. Mean age at the time of surgery was 2.6 years. Most cases were performed as outpatient surgery. Patients of plastic surgeons had significantly more airway abnormalities and shorter operative times. Patients with complex syndactyly had significantly more ventilator dependence, tracheostomy, and comorbidities when compared with those with simple syndactyly. Cases with complex syndactyly also had longer operative times and a higher rate of superficial surgical site infections. Conclusions: Syndactyly repair is a safe procedure with few major or minor reconstructive complications regardless of the surgical specialty or syndactyly type. Patients with complex syndactyly have significantly more preoperative comorbidities with comparable outcomes. orthopedic surgeons have significantly longer operative times than plastic surgeons, likely due to caring for increased number of patients with complex syndactyly.

Association between maternal exposure to PM10 and polydactyly and syndactyly: A population-based case-control study in Liaoning province, China

BACKGROUND

The number of studies on air pollution with birth defects as the primary outcome has increased dramatically over the past two decades, but the potential role of specific air pollutants in congenital limb anomalies remains unclear.

OBJECTIVES

To evaluate associations between preconception and first-trimester PM₁₀ exposure and polydactyly and syndactyly in a population-based case-control study.

METHODS

Polydactyly cases (n = 2605), syndactyly cases (n = 595), and controls without any birth defects (n = 7950) born between 2010 and 2015 were selected from the Maternal and Child Health Certificate Registry of Liaoning Province. The monthly mean PM₁₀ concentrations were obtained from 75 air monitoring stations, and the exposure assessment was based on the mean concentration of all stations in mother's residential city. A multivariable logistic regression model was constructed to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

PM₁₀ exposure was positively associated with the risks of polydactyly (preconception: aOR_{T3 vs. T1} = 1.95, 95% CI 1.56-2.45, aOR = 1.06, 95% CI 1.01-1.10 [per 10-μg/m³ increment]; first-trimester: aOR_{T3 vs. T1} = 2.51, 95% CI 2.00-3.15) and syndactyly (preconception: aOR_{T3 vs. T1} = 2.86, 95% CI 1.98-4.13, aOR = 1.11, 95% CI 1.03-1.20 [per 10-μg/m³ increment]; first-trimester: aOR_{T3 vs. T1} = 3.10, 95% CI 2.11-4.56). Analyses based on single month exposure windows basically showed similar positive associations. Additionally, these findings were robust in sensitivity analyses and broadly consistent across subgroups.

CONCLUSION

Our study suggest that preconception and first-trimester PM₁₀ exposures are related to increased risks of polydactyly and syndactyly.

Identification of novel missense mutations associated with non-syndromic syndactyly in two vietnamese trios by whole exome sequencing

BACKGROUND AND METHODS

Syndactyly is a congenital disorder caused by an irregularity in limb formation during the embryonic development. Many studies have demonstrated the critical effect of genetic factor in controlling the outcome of non-syndromic syndactyly. However the signaling pathway causing this disease has not been fully understood. The aim of this study was to identify the genetic mutations that related to syndactyly type I-c and I-d by exome sequencing.

RESULTS

The exome sequence from two patients revealed two novel heterozygous missense mutations: GLI3: cG1622A pT541M and GJA1: cT274C p.Y92H. Sanger sequencing result confirmed that these mutations were present under heterozygous form in the affected mothers, but not in the unaffected fathers. In-silico analyses by SIFT, Polyphen-2, PredictSNP, PhD-SNP, and PROVEAN did confirm the damaging effect of these mutations in the structure and function of the proteins.

CONCLUSIONS

The result suggested that the two novel mutations may be pathogenic for the disease in these families under the dominant model, provided the initial data for further functional studies to investigate whether those mutations play a disturbing role in the molecular network of syndactyly.

Treatment of congenital syndactyly

Defined as the union of two adjacent digits, syndactyly is one of the most common congenital deformities. The severity of the malformation depends on the fusion level, the tissues involved in the union, and whether it is isolated or syndromic. In order to improve the hand's appearance and function, surgery is recommended in the great majority of cases, ideally during early childhood (i.e., before entering school). Web space reconstruction is done using local flaps. Depending on the flap design, digital resurfacing can be done with or without skin grafts. While graftless techniques have shorter operating times and no morbidity associated with skin harvesting, their cosmetic outcomes seem to be worse than those of traditional grafting techniques, with more postoperative complications; furthermore, such techniques cannot be used in all cases, especially those with osteoarticular fusions. When the fingertip is involved, paronychial reconstruction is carried out with pulp flaps. The prognosis for these deformities directly depends on their severity, with excellent outcomes in cases of cutaneous fusion, and much less predictable ones when osteoarticular and/or tendinous tissues are involved.

Isolated hexadactylia: A rare case of central polydactyly of the foot

BACKGROUND

Central polydactyly of foot is uncommon form of polydactyly but it usually causes intermetatarsal widening because of metatarsal bifurcation. Central polydactyly associated with T shaped bifurcation of metatarsal in vertical plane has not been reported yet.

CASE

We present a 4 year male child with extra toe on the dorsal aspect of right foot with complains of difficulty in wearing footwear and poor cosmesis. The extra digit was fully developed with bifurcation of 2^nd metatarsal bone proximal to the head without any intermetatarsal widening. The angular deviation was 45° to the longitudinal axis of foot and in a plane vertical to the transverse arch of foot. The child was operated with excision of extra toe without any residual bony deformity.

CONCLUSION

The central polydactyly is rare type of polydactyly of foot. Central polydactyly with metatarsal extension causing intermetatarsal widening has been well described entity. But the previous classifications need to be modified to include central polydactyly with vertical oriented T bifurcation of metatarsal bone without intermetatarsal widening.

Sub-Exome Target Sequencing in a Family With Syndactyly Type IV Due to a Novel Partial Duplication of the LMBR1 Gene: First Case Report in Fujian Province of China

Syndactyly is one of the most frequent hereditary limb malformations with clinical and genetical complexity. Autosomal dominant syndactyly type IV (SD4) is a rare form of syndactyly, caused by heterozygous mutations in a sonic hedgehog (SHH) regulatory element (ZRS) which resides in intron 5 of the LMBR1 gene on chromosome 7q36.3. SD4 is characterized by complete cutaneous syndactyly of the fingers, accompanied by cup-shaped hands due to flexion of the fingers and polydactyly. Here, for the first time, we reported a large Chinese family from Fujian province, manifesting cup-shaped hands consistent with SD4 and intrafamilial heterogeneity in clinical phenotype of tibial and fibulal shortening, triphalangeal thumb-polysyndactyly syndrome (TPTPS). We identified a novel duplication of ∼222 kb covering exons 2–17 of the LMBR1 gene in this family by sub-exome target sequencing. This case expands our new clinical understanding of SD4 phenotype and again confirms the feasibility to detect copy number variation by sub-exome target sequencing.

Debutant iOS app and gene-disease complexities in clinical genomics and precision medicine

Background

The last decade has seen a dramatic increase in the availability of scientific data, where human-related biological databases have grown not only in count but also in volume, posing unprecedented challenges in data storage, processing, analysis, exchange, and curation. Next generation sequencing (NGS) advancements have facilitated and accelerated the process of identifying genetic variations. Adopting NGS with Whole-Genome and RNA sequencing in a diagnostic context has the potential to improve disease-risk detection in support of precision medicine and drug discovery. Several bioinformatics pipelines have been developed to strengthen variant interpretation by efficiently processing and analyzing sequence data, whereas many published results show how genomics data can be proactively incorporated into medical practices and improve utilization of clinical information. To utilize the wealth of genomics and health, there is a crucial need to generate appropriate gene-disease annotation repositories accessed through modern technology.

Results

Our focus here is to create a comprehensive database with mobile access to actionable genes and classified diseases, considered the foundation for clinical genomics and precision medicine. We present a publicly available iOS app, PAS-Gen, which invites global users to freely download it on iPhone and iPad devices, quickly adopt its easy to use interface, and search for genes and related diseases. PAS-Gen was developed using Swift, XCODE, and PHP scripting that uses Web and MySQL database servers, which includes over 59,000 protein-coding and non-coding genes, and over 90,000 classified gene-disease associations. PAS-Gen is founded on the clinical and scientific premise that easier healthcare and genomics data sharing will accelerate future medical discoveries.

Conclusions

We present a cutting-edge gene-disease database with a smart phone application, integrating information on classified diseases and related genes. The PAS-Gen app will assist researchers, medical practitioners, and pharmacists by providing a broad and view of genes that may be implicated in the likelihood of developing certain diseases. This tool with accelerate users’ abilities to understand the genetic basis of human complex diseases and by assimilating genomic and phenotypic data will support future work to identify gene-specific designer drugs, target precise molecular fingerprints for tumors, suggest appropriate drug therapies, predict individual susceptibility to disease, and diagnose and treat rare illnesses.

Hemihyperplasia/hemihypertrophy in adolescents: prospective international study

AIM

The reported incidence of isolated hemihyperplasia (IH) has a very wide range (from 1:13,000 to 1:86,000 live births) and further clarification is needed. We hypothesized that a survey of the birth prevalence of IH among newborn infants may underestimate the incidence of IH by overlooking late-onset cases.

METHODS

The prospective international multicenter study utilized the two-steps selection tool for an anonymous survey of volunteers of 15-18 years old. The initial step was "three measurements-three questions" screening, or "face-palms-calves survey". The subsequent step was an in-depth assessment of selected cases to exclude localized, lesional and syndrome-related cases as well as body asymmetry within normative range and to select suspected cases of IH. This step included measurements of various anatomical regions and a subsequent questionnaire. The participants that were selected in a risk group were advised to refer to medical institutions for clinical, genetic and instrumental investigation.

RESULTS

Out of 6000 of selected participants (male, M 3452, female, F 2548), 229 (3.82%) were selected for detailed investigation and 57 (0.95%) were assigned to the risk group. Only 36 of them were actually referred to medical institutions and in two cases the diagnosis of IH was confirmed.

CONCLUSION

Our survey indicated the prevalence of IH at the age of adolescence as approximately 1:3000. While IH is a hereditary genetic disorder, it may not be detected in newborns and infants and the true prevalence of the disease can be estimated if older age children are screened.

Thumb duplication: molecular analysis of different clinical types

PURPOSE

Molecular analysis of different types of thumb duplication and identification of new suspected gene mutations.

MATERIALS AND METHODS

In a series of patients operated for polydactyly, DNA was extracted from blood samples collected preoperatively. Among these, the samples of two patients with thumb duplication (Wassel types III and IV) were initially selected for molecular analysis. The method of Clinical Exome Solution was used for the study of the phenotype-involved genes. Next-generation sequencing (NGS) was performed on a NextSeq-500 Platform (Illumina), and Sophia DDM^® SaaS algorithms were used for the bioinformatics analysis of the data.

RESULTS

In total, 8-including 4 new-mutations were detected in CEP290 (1 mutation), RPGRIP1 (2 mutations), TMEM216 (2 mutations), FBN1 (1 mutation), CEP164 (1 mutation), and MEGF8 (1 mutation) genes. NGS revealed 3 mutated genes in the patient with Wassel III thumb duplication and 5 mutated genes in the patient with Wassel IV duplication. The molecular analysis revealed that the patients had 2 mutated genes in common, but they only shared one common mutation.

CONCLUSION

The new detected mutations are most probably associated with thumb duplication, as they belong to genes with already described mutations causing ciliopathies, often including polydactyly in their phenotype. Recognition of these mutations will be helpful to prenatal diagnosis, operative treatment strategy prediction, and possible future experimental applications in gene therapy.

Role of GLI Transcription Factors in Pathogenesis and Their Potential as New Therapeutic Targets

GLI transcription factors have important roles in intracellular signaling cascade, acting as the main mediators of the HH-GLI signaling pathway. This is one of the major developmental pathways, regulated both canonically and non-canonically. Deregulation of the pathway during development leads to a number of developmental malformations, depending on the deregulated pathway component. The HH-GLI pathway is mostly inactive in the adult organism but retains its function in stem cells. Aberrant activation in adult cells leads to carcinogenesis through overactivation of several tightly regulated cellular processes such as proliferation, angiogenesis, EMT. Targeting GLI transcription factors has recently become a major focus of potential therapeutic protocols.