Whole genome resequencing reveals candidate genes for postaxial polydactyly in Large White pigs.

Polydactyly is a genetic abnormality that affects both pig welfare and industry profits. Despite efforts to explore the genetic basis of pig polydactyly, progress remains limited. In this study, we analyzed a group of Large White pigs with postaxial polydactyly, including 29 cases and 79 controls from 24 families. High-depth sequencing was performed on 20 pigs, while low-depth sequencing was improved through imputation for the remaining pigs. A genome-wide association study (GWAS) and genetic differentiation were conducted using the resequencing dataset, resulting in the identification of 48 significantly associated SNPs and 27 candidate regions. The genetic differentiation regions on chromosomes 5 and 18, which harbored GWAS-identified SNPs, were delineated as confidence regions. The confidence region at Chr18: 1.850-1.925 Mb covers the fifth intron of LMBR1, a gene that contains an important regulatory element for SHH, known as ZRS. Mutations in this ZRS have been found to cause polydactyly in animals and humans. Therefore, we propose LMBR1 as a prospective candidate gene for postaxial polydactyly. These findings emphasize the importance of exploring the role of ZRS within LMBR1 in the pathogenesis of polydactyly in pigs.

Morphologic Changes in Postaxial Polydactyly of the Foot: A Standardized Quantitative Analysis Using the Watanabe-Fujita Classification.

BACKGROUND: Postaxial polydactyly of the foot is one of the most common congenital abnormalities. A wide forefoot, short toe, and lateral joint deviation are associated with aesthetic and functional outcomes. This study used the Watanabe-Fujita classification to characterize the preoperative and postoperative skeletal morphology of postaxial polydactyly of the foot. METHODS: This retrospective study included 42 patients (51 feet) with postaxial polydactyly treated at age 1 year. Radiographs taken at ages 0 and 3 to 4 years were used for morphologic analysis. The length of the reconstructed toe, the distance between the fourth and fifth metatarsals, and joint deviation angles were measured. The length measures were standardized using the length of the third metatarsal. Morphologic characteristics were compared based on the Watanabe-Fujita classification at ages 0 and 3 to 4 years. Long-term outcomes were also evaluated in patients followed up for longer than 6 years. RESULTS: The fifth-ray proximal phalangeal subtype had the shortest toe length both at ages 0 and 3 to 4 years. Proximal phalangeal joint lateral deviation improved postoperatively in 78% of patients with the fifth-ray middle phalangeal subtype, regardless of reconstruction type. There was no significant change in proximal phalangeal joint deviation between ages 3 to 4 years and 7 years or older. A residual metatarsal was associated with lateral metatarsophalangeal joint deviation and a wide intermetatarsal distance, and required revision surgery. CONCLUSIONS: Morphologic changes of postaxial polydactyly of the foot were successfully characterized using the Watanabe-Fujita classification. This classification could be useful for planning surgical strategies and anticipating morphologic outcomes. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Surgical Excision of Postaxial Polydactyly Type B in the Office Setting.

BACKGROUND: Simple postaxial polydactyly (type B) is a common congenital hand malformation often treated by suture or clip ligation. METHODS: We present a case series of patients with simple postaxial polydactyly treated by surgical excision using local anesthesia in an office setting. RESULTS: The procedure was performed on 78 digits in 48 children with a mean age of 10.2 weeks. There were no intraoperative or early postoperative complications. A follow-up by phone interview was performed at an average of 3.2 years postoperatively. All patients were reported to be pain-free and have normal function without a perceived range of motion deficits. All parents selected the highest level of satisfaction regarding cosmetic outcomes and overall experience with the procedure. CONCLUSIONS: These results demonstrate that an office-based surgical excision is a safe, effective, and economical treatment option and has developed into our standard of care for this common condition.

Central polydactyly of the foot: An experience of a treatment of 22 patients.

BACKGROUND: The central polydactyly of the foot is a rare congenital disorder, and its characteristics are not well known. This study aims to investigate its disease concept. METHODS: We obtained the medical records of patients who were treated surgically for central polydactyly of the foot at our hospital during a 32-year period from 1990 to 2021 retrospectively. We compared our clinical data with other case series reports to investigate the characteristics of this disorder further. RESULTS: There were 22 patients (13 males and 9 females) included in our case series. Unilateral and bilateral involvements were observed in 19 (right side: 6 patients; left side: 13 patients) and 3 patients, respectively. The second toe is the commonest duplicated toe (observed in 19 toes). 19 patients had distally duplicated toes (with normal metatarsal bone). Proximally duplicated toes were observed in only two patients. CONCLUSIONS: The incidence of central polydactyly of the foot is almost equal among male and female, and bilateral involvements are few. As this abnormality is rarely reported, further investigations are needed to clarify the clinical presentation of central polydactyly of the foot.

Clinical and genetic approach in the characterization of newborns with anorectal malformation.

OBJECTIVE: This study aimed to investigate clinical, surgical, and genetic data of neonates with anorectal malformation (ARM). STUDY DESIGN: A retrospective observational study was conducted on neonates with ARM as an isolated type (group 1), with ≤2 (group 2), and with ≥3 associated malformations (group 3), born between 2009 and 2020. Distribution of ARM, associated abnormalities and genetic testing were analyzed, and risk factors for adverse outcomes were identified. RESULTS: The 45 ARM cases (36% females) were divided as follows: 13 neonates belonging to group 1 (29%), 8 to group 2 (18%), and 24 to group 3 (53%). Cases were equally distributed over 11 years. Krickenbeck anatomy was: without fistula/imperforate anus (18%), perineal fistula (36%), rectourethral fistula (4%), rectovesical fistula (2%), vestibular fistula (4%), cloaca (4%), and rare ARMs (31%). Groups showed differences in anthropometric data, Krickenbeck anatomy, and intensive care burden. Additional major congenital abnormalities were prevalent specific of VATER/VACTERL spectrum (vertebral/anorectal/cardiac/tracheoesophageal/renal/limb defects), but also Hirschsprung disease was found in 3/20 biopsies (15%). The most frequent minor abnormality was a single umbilical artery. In group 3, we identified four de novo microdeletions at 8p23.2, 8q13.3, Xp22.31-p22.2, Xq28, four de novo microduplications at 1p36.32, 6p24.1-p23, 13q14.11, 15q11.2, one microdeletion at 9q33.1 inherited from the affected mother, one microdeletion at 7q35 inherited from the unaffected father, one structurally uncharacterized rearrangement involving 9p23-q34.3. Thus, we attributed the Xq28 deletion with inactivated FAM58A gene in one girl to the X-linked dominant STAR syndrome (toe syndactyly-telecanthus-anogenital/renal malformations). CONCLUSIONS: Despite the great physical and social burden on ARM patients and their parents, in the majority of cases, the etiology is largely unknown and attributed to be multifactorial. In females, STAR syndrome should be part of the differential diagnosis. Associated malformations of other organ systems interact in outcome parameters.

Hypothesis: Symbrachydactyly.

The term symbrachydactyly has been used for the phenotype of two or three short fingers or toes, hypoplasia of the middle and distal phalanges and variable syndactyly of the affected digits. Some clinicians have extended this diagnosis to include other phenotypes, specifically cleft hand, terminal transverse limb defects, hypoplasia of the thumb and fifth finger with nubbins for fingers 2, 3, and 4 and the hand deformity of the Poland anomaly. A malformations surveillance program can identify enough affected infants to characterize a phenotype. In the Active Malformations Surveillance Program in Boston (1972-2012) among 289,365 births, all infants and fetuses with structural abnormalities were identified from reading the examination findings by the pediatricians and pathologists and the results of diagnostic tests. Liveborn and stillborn infants were included, as well as fetuses from elective terminations because of anomalies identified in prenatal testing. We present the findings in 14 infants, all liveborn, who had symbrachydactyly of one or both hands (n = 12) or feet (n = 2). We suggest restricting the term symbrachydactyly to this single phenotype to improve counseling and to focus future research on identifying the cause(s).

A novel homozygous variant in the GLI1 underlies postaxial polydactyly in a large consanguineous family with intra familial variable phenotypes.

Polydactyly is a human inherited disorder caused by to anomalies in the genes involved in autopod development. The disorder segregates in both autosomal recessive and autosomal dominant form. Up till now, eleven genes causing non-syndromic polydactyly, have been identified. This includes ZNF141, GLI3, ZRS in LMBR1, MIPOL1, PITX1, IQCE, GLI1, FMA92A1, KIAA0825, STKLD1, and DACH1. In the present study, we have investigated a large consanguineous family of Pakistani origin segregating polydactyly in autosomal recessive pattern. Clinical examination of affected individuals revealed a non-syndromic form of the disorder. Genetic study based on homozygosity mapping and Sanger sequencing using DNA of the normal and affected individuals found a novel homozygous missense sequence variant [NM_005269.3: c.1133C > T, p.(Ser378Leu)] in the GLI1 located on human chromosome 12q13.3. In silico analysis of the identified variant showed a significant change in the secondary structure of the mutant protein that affects its function. Findings of the present study expand the mutation spectrum of the GLI1. In addition, the study will help in prevention of the disorder through carrier testing and bringing awareness among families affected with polydactyly.

Prenatal Detection of Novel Compound Heterozygous Splice Site Variants of the KIAA0825 Gene in a Fetus with Postaxial Polydactyly Type A.

Postaxial polydactyly (PAP) is a common abnormality characterized by extra digits on hands and/or feet. To date, sequence variants in seven genes have been identified in non-syndromic PAP. In the present study, a fetus manifesting non-syndromic postaxial polydactyly type A (PAPA) was found by fetal ultrasonography. To better evaluate fetal prognosis, SNP array analysis and trio whole-exome sequencing (trio-WES) were performed to identify the underlying etiology. Although SNP array analysis revealed no abnormality, trio-WES identified compound heterozygous splice site variants in KIAA0825, c.-1-2A>T and c.2247-2A>G in intron 2 and intron 12, respectively. These two splice site variants were absent in control databases and were predicted to influence splicing by in silico analysis. To confirm the potential pathogenicity of the variants, in vitro splicing assays using minigene and RNA from peripheral leukocytes of the heterozygous parents were conducted. Minigene and RT-PCR assays demonstrated that the c.-1-2A>T variant led to the loss of the initiation codon, and the c.2247-2A>G variant mainly resulted in exon 13 skipping. Prenatal WES and subsequent functional studies are important approaches for defining the genetic etiology of fetuses with PAPA and are also essential for accurate genetic counseling and decision making. Taken together, this study expands the spectrum of KIAA0825 variations in PAPA patients and increases the knowledge of the molecular consequences of KIAA0825 splice site variants.

On-Top Plasty in Post-Axial Polydactyly: A Case Report and Recommendation to Modify the Classifications.

Post-axial polydactyly (PAP) is almost always treated by ablation of the sixth ray since the ulnar duplicate is universally inadequate and the radial one is normal. We report a patient with bilateral PAP with skeletal abnormalities in both radial and ulnar duplicates. This unusual presentation cannot be classified according to previous classifications of PAP and precludes simple ablation as the treatment of choice. Both hands of this patient were treated by on-top plasty with excellent functional and cosmetic results. A modification of the previous classifications is recommended at the end of this article. Level of Evidence: Level V (Therapeutic).

A case report on fibular aplasia, tibial campomelia, oligosyndactyly syndrome variant in a male infant.

Fibular aplasia, tibial campomelia, and oligosyndactyly (FATCO syndrome) is a rare, genetic, congenital limb malformation characterised by unilateral or bilateral fibular aplasia, tibial campomelia, and lower limb oligosyndactyly involving the lateral rays. A newborn male born at term via a Caesarean Section presented with malformations consisting of tibial campomelia, unilateral fibular hypoplasia, and oligosyndactyly, a "FATCO variant" case. On radiographic examination, an anterolateral shortened and bowed right lower limb at the distal third of the tibia, a rudimentary right fibula and absence of three rays on right foot were revealed. "FATCO syndrome" although rare may be linked to involvement of different body systems with morbidity and mortality. Proper parent counseling is a key aspect of this syndrome. Timely diagnosis and management with a multidisciplinary approach is essential to avoid lifelong disability, which can be a hurdle in a developing country.

A novel variant of GLI3, p.Asp1514Thrfs*5, is identified in a Chinese family affected by polydactyly.

BACKGROUND: Polydactyly is a common congenital malformation characterized by the presence of supernumerary fingers or toes. In this case study, we sought to identify the causative pathogenic factor in a family from a northern region of China affected by non-syndromic postaxial polydactyly (PAP). METHODS: After recruiting a three-generation family with PAP, whole-exome sequencing was performed to identify the causative variant. In silico analysis and Sanger sequencing were used to validate the variant. RESULTS: We identified a novel heterozygous frameshift variant (NM_000168.6:c.4540delG, p.Asp1514Thrfs*5) in the transcriptional activator (TA1) domain of the GLI3 gene. CONCLUSION: The novel frameshift variant identified in this study further confirms the relationship between non-syndromic PAP and GLI3 and extends the previously established mutational and phenotypic spectra of GLI3.

Whole-exome sequencing identified novel variants in CPLANE1 that causes oral-facial-digital syndrome â ¥ by inducing primary cilia abnormality.

Oral-facial-digital syndrome (OFDS) is a multisystemic ciliopathic disorder with an autosomal recessive mode of inheritance. OFDS usually manifests with typical craniofacial anomalies and variable occurrence of polydactyly. Germline variants in CPLANE1 cause OFDS VI. In this study, we investigated a 26-year-old Chinese female patient who was 23+1  weeks pregnant. She had a history of adverse pregnancy outcomes with multiple foetal malformations. We performed ultrasonography and identified the foetus as having a posterior fossa Blake cyst and postaxial polydactyly. The patient decided to terminate her pregnancy, and further genetic molecular analysis was performed. We identified the aborted foetus as having postaxial polydactyly. Whole-exome sequencing identified a missense variant (c.3599C>T, p.A1200V) in exon 20 and a c.834+1G>T variant in exon 7 of CPLANE1 (NM_023073.3) in the foetus. Sanger sequencing confirmed that these variants came from the parents of the foetus. In this study, we investigated a family with OFDS VI through genetic testing and bioinformatics analysis, which provided powerful help for prenatal diagnosis. Then, we demonstrated that the cell migration rate and the number of cilia were decreased after interference with CPLANE1 expression in NIH/3T3 cells. After CPLANE1 knockdown, the Hh signalling pathway was inhibited, and the Hh pathway activator SAG reversed the inhibitory effect. This is the first report of a family with OFDS VI in the Chinese population.

Bardet-Biedl syndrome: a case series.

BACKGROUND: Bardet-Biedl syndrome is a rare multisystem autosomal recessive disorder that falls under the spectrum of ciliopathy disorders. It is characterized by rod-cone dystrophy, renal malformations, polydactyly, learning difficulties, central obesity, and hypogonadism. Many minor features that are related with Bardet-Biedl syndrome might aid in diagnosis and are crucial in clinical management. Bardet-Biedl syndrome is diagnosed on the basis of clinical signs and symptoms, which can be confirmed by genetic testing. Here we present four cases of Bardet-Biedl syndrome. To our knowledge, these are the first cases of Bardet-Biedl syndrome reported from Sudan. CASE PRESENTATION: Here, we report four Sudanese patients who presented with a variety of clinical manifestations of Bardet-Biedl syndrome (two males, 50 and 16 years old; two females, 38 and 18 years old). The first two patients presented with features of chronic kidney disease. The third patient had recently been diagnosed with type 1 diabetes and diabetic ketoacidosis. The fourth patient showed signs of retinal dystrophy early on. Case 1: a 38-year-old female presented with vomiting and irritability; the patient was diagnosed with Bardet-Biedl syndrome as she fulfilled six items of the primary features (obesity, retinitis pigmentosa, post-axial polydactyly, renal abnormalities, learning disabilities, and genitourinary malformations), as well as one secondary feature (cardiovascular involvement, that is, left ventricular hypertrophy). Case 2: a 50-year-old male presented with fatigability; the patient was diagnosed with Bardet-Biedl syndrome as he fulfilled four items of the primary features (obesity, retinitis pigmentosa, post-axial polydactyly, and renal abnormalities) in addition to two secondary features (diabetes mellitus and cardiovascular involvement, that is, left ventricular hypertrophy). Case 3: an 18-year-old female presented with polyuria, polydipsia, weight loss, and epigastric pain for 2 days; the patient was diagnosed with Bardet-Biedl syndrome because he had four major features (retinal dystrophy, post-axial polydactyly, obesity, and learning disabilities) in addition to three secondary features (developmental delay, diabetes mellitus, and strabismus). Case 4: a 16-year-old male presented with a blurring of vision; the patient was diagnosed with Bardet-Biedl syndrome as he exhibited four major features (retinal dystrophy, post-axial polydactyly, obesity, and learning disabilities) plus two secondary features (developmental delay and cataract). CONCLUSION: The scarcity of Bardet-Biedl syndrome necessitates a high index of suspicion to diagnose this syndrome. Increased awareness among physicians is required for the early diagnosis and treatment of Bardet-Biedl syndrome and to avoid complications and mortality.

Phenotypic overlap between cardioacrofacial dysplasia-2 and oral-facial-digital syndrome.

Oral-facial digital (OFD) syndrome is characterized by abnormalities of the face (hypertelorism and low set-ears), oral cavity (multiple frenula, lingual hamartoma, or lobulated tongue) and extremities (postaxial polydactyly). At least 19 genes have been implicated in the development of OFD syndrome. Herein, we report the case a 13-year-old patient with atrioventricular septal defect, moderate intellectual disability, epilepsy, and features of OFD, including multiple oral frenula, and postaxial polydactyly of the hands and feet. The patient had a de novo heterozygous variant in PRKACB: chr1(GRCh37):g.84700915T > C, c.1124T > C (NM_182948.4), p.(Phe375Ser). To date, four patients with pathogenic monoallelic variants in PRKACB have been reported, and the condition associated with these variants is referred to as Cardioacrofacial dysplasia-2 (CAFD2, MIM619143). Previously reported features of this condition include congenital heart disease (e.g., atrioventricular septal defect) and postaxial polydactyly, and two of the patients had multiple oral frenula. We suggest that a significant phenotypic overlap exists between CAFD2 and OFD syndrome, in that these patients especially share the features of postaxial polydactyly and multiple oral frenula. The phenotypic similarity between patients with CAFD2 and classic OFD syndrome with an OFD1 variant might be explained by the recent in vitro experimental finding that a protein kinase A subunit encoded by PRKACB directly phosphorylates the OFD1 protein. From the standpoint of genetic counseling, OFD syndrome type1, the prototypic form of OFD, exhibits an X-linked dominant inheritance pattern, whereas other forms of OFD syndrome exhibit an autosomal recessive inheritance pattern. Recognition of CAFD2 as a differential diagnosis or forme fruste of OFD syndrome suggests that an autosomal dominant pattern of inheritance should also be considered during genetic counseling.

Examination of Postoperative Outcomes Using Morphological and X-Ray Classifications and Selection of the Toe to Be Excised in Postaxial Polydactyly of the Foot.

The treatment of postaxial polydactyly requires excision of the medial fifth or lateral sixth toe, and separation of the adjacent fourth/fifth toes if the adjacent toes exhibit skin syndactyly. Morphological changes in the retained toes and reoperation are common problems after such surgery. This study examined the effects of preoperative classifications and selecting the medial fifth or lateral sixth toe for excision on the postoperative outcomes of surgery for postaxial polydactyly. From April 2006 to March 2019, surgery for postaxial polydactyly was performed on 55 feet in 49 patients. The patients' mean age at surgery was 28.8 months. Postoperative esthetic and bone alignment scores, the reoperation rate, and postoperative dysfunction were examined. The postoperative esthetic and bone alignment evaluations were performed by examining postoperative photograph and X-ray images using original scoring systems. The surgical procedure was chosen by the surgeon-in-charge during a preoperative conference after considering the toe growth and bone alignment. In the postoperative esthetic evaluation, excising the lateral sixth toe produced significantly better outcomes than excising the medial fifth toe. The morphological classification also indicated that excising the lateral sixth toe produced better outcomes, as it resulted in the bifurcated toes being clearly independent. Interestingly, the postoperative X-ray-based bone alignment score was not correlated with the esthetic score. The reoperation rate tended to be high after medial fifth toe excision. There were no postoperative functional complications. Lateral sixth toe excision for postaxial polydactyly of the foot produces good postoperative esthetic outcomes.

Assessment of the severity of curly toe.

BACKGROUND: Curly/underlapping toe involves flexion, adduction, and varus deformity of the interphalangeal joints. There are no previous reports showing the relationship between physical examination and X-ray findings among patients with curly toe deformity. METHODS: We investigated the clinical findings of 116 consecutive patients associated with 239 underlapping toes. We compared the age and affected toes between patients whose deformities were pointed out at a pediatric medical examination (group 1) and those referred for medical treatment (group 2). The degree of curly toe deformity was graded by a physical examination and X-ray. RESULTS: The average age at presentation was 2.7 years. The affected toes were significantly different between groups 1 and 2 (p < .001). The morbidity of each toe differed significantly in group 2 (p < .005) but not in group 1. The correlation between the appearance grading and classification by X-ray was very strong using Spearman's rank correlation coefficient. The severity of curly toe was divided into mild in 104 toes, moderate in 105 toes, and severe in 17 toes. The methods of conservative treatment were observation only in 15 cases, manipulations in 30 cases, taping in 67 cases, and a brace in 9 cases. Surgery was performed in 8% of cases. CONCLUSION: Curly toe deformity of the third or fourth toes tend to be referred for medical treatment because of the abnormality. Our grading system using a physical examination and classification by X-ray was useful for assessing the severity of curly toe.