Associated anomalies in individuals with polydactyly

Skeletal ciliopathy: pathogenesis and related signaling pathways

Cilia are tiny organelles with conserved structures and components in eukaryotic cells. Ciliopathy is a set of diseases resulting from cilium dysfunction classified into first-order and second-order ciliopathy. With the advancement of clinical diagnosis and radiography, numerous skeletal phenotypes, including polydactyly, short limbs, short ribs, scoliosis, a narrow thorax, and numerous anomalies in bone and cartilage, have been discovered in ciliopathies. Mutation in genes encoding cilia core components or other cilia-related molecules have been found in skeletal ciliopathies. Meanwhile, various signaling pathways associated with cilia and skeleton development have been deemed to be significant for the occurrence and progression of diseases. Herein, we review the structure and key components of the cilium and summarize several skeletal ciliopathies with their presumable pathology. We also emphasize the signaling pathways involved in skeletal ciliopathies, which may assist in developing potential therapies for these diseases.

Paternal age and risk for selected birth defects in a large South American sample

BACKGROUND

The relationship between maternal age (MA) and birth defects (BD) has been extensively studied while much less research, mostly with discordant results, has focused on the risk of paternal age (PA) for BD. Furthermore, no consensus has been reached on the best way to control the association of PA with MA.

OBJECTIVES

The aim of the study was to evaluate the risk of PA increase, at 1-year intervals, for selected BD, especially controlling for the confounding effect of MA.

METHODS

The sample comprised of 27,944 liveborns presenting 1 of 18 selected isolated BD. Conditional logistic regressions were applied to evaluate the risk of advanced PA and its yearly increase, adjusting by MA and other variables.

RESULTS

Of the 18 analyzed BD, only the risk for preaxial polydactyly (PreP) showed a significant association with increasing PA, while advanced MA was of low risk. For esophageal and anal atresia, associations with both PA and MA increases were observed.

CONCLUSIONS

Results support the hypothesis of advanced PA as a risk factor for PreP and helps clarify the so far unexplained nonrandom association between this defect and Down syndrome.

Structural Evaluation and Conformational Dynamics of ZNF141T474I Mutation Provoking Postaxial Polydactyly Type A

Postaxial Polydactyly (PAP) is a congenital disorder of limb abnormalities characterized by posterior extra digits. Mutations in the N-terminal region of the Zinc finger protein 141 (ZNF141) gene were recently linked with PAP type A. Zinc finger proteins exhibit similarity at their N-terminal regions due to C2-H2 type Zinc finger domains, but their functional preferences vary significantly by the binding patterns of DNA. Methods: This study delineates the pathogenic association, miss-fold aggregation, and conformational paradigm of a missense variant (c.1420C > T; p.T474I) in ZNF141 gene segregating PAP through a molecular dynamics simulations approach. Results: In ZNF141 protein, helices play a crucial role by attaching three specific target DNA base pairs. In ZNF141T474I protein, H1, H3, and H6 helices attain more flexibility by acquiring loop conformation. The outward disposition of the proximal portion of H9-helix in mutant protein occurs due to the loss of prior beta-hairpins at the C terminal region of the C2-H2 domain. The loss of hydrogen bonds and exposure of hydrophobic residues to solvent and helices turning to loops cause dysfunction of ZNF141 protein. These significant changes in the stability and conformation of the mutant protein were validated using essential dynamics and cross-correlation maps, which revealed that upon point mutation, the overall motion of the proteins and the correlation between them were completely different, resulting in Postaxial polydactyly type A. Conclusions: This study provides molecular insights into the structural association of ZNF141 protein with PAP type A. Identification of active site residues and legends offers new therapeutic targets for ZNF141 protein. Further, it reiterates the functional importance of the last residue of a protein.

Application of quantitative fluorescent polymerase chain reaction analysis for the rapid confirmation of trisomy 13 of maternal origin in a pregnancy with fetal holoprosencephaly, cyclopia, polydactyly, omphalocele and cell culture failure

OBJECTIVE

We present the application of quantitative fluorescent polymerase chain reaction (QF-PCR) for the rapid confirmation of trisomy 13 of maternal origin in a pregnancy with fetal holoprosencephaly (HPE), cyclopia, polydactyly, omphalocele and cell culture failure.

CASE REPORT

A 21-year-old, gravida 2, para 0, woman was referred for termination of the pregnancy at 17 weeks of gestation because of the abnormal ultrasound finding of alobar HPE. The pregnancy was subsequently terminated, and a 118-g malformed male fetus was delivered with cyclopia, bilateral postaxial polydactyly of the hands and ruptured omphalocele. Postmortem cell culture of the placental tissue and umbilical cord was not successful. The parental karyotypes were normal. QF-PCR analysis using the polymorphic DNA markers of D13S1810, D13S790 and D13S251 on the DNA extracted from placenta, umbilical cord and parental bloods showed trisomy 13 of maternal origin.

CONCLUSION

Perinatal diagnosis of concomitant HPE, polydactyly and omphalocele should raise a suspicion of fetal trisomy 13. QF-PCR analysis is useful for rapid confirmation of trisomy 13 and the parental origin especially under the circumstance of cell culture failure, and the information acquired is very useful for genetic counseling of the parents.

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.

Complex Hand Polydactyly: A Case Report and Literature Review

Polydactyly is a common congenital malformation in which extra digits are present in at least one extremity. It has various presentations, and it can be an isolated anomaly or part of other diseases. Most isolated polydactyly cases are sporadic and unilateral, but there is an increased incidence in some populations. Polydactyly is multifactorial and can occur in different forms. Its main line of treatment is surgery to improve cosmesis and functioning. In this report, we present a rare case of bilateral complex hand polydactyly in a one-year-seven-months old girl of African descent. She is otherwise healthy with no family history of malformations. The pattern is not consistent with any syndromic disease. She subsequently underwent surgical resection of the extra digits.

Rapid diagnosis of trisomy 13 of maternal origin by quantitative fluorescent polymerase chain reaction analysis in a pregnancy with fetal holoprosencephaly, premaxillary agenesis, postaxial polydactyly of left hand and overriding aorta

OBJECTIVE

We present rapid diagnosis of trisomy 13 of maternal origin by quantitative fluorescent polymerase chain reaction (QF-PCR) in a pregnancy with multiple fetal abnormalities.

CASE REPORT

A 35-year-old, primigravid woman was referred for amniocentesis at 24 weeks of gestation because of multiple congenital anomalies in the fetus. Prenatal ultrasound at 23 weeks of gestation revealed holoprosencephaly, premaxillary agenesis, postaxial polydactyly of the left hand and overriding aorta. Amniocentesis was performed subsequently, and QF-PCR analysis using the polymorphic DNA markers of D13S789 (13q22.3), D13S790 (13q31.1) and D13S767 (13q31.3) on the DNA extracted from uncultured amniocytes and parental bloods showed trisomy 13 of maternal origin. Conventional cytogenetic analysis on the cultured amniocytes confirmed trisomy 13. The pregnancy was subsequently terminated, and a malformed fetus was delivered with multiple anomalies consistent with the prenatal diagnosis.

CONCLUSION

QF-PCR analysis is useful for rapid confirmation of trisomy 13 and the parental origin when prenatal ultrasound findings are suspicious of fetal trisomy 13.

Extreme bilateral polydactyly in a wild-caught western grey kangaroo

Polydactyly is a congenital malformation resulting from an autosomal dominant mutation manifesting as supernumerary digits of the hands or feet. It is most commonly reported in humans and domestic mammals, though there have also been isolated examples across a range of wild vertebrate species. Here we report a case of extremely unusual bilateral preaxial polydactyly on the pectoral limbs of a male western grey kangaroo (Macropus fuliginosus) from the South West region of Western Australia, in which two supernumerary digits were present on each manus. A supernumerary digit I on each manus was rudimentary in morphology without extrinsic muscular connections. However, supernumerary digit II present on each manus had fully developed extrinsic and intrinsic muscular connections, suggesting that these digits possessed normal function in flexion and extension. An alternative hypothesis is that the two supernumerary digits are both representatives of the most radial digit I, though this would then require the true digit I to have taken on the appearance of digit II by acquiring an additional phalanx and modified muscular attachments. The carpal bones exhibited a number of subtle differences in morphology when compared to normal pentadactyl individuals. The presence of a distal, rather than proximal, epiphysis on the first metacarpal was unexpected but further investigation suggested that this characteristic is perhaps more variable (in this species at least) than has been previously recognized. This case provides an unusual example to be considered within the broader context of limb development.

Co-occurring defect analysis: A platform for analyzing birth defect co-occurrence in registries

BACKGROUND

Few studies have systematically evaluated birth defect co-occurrence patterns, perhaps, in part, due to the lack of software designed to implement large-scale, complex analytic methods.

METHODS

We created an R-based platform, "co-occurring defect analysis" (CODA), designed to implement analyses of birth defect co-occurrence patterns in birth defect registries. CODA uses an established algorithm for calculating the observed-to-expected ratio of a given birth defect combination, accounting for the known tendency of birth defects to co-occur nonspecifically. To demonstrate CODA's feasibility, we evaluated the computational time needed to assess 2- to 5-way combinations of major birth defects in the Texas Birth Defects Registry (TBDR) (1999-2014). We report on two examples of pairwise patterns, defects co-occurring with trisomy 21 or with non-syndromic spina bifida, to demonstrate proof-of-concept.

RESULTS

We evaluated combinations of 175 major birth defects among 206,784 infants in the TBDR. CODA performed efficiently in the data set, analyzing 1.5 million 5-way combinations in 18 hr. As anticipated, we identified large observed-to-expected ratios for the birth defects that co-occur with trisomy 21 or spina bifida.

CONCLUSIONS

CODA is available for application to birth defect data sets and can be used to better understand co-occurrence patterns. Co-occurrence patterns elucidated by using CODA may be helpful for identifying new birth defect associations and may provide etiological insights regarding potentially shared pathogenic mechanisms. CODA may also have wider applications, such as assessing patterns of additional types of co-occurrence patterns in other large data sets (e.g., medical records).

Prenatal diagnosis of congenital mirror foot: case report and review

Polydactyly refers to a group of congenital anomalies characterized by the presence of more than five fingers or toes per extremity. Mirror foot is an extreme and rare form of foot polydactyly characterized by the presence of extra tarsal bones and digits and is most often an isolated finding recognized at birth. Here, we report the first case of mirror foot diagnosed prenatally at the time of routine second trimester ultrasound. This early diagnosis allowed for thorough counseling that provided the family adequate time to process the diagnosis and prepare for neonatal management.

FAM92A Underlies Nonsyndromic Postaxial Polydactyly in Humans and an Abnormal Limb and Digit Skeletal Phenotype in Mice

Polydactyly is a common congenital anomaly of the hand and foot. Postaxial polydactyly (PAP) is characterized by one or more posterior or postaxial digits. In a Pakistani family with autosomal recessive nonsyndromic postaxial polydactyly type A (PAPA), we performed genomewide genotyping, linkage analysis, and exome and Sanger sequencing. Exome sequencing revealed a homozygous nonsense variant (c.478C>T, p.[Arg160*]) in the FAM92A gene within the mapped region on 8q21.13-q24.12 that segregated with the PAPA phenotype. We found that FAM92A is expressed in the developing mouse limb and E11.5 limb bud including the progress zone and the apical ectodermal ridge, where it strongly localizes at the cilia level, suggesting an important role in limb patterning. The identified variant leads to a loss of the FAM92A/Chibby1 complex that is crucial for ciliogenesis and impairs the recruitment and the colocalization of FAM92A with Chibby1 at the base of the cilia. In addition, we show that Fam92a^-/- homozygous mice also exhibit an abnormal digit morphology, including metatarsal osteomas and polysyndactyly, in addition to distinct abnormalities on the deltoid tuberosity of their humeri. In conclusion, we present a new nonsyndromic PAPA ciliopathy due to a loss-of-function variant in FAM92A. © 2018 American Society for Bone and Mineral Research.

A loss-of-function homozygous mutation in DDX59 implicates a conserved DEAD-box RNA helicase in nervous system development and function

We report on a homozygous frameshift deletion in DDX59 (c.185del: p.Phe62fs*13) in a family presenting with orofaciodigital syndrome phenotype associated with a broad neurological involvement characterized by microcephaly, intellectual disability, epilepsy, and white matter signal abnormalities associated with cortical and subcortical ischemic events. DDX59 encodes a DEAD‐box RNA helicase and its role in brain function and neurological diseases is unclear. We showed a reduction of mutant cDNA and perturbation of SHH signaling from patient‐derived cell lines; furthermore, analysis of human brain gene expression provides evidence that DDX59 is enriched in oligodendrocytes and might act within pathways of leukoencephalopathies‐associated genes. We also characterized the neuronal phenotype of the Drosophila model using mutant mahe, the homolog of human DDX59, and showed that mahe loss‐of‐function mutant embryos exhibit impaired development of peripheral and central nervous system. Taken together, our results support a conserved role of this DEAD‐box RNA helicase in neurological function.

Pallister-Hall Syndrome

Polydactyly is a relatively common abnormality in infants. However, it can be a marker of a wide variety of neurological and systemic abnormality. Hence, it is important for pediatrician and physician to have insight into the various association of this apparently innocuous anomaly. In this write-up, we report an extremely rare syndrome associated with polydactyly that is Pallister–Hall syndrome. A 10-month-old male child born by lower segment cesarean section presented with global delay associated with microcephaly, frontal bossing, hypertelorism, flat nose, short philtrum, incomplete cleft in the upper lip and hard palate, polydactyly, and syndactyly. The child presented with repeated vomiting and crying episodes. The patient was investigated which revealed a hypothalamic hamartomas. Pallister–Hall syndrome is a very rare autosomal dominant genetic disorder due to mutation in GLI3 gene in the short arm of chromosome 7 with variable penetrance and expressivity.

Paleodysmorphology and paleoteratology: Diagnosing and interpreting congenital conditions of the skeleton in anthropological contexts

Most congenital conditions have low prevalence, but collectively they occur in a few percent of all live births. Congenital conditions are rarely encountered in anthropological studies, not least because many of them have no obvious effect on the skeleton. Here, we discuss two groups of congenital conditions that specifically affect the skeleton, either qualitatively or quantitatively. Skeletal dysplasias (osteochondrodysplasias) interfere with the histological formation, growth and maturation of skeletal tissues leading to diminished postural length, but the building plan of the body is unaffected. Well- known skeletal dysplasias represented in the archeological record include osteogenesis imperfecta and achondroplasia. Dysostoses, in contrast, interfere with the building plan of the body, leading to e.g. missing or extraskeletal elements, but the histology of the skeletal tissues is unaffected. Dysostoses can concern the extremities (e.g., oligodactyly and polydactyly), the vertebral column (e.g., homeotic and meristic anomalies), or the craniofacial region. Conditions pertaining to the cranial sutures, i.e., craniosynostoses, can be either skeletal dysplasias or dysostoses. Congenital conditions that are not harmful to the individual are known as anatomical variations, several of which have a high and population-specific prevalence that could potentially make them useful for determining ethnic origins. In individual cases, specific congenital conditions could be determinative in establishing identity, provided that ante-mortem registration of those conditions was ensured. Clin. Anat. 29:878-891, 2016. © 2016 The Authors Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Descriptive analysis of high birth prevalence rate geographical clusters of congenital anomalies in South America

BACKGROUND

The birth prevalence rate (BPR) of congenital anomalies (CAs) is heterogeneous and exhibits geographical and sociocultural variations throughout the world. In South America (SA), high birth prevalence regions of congenital anomalies have been observed. The aim of this study was to identify, describe, and characterize geographical clusters of congenital anomalies in SA.

METHODS

This observational descriptive study is based on clinical epidemiological data registered by the Latin-American Collaborative Study of Congenital Malformations network. Between 1995 and 2012, a total of 25,082 malformed newborns were ascertained from 2,557,424 births at 129 hospitals in SA. The spatial scan statistic was used to determine geographical regions with high BPR of CAs. The BPR was obtained with a Poisson regression model. Odds ratios were estimated for several risk factors inside the geographical clusters.

RESULTS

We confirmed the existence of high BPR regions of CAs in SA. Indicators of low socioeconomic conditions, such as a low maternal education, extreme age childbearing, infectious diseases, and medicine use during pregnancy were detected as risk factors inside these regions. Native and African ancestries with high frequency of consanguineous marriages could explain partially these high BPR clusters.

CONCLUSION

The recognition of clusters could be a starting point in the identification of susceptibility genes associated with the occurrence of CA in high BPR regions.

NOSOLOGY OF HAND DISEASES IN CHILDREN AND ADOLESCENTS OPERATED IN PROVISIONAL FACILITIES IN A MODEL HOSPITAL - PERNAMBUCO STATE, BRAZIL

To report the frequencies of congenital hand diseases in patients who underwent surgery on a collective mobilization basis at SOS Hand, Recife, Pernambuco, between 2005 and 2009. Methods: Information was collected from 833 children and adolescents who were examined in eight missions. Results: Among the patients, 306 (36.7%) underwent surgery: 240 (78.4%) because of congenital malformation and 66 (21.6%) because of acquired lesions. The most frequent congenital malformations were: syndactyly, 72 cases (30.0%); polydactyly, 30 cases (12.5%); bifid thumb, 19 cases (7.9%); complex hand malformation, 14 cases (5.8%); cleft hand, 13 cases (5.4%); trigger finger, 12 cases (5.0%); camptodactyly, 11 cases (4.6%); and brachysyndactyly, 9 cases (3.7%). The most frequently acquired injuries were: obstetric traumatic lesions, 26 cases (39.4%); hand trauma sequelae, 18 cases (27.3%); cerebral paralysis sequelae, 7 cases (10.6%); electric shock sequelae, 5 cases (7.6%); and burn sequelae, 4 cases (6.1%). Conclusion: The nosology of hand diseases is similar to that of large series of elective surgery, especially regarding congenital deformities. The frequency of acquired hand lesions seems to be higher than the frequency in international series. The collective mobilization system for hand surgery is important for decreasing the need for this activity in public institutions, and it has been shown to be very efficient. The success of the project may provide support for the Brazilian National Health System to enroll hand surgeons in the on-call system, in emergency units.

Rare presentation of foot postaxial polydactyly

Polydactyly is a prevalent birth anomaly observed in the foot, and a number of classification systems have been suggested for this condition. Postaxial (fifth or little toe) polydactyly is the most common type. We encountered an exceedingly rare presentation of foot postaxial polydactyly that, to our inspection, had neither been previously classified nor described in published studies. In the present report, we have described an otherwise healthy 2-year-old female who had presented to our clinic with an isolated, extra little toe on her left foot. Foot radiographs revealed the presence of all 5 metatarsals; however, the fifth metatarsal was blocked and did not give rise to the fifth toe. Instead, the fifth (medial normal) and sixth (lateral extra) toes had originated from a single, separate accessory bud from the fourth metatarsal, and the main fourth metatarsal had given rise to the normal fourth toe. The lateral sixth toe was excised, and a periosteal sleeve of the excised extra toe was used for reconstruction of the lateral collateral ligament. We propose that this heretofore unmentioned presentation of postaxial polydactyly be added to the existing systems of classification of pedal polydactyly. A review of the published data pertaining to pedal polydactyly has also been presented.

Birth prevalence for congenital limb defects in the northern Netherlands: a 30-year population-based study

Background

Reported birth prevalences of congenital limb defects (CLD) vary between countries: from 13/10,000 in Finland for the period 1964–1977 to 30.4/10,000 births in Scotland from 1964–1968. Epidemiological studies permit the timely detection of trends in CLD and of associations with other birth defects. The aim of this study is to describe the birth prevalence of CLD in the northern Netherlands.

Methods

In a population-based, epidemiological study we investigated the birth prevalences of CLD for 1981–2010. Data were collected by the European Surveillance of Congenital Anomalies in the northern Netherlands (EUROCAT-NNL). We excluded malpositions, club foot, and dislocation/dysplasia of hips or knees. Trends were analysed for the 19-year period 1992–2010 using χ² tests, as well as CLD association with anomalies affecting other organs.

Results

The birth prevalence of CLD was 21.1/10,000 births for 1981–2010. There was an overall decrease in non-syndromic limb defects (P = 0.023) caused by a decrease in the prevalence of non-syndromic syndactyly (P < 0.01) in 1992–2010. Of 1,048 children with CLD, 55% were males, 57% had isolated defects, 13% had multiple congenital anomalies (MCA), and 30% had a recognised syndrome. The upper:lower limb ratio was 2:1, and the left:right side ratio was 1.2:1. Cardiovascular and urinary tract anomalies were common in combination with CLD (37% and 25% of cases with MCA). Digestive-tract anomalies were significantly associated with CLD (P = 0.016).

Conclusions

The birth prevalence of CLD in the northern Netherlands was 21.1/10,000 births. The birth prevalence of non-syndromic syndactyly dropped from 5.2/10,000 to 1.1/10,000 in 1992–2010.

Polydactyly: phenotypes, genetics and classification

Polydactyly is one of the most common hereditary limb malformations featuring additional digits in hands and/or feet. It constituted the highest proportion among the congenital limb defects in various epidemiological surveys. Polydactyly, primarily presenting as an additional pre-axial or post-axial digit of autopod, is a highly heterogeneous condition and depicts broad inter- and intra-familial clinical variability. There is a plethora of polydactyly classification methods reported in the medical literature which approach the heterogeneity in polydactyly in various ways. In this communication, well-characterized, non-syndromic polydactylies in humans are reviewed. The cardinal features, phenotypic variability and molecular advances of each type have been presented. Polydactyly at cellular and developmental levels is mainly a failure in the control of digit number. Interestingly, GLI3 and SHH (ZRS/SHH enhancer), two antagonistic factors known to modulate digit number and identity during development, have also been implicated in polydactyly. Mutations in GLI3 and ZRS/SHH cause overlapping polydactyly phenotypes highlighting shared molecular cascades in the etiology of additional digits, and thus suggesting the lumping of at least six distinct polydactyly entities. However, owing to the extreme phenotypic and clinical heterogeneity witnessed in polydactyly a substantial genetic heterogeneity is expected across different populations and ethnic groups.

Familial crossed polysyndactyly in four generations of an Indian family

BACKGROUND

Polydactyly is the most common malformation of the limbs. "Crossed" polydactyly of hands and feet, i.e., preaxial in one and postaxial in the other, is extremely rare. It has not been included in the standard classification of hand and feet anomalies.

METHODS

We report an Indian family with 7 affected members across 4 generations who had "crossed polysyndactyly". All but one affected member had involvement of all four limbs. There were no other congenital anomalies in any of the family members.

RESULTS

Familial crossed polysyndactyly appeared to follow an autosomal dominant transmission. This is probably the first case of familial crossed polysyndactyly without any associated anomalies.

CONCLUSION

Familial crossed polysyndactyly is a rare malformation and all family members should be screened for other congenital malformations.

Implication of long-distance regulation of the HOXA cluster in a patient with postaxial polydactyly

Apparently balanced chromosomal inversions may lead to disruption of developmentally important genes at the breakpoints of the inversion, causing congenital malformations. Characterization of such inversions may therefore lead to new insights in human development. Here, we report on a de novo inversion of chromosome 7 (p15.2q36.3) in a patient with postaxial polysyndactyly. The breakpoints do not disrupt likely candidate genes for the limb phenotype observed in the patient. However, on the p-arm the breakpoint separates the HOXA cluster from a gene desert containing several conserved noncoding elements, suggesting that a disruption of a cis-regulatory circuit of the HOXA cluster could be the underlying cause of the phenotype in this patient.

Why did the savant syndrome not spread in the population? A psychiatric example of a developmental constraint

A developmental constraint is a mechanism that limits the possibility of a phenotype to evolve. There is growing evidence for the existence of developmental constraints in the biological literature. We hypothesize that a developmental constraint prevents the savant syndrome, despite its positive aspects, from spreading in the population. Here, the developmental constraint is the result of the high interactivity among body parts in an early stage in embryological development, namely early organogenesis or the phylotypic stage. The interactivity during this stage involves all components of the embryo, and as a result mutations that affect one part of the embryo also affect other parts. We hypothesize that a mutation, which gives rise to the development of the positive aspects of the savant syndrome (e.g., an impressive memory capacity), will virtually always have a deleterious effect on the development of other phenotypic traits (e.g., resulting in autism and/or impaired motor coordination). Thus, our hypothesis states that the savant syndrome cannot spread in the population because of this developmental constraint. The finding that children with savant syndrome often have autism and physical anomalies, which are known to be established during early organogenesis, supports our hypothesis.

Left hand polydactyly: a case report

Background

Polydactyly is a congenital anomaly with a wide range of manifestations that occurs in many forms, ranging from varying degrees of mere splitting to completely duplicated thumb. When duplication occurs alone, it is usually unilateral and sporadic.

Case presentation

In this case report we describe an otherwise healthy 19-year-old woman of Tibetan heritage with isolated left hand preaxial polydactyly. She experienced working related difficulties in her daily yak's milking. She subsequently underwent surgical correction, and the over number thumb was removed with associated meticulous skeletal and soft tissue reconstruction.

Conclusion

Polydactyly is the most common congenital digital anomaly of the hand and foot. It can occur in isolation or as part of a syndrome. Surgery is necessary to create a single, functioning thumb and is indicated to improve cosmesis. Skin, nail, bone, ligament, and musculoskeletal elements must be combined to reconstruct an optimal digit. In this case (Tibetan society is almost exclusively a sheep-breeding one) surgery was necessary to leave a single, functioning thumb for her work as yak milkmaid.

Molecular diagnostics of Meckel-Gruber syndrome highlights phenotypic differences between MKS1 and MKS3

Meckel-Gruber syndrome (MKS) is a recessively inherited, lethal disorder characterized by renal cystic dysplasia, occipital encephalocele, polydactyly and biliary dysgenesis. MKS is genetically heterogeneous with three loci mapped and two identified; MKS1 (17q23) and MKS3 (8q22.1). MKS1 is part of the Finnish disease heritage, while MKS3 has been described exclusively in consanguineous Asian families. Here we aimed to establish molecular diagnostics for MKS, determine the importance of MKS1 and MKS3 in non-consanguineous populations, and study genotype/phenotype correlations. The coding regions of MKS1 and MKS3 were screened for mutations by direct sequencing in 17 families clinically diagnosed with MKS in the US or The Netherlands. The clinical phenotype was compared to genic and allelic effects. Both mutations were identified in ten families; five MKS1 and five MKS3. All but two were compound heterozygotes, consistent with their non-consanguineous nature. The MKS1-Fin(major) mutation accounted for 7/10 MKS1 mutations; two novel changes were additionally detected. Seven novel mutations were found in MKS3, including three missense changes. We concluded that MKS1 and MKS3 account for the majority of MKS in non-consanguineous populations of European origin. Polydactyly is usually found in MKS1 but rare in MKS3. Cases with no, or milder, CNS phenotypes were only found in MKS3; hypomorphic missense mutations may be associated with less severe CNS outcomes. This study is consistent with further genetic heterogeneity of MKS, but underlines the value of molecular diagnostics of the known genes to aid family planning decisions.

Microcephaly, distinctive facies, single atrium, postaxial polydactyly, skeletal defects and mental retardation: a new familial faciocardiomelic syndrome?

Three siblings with postaxial polydactyly type A, congenital heart defect (single atrium), mental retardation, microcephaly, a distinctive facial appearance, skeletal anomalies and neonatal macrosomy were studied. Comparison with other cardiomelic syndromes previously described in the literature lead us to conclude that this is a new faciocardiomelic syndrome probably inherited as an autosomal recessive trait.

[Association of neonatal polydactyly and maternal glucose tolerance impairment in the Congolese environment]

OBJECTIVES

To determine the expression of neonatal polydactyly in Kinshasa along with its association with maternal glucose tolerance impairment.

MATERIALS AND METHODS

The study group is made of 151 non diabetic women whose neonates had polydactyly (isolated in 115 cases and associated with other malformations in 36 cases). The control group was made up of mothers with normal infants, 151 who had no history of congenital malformations and 39 others with a history of polydactyly in the family. The mothers had an Oral Glucose Tolerance Test (OGTT) within 24 hours after delivery.

RESULTS

Bilateral type B postaxial Hand polydactyly was the most frequent form (42.3% of cases). Polydactyly was associated with other congenital malformations in 23.1%. In the study group, carbohydrate intolerance was observed in 24.3% when polydactyly was isolated, and 44.4% when it was associated with other congenital malformations. In the control group the frequency of carbohydrate intolerance was 1.9%. The positive predictive value of carbohydrate intolerance by Bilateral type B Hand polydactyly was 80.6%, while the negative predictive value was 70.1%.

CONCLUSION

These results suggest a carbohydrate intolerance during the peri-conceptional period. An OGTT can be recommended for mothers whose newborns have Bilateral type B Hand polydactyly.

Smith-Lemli-Opitz syndrome in trisomy 13: how does the mix work?

BACKGROUND

Trisomy 13 and Smith-Lemli-Opitz syndrome (SLOS) are both well-recognized multiple congenital anomaly/mental retardation syndromes.

CASE

In this report we describe a male newborn with trisomy 13 who also has features of SLOS, such as 2/3 toe syndactyly and a shawl-like scrotum. Biochemical analysis was consistent with SLOS, and limited molecular analysis revealed 1 mutation in the DHCR7 gene.

CONCLUSIONS

The challenges in establishing the diagnosis of SLOS in this patient are presented and the unique coexistence of the 2 major malformation syndromes is discussed. Given the overlapping phenotype of the 2 syndromes, our report should encourage further research on cholesterol biosynthesis in patients with trisomy 13.

Prenatal sonographic diagnosis of focal musculoskeletal anomalies

Focal musculoskeletal anomalies vary, and can manifest as part of a syndrome or be accompanied by numerous other conditions such as genetic disorders, karyotype abnormalities, central nervous system anomalies and other skeletal anomalies. Isolated focal musculoskeletal anomaly does, however, also occur; its early prenatal diagnosis is important in deciding prenatal care, and also helps in counseling parents about the postnatal effects of numerous possible associated anomalies. We have encountered 50 cases involving focal musculoskeletal anomalies, including focal limb dysplasia [radial ray abnormality (n=3), mesomelic dysplasia (n=1)]; anomalies of the hand [polydactyly (n=8), syndactyly (n=3), ectrodactyly (n=1), clinodactyly (n=6), clenched hand (n=5)]; anomalies of the foot [clubfoot (n=10), rockerbottom foot (n=5), sandal gap deformity (n=1), curly toe (n=2)]; amniotic band syndrome (n=3); and anomalies of the focal spine [block vertebra (n=1), hemivertebra (n=1)]. Among these 50 cases, five [polydactyly (n=1), syndactyly (n=2) and curly toe (n=2)] were confirmed by postnatal physical evaluation, two (focal spine anomalies) were diagnosed after postnatal radiologic examination, and the remaining 43 were proven at autopsy. For each condition, we describe the prenatal sonographic findings, and include a brief review.

Isolated postaxial polydactyly type B with mosaicism of a submicroscopic unbalanced translocation leading to an extended phenotype in offspring

Postaxial polydactyly (PAP) is characterized by the presence of one or more extra ulnar or fibular digits or parts of it. PAP type B presents frequently as a skin tag on the hand(s). It is usually an isolated malformation, but in 6.6% it is associated with other congenital abnormalities, mostly well recognizable syndromes. We present a male with PAP-B only and his daughter with an extended phenotype including mental retardation and minor dysmorphisms. Both share a cytogenetically balanced t(4;7)(p15.2;q35), present in mosaicism in the father. We found microdeletions associated with the breakpoints. The chromosomal regions described here have not been previously associated with the PAP-B phenotype. We present the first case of an individual with isolated PAP-B and a submicroscopic chromosome abnormality.

A new locus for postaxial polydactyly type A/B on chromosome 7q21-q34

Postaxial polydactyly (PAP) is the occurrence of one or more extra ulnar or fibular digits or parts of it. In PAP-A, the extra digit is fully developed and articulates with the fifth or an additional metacarpal/metatarsal, while it is rudimentary in PAP-B. Isolated PAP usually segregates as an autosomal dominant trait, with variable expression. Three loci are known for PAP in humans. PAPA1 (including PAP-A/B in one patient) on 7p13 caused by mutations in the GLI3 gene, PAPA2 on 13q21-q32 in a Turkish kindred with PAP-A only, and a third one (PAPA3) in a Chinese family with PAP-A/B on 19p13.1-13.2. We identified a fourth locus in a large Dutch six-generation family with 31 individuals including 11 affecteds. Their phenotype varied from either PAP-A, or PAP-B to PAP-A/B with or without the co-occurence of partial cutaneous syndactyly. We performed a whole-genome search and found linkage between PAP and markers on chromosome 7q. The highest LOD score was 3.34 obtained at D7S1799 and D7S500 with multipoint analysis.

Molecular pathology and genetics of congenital hepatorenal fibrocystic syndromes

The hepatorenal fibrocystic (HRFC) syndromes are a heterogeneous group of severe monogenic conditions that may be detected before birth. Commonly, HRFC syndromes present in the neonatal and paediatric age, with consistent developmental abnormalities mostly involving the liver and kidney. The changes include the proliferation and dilatation of epithelial ducts in these tissues with abnormal deposition of extracellular matrix. In this review, we examine the clinical features and differential diagnoses of this group of syndromes, including autosomal recessive polycystic kidney disease (ARPKD), juvenile nephronophthisis (NPHP), Meckel-Gruber syndrome (MKS), Bardet-Biedl syndrome (BBS), and Jeune asphyxiating thoracic dystrophy (JATD). Extrahepatic manifestations include mostly bone and central nervous system abnormalities, dysmorphic features, and developmental delay. Previously, it has been suggested that ARPKD, JATD, and Ellis-van Creveld syndrome (EvC) may arise from defects in differentiation in a common developmental pathway. We review recent molecular advances in the recessive HRFC syndromes and discuss this hypothesis.

The chick oligozeugodactyly (ozd) mutant lacks sonic hedgehog function in the limb

We have analyzed a new limb mutant in the chicken that we name oligozeugodactyly (ozd). The limbs of this mutant have a longitudinal postaxial defect, lacking the posterior element in the zeugopod (ulna/fibula) and all digits except digit 1 in the leg. Classical recombination experiments show that the limb mesoderm is the defective tissue layer in ozd limb buds. Molecular analysis revealed that the ozd limbs develop in the absence of Shh expression, while all other organs express Shh and develop normally. Neither Ptc1 nor Gli1 are detectable in mutant limb buds. However, Bmp2 and dHAND are expressed in the posterior wing and leg bud mesoderm, although at lower levels than in normal embryos. Activation of Hoxd11-13 occurs normally in ozd limbs but progressively declines with time. Phase III of expression is more affected than phase II, and expression is more severely affected in the more 5' genes. Interestingly, re-expression of Hoxd13 occurs at late stages in the distal mesoderm of ozd leg buds, correlating with formation of digit 1. Fgf8 and Fgf4 expression are initiated normally in the mutant AER but their expression is progressively downregulated in the anterior AER. Recombinant Shh protein or ZPA grafts restore normal pattern to ozd limbs; however, retinoic acid fails to induce Shh in ozd limb mesoderm. We conclude that Shh function is required for limb development distal to the elbow/knee joints, similar to the Shh(-/-) mouse. Accordingly we classify the limb skeletal elements as Shh dependent or independent, with the ulna/fibula and digits other than digit 1 in the leg being Shh dependent. Finally we propose that the ozd mutation is most likely a defect in a regulatory element that controls limb-specific expression of Shh.

Isolated polydactyly: prenatal diagnosis and perinatal outcome

Our objective was to determine the clinical significance of isolated polydactyly identified on prenatal sonogram. All patients with sonographically detected isolated polydactyly scanned over an 11-year period were identified from our database. All patients underwent detailed surveys, and follow-up was obtained by review of the medical records and telephone conversations with parents and referring physicians. Thirteen patients with isolated polydactyly were identified. Follow-up was available in 12 patients. Indications for referral included advanced maternal age (2), second-opinion polydactyly (4), family history of polydactyly (1), uncertain dates (5), and growth (1). The gestational ages at the times of sonographic diagnosis ranged from 17.5 to 34 weeks with all but one case being identified before 23 weeks. Prenatal identification included polydactyly of the upper limb (8), lower limb (4), and both upper and lower limbs (1). Postaxial polydactyly was seen in 12 patients and preaxial in one. Polydactyly was confirmed in all 12 cases in which follow-up was available. Karyotypes were normal in all five fetuses in which amniocentesis was performed. Ten of 12 fetuses were born alive, one died in utero at 34 weeks as a complication of severe pre-eclampsia and one died at term as a result of a cord accident. No surviving neonate had any other identifiable malformation or suspected karyotypic abnormality. In conclusion isolated polydactyly identified by prenatal sonography is associated with good perinatal outcome.