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Clinical Genetics Jan 2023Polydactyly or polydactylism, also known as a hyperdactyly, is a congenital limb defect with various morphologic phenotypes. Apart from physical and functional... (Review)
Review
Polydactyly or polydactylism, also known as a hyperdactyly, is a congenital limb defect with various morphologic phenotypes. Apart from physical and functional impairments, the presence of polydactyly is an indication of an underlying syndrome in the newborn. Usually, it follows as an autosomal dominant/recessive inheritance pattern with defects in the limb development's anteroposterior patterning. Although mutations in several genes have been associated with polydactyly; however, the exact underlying cause, pathways, and disease mechanisms are still unexplored, thus making it of multi-factorial origin. Polydactyly is divided into three subtypes; radial, ulnar, and central polydactyly. So far, 11 loci (PAPA1-PAPA11) and seven human genes have been reported to cause non-syndromic postaxial polydactyly in humans, including the ZNF141, GLI3, IQCE, GLI1, FAM92A1, KIAA0825, and DACH1. In this review, we discuss emerging evidences of clinical and molecular characterization of polydactyly types in term of the involvement of newly associated genes and loci for non-syndromic postaxial polydactyly, and how these might impact our understanding of the genetic mechanisms and molecular etiology involved in the cause of polydactyly.
Topics: Infant, Newborn; Humans; Polydactyly
PubMed: 36071556
DOI: 10.1111/cge.14224 -
Frontiers in Oncology 2024Somatic mutations in have been identified across various tumors, playing pivotal roles in tumorigenesis, tumor progression, and unfavorable prognoses. Despite its... (Review)
Review
Somatic mutations in have been identified across various tumors, playing pivotal roles in tumorigenesis, tumor progression, and unfavorable prognoses. Despite its established notoriety as an oncogenic driver, there is a growing interest in exploring the involvement of MYCN in human development. While variants have traditionally been associated with Feingold syndrome type 1, recent discoveries highlight gain-of-function variants, specifically p.(Thr58Met) and p.(Pro60Leu), as the cause for megalencephaly-polydactyly syndrome. The elucidation of cellular and murine analytical data from both loss-of-function (Feingold syndrome model) and gain-of-function models (megalencephaly-polydactyly syndrome model) is significantly contributing to a comprehensive understanding of the physiological role of MYCN in human development and pathogenesis. This review discusses the MYCN's functional implications for human development by reviewing the clinical characteristics of these distinct syndromes, Feingold syndrome, and megalencephaly-polydactyly syndrome, providing valuable insights into the understanding of pathophysiological backgrounds of other syndromes associated with the MYCN pathway and the overall comprehension of MYCN's role in human development.
PubMed: 38884091
DOI: 10.3389/fonc.2024.1417607 -
Current Opinion in Pediatrics Feb 2023Polydactyly presents with variable extent of duplication and may involve preaxial/radial (hand)/medial (foot), postaxial/ulnar (hand)/lateral (foot) or central... (Review)
Review
PURPOSE OF REVIEW
Polydactyly presents with variable extent of duplication and may involve preaxial/radial (hand)/medial (foot), postaxial/ulnar (hand)/lateral (foot) or central duplication. This review will summarize recent advancements in the surgical management of this common entity.
RECENT FINDINGS
Modifications to classification systems aim to help guide surgical management of polydactyly. Attempts have been made at quantifying preoperative angulation of the duplicated digits to minimize the chance of residual or recurrent deformity after surgical reconstruction. As a result, consideration should be given to the need for soft tissue correction vs. osteotomy to optimize the clinical outcome. On-top plasty is an option that may be beneficial in 'unequal' preaxial polydactyly, where neither duplicate is preferred on its own.
SUMMARY
Polydactyly is one of the most common congenital anomalies in the hands and feet. Determination of surgical intervention often begins with classification systems that exist, which primarily separate these into preaxial, postaxial, and central. Referral for surgical consideration is indicated, given the management is often surgical.
Topics: Humans; Polydactyly; Thumb; Plastic Surgery Procedures; Osteotomy
PubMed: 36412268
DOI: 10.1097/MOP.0000000000001204 -
Developmental Dynamics : An Official... Apr 2022Primary cilia are dynamic compartments that regulate multiple aspects of cellular signaling. The production, maintenance, and function of cilia involve more than 1000... (Review)
Review
Primary cilia are dynamic compartments that regulate multiple aspects of cellular signaling. The production, maintenance, and function of cilia involve more than 1000 genes in mammals, and their mutations disrupt the ciliary signaling which manifests in a plethora of pathological conditions-the ciliopathies. Skeletal ciliopathies are genetic disorders affecting the development and homeostasis of the skeleton, and encompass a broad spectrum of pathologies ranging from isolated polydactyly to lethal syndromic dysplasias. The recent advances in forward genetics allowed for the identification of novel regulators of skeletogenesis, and revealed a growing list of ciliary proteins that are critical for signaling pathways implicated in bone physiology. Among these, a group of protein kinases involved in cilia assembly, maintenance, signaling, and disassembly has emerged. In this review, we summarize the functions of cilia kinases in skeletal development and disease, and discuss the available and upcoming treatment options.
Topics: Animals; Cilia; Ciliopathies; Homeostasis; Mammals; Polydactyly; Proteins
PubMed: 34582081
DOI: 10.1002/dvdy.426 -
Nature Feb 2024Enhancers control the location and timing of gene expression and contain the majority of variants associated with disease. The ZRS is arguably the most well-studied...
Enhancers control the location and timing of gene expression and contain the majority of variants associated with disease. The ZRS is arguably the most well-studied vertebrate enhancer and mediates the expression of Shh in the developing limb. Thirty-one human single-nucleotide variants (SNVs) within the ZRS are associated with polydactyly. However, how this enhancer encodes tissue-specific activity, and the mechanisms by which SNVs alter the number of digits, are poorly understood. Here we show that the ETS sites within the ZRS are low affinity, and identify a functional ETS site, ETS-A, with extremely low affinity. Two human SNVs and a synthetic variant optimize the binding affinity of ETS-A subtly from 15% to around 25% relative to the strongest ETS binding sequence, and cause polydactyly with the same penetrance and severity. A greater increase in affinity results in phenotypes that are more penetrant and more severe. Affinity-optimizing SNVs in other ETS sites in the ZRS, as well as in ETS, interferon regulatory factor (IRF), HOX and activator protein 1 (AP-1) sites within a wide variety of enhancers, cause gain-of-function gene expression. The prevalence of binding sites with suboptimal affinity in enhancers creates a vulnerability in genomes whereby SNVs that optimize affinity, even slightly, can be pathogenic. Searching for affinity-optimizing SNVs in genomes could provide a mechanistic approach to identify causal variants that underlie enhanceropathies.
Topics: Humans; Enhancer Elements, Genetic; Extremities; Gain of Function Mutation; Homeodomain Proteins; Interferon Regulatory Factors; Organ Specificity; Penetrance; Phenotype; Polydactyly; Polymorphism, Single Nucleotide; Protein Binding; Proto-Oncogene Proteins c-ets; Transcription Factor AP-1
PubMed: 38233525
DOI: 10.1038/s41586-023-06922-8 -
Journal of Clinical Orthopaedics and... 2020Anomalies of the thumb development are not uncommon and may be associated with a number of syndromes also. These anomalies range from total absence to duplication.... (Review)
Review
Anomalies of the thumb development are not uncommon and may be associated with a number of syndromes also. These anomalies range from total absence to duplication. Reconstructive surgery for the creation of an opposable thumb is the most rewarding aspect of Hand Surgery and also the most challenging. Classification systems have been modified for better description. A number of procedures have been introduced to improve the functionality of the hand in anomalies and age old concepts are undergoing a metamorphosis to further this. A brief description of the common conditions and their treatment are discussed here and highlighted by selected clinical cases.
PubMed: 32684694
DOI: 10.1016/j.jcot.2020.06.018 -
Cells Jul 2021Although ubiquitously present, the relevance of cilia for vertebrate development and health has long been underrated. However, the aberration or dysfunction of ciliary... (Review)
Review
Although ubiquitously present, the relevance of cilia for vertebrate development and health has long been underrated. However, the aberration or dysfunction of ciliary structures or components results in a large heterogeneous group of disorders in mammals, termed ciliopathies. The majority of human ciliopathy cases are caused by malfunction of the ciliary dynein motor activity, powering retrograde intraflagellar transport (enabled by the cytoplasmic dynein-2 complex) or axonemal movement (axonemal dynein complexes). Despite a partially shared evolutionary developmental path and shared ciliary localization, the cytoplasmic dynein-2 and axonemal dynein functions are markedly different: while cytoplasmic dynein-2 complex dysfunction results in an ultra-rare syndromal skeleto-renal phenotype with a high lethality, axonemal dynein dysfunction is associated with a motile cilia dysfunction disorder, primary ciliary dyskinesia (PCD) or Kartagener syndrome, causing recurrent airway infection, degenerative lung disease, laterality defects, and infertility. In this review, we provide an overview of ciliary dynein complex compositions, their functions, clinical disease hallmarks of ciliary dynein disorders, presumed underlying pathomechanisms, and novel developments in the field.
Topics: Animals; Axonemal Dyneins; Cilia; Ciliopathies; Cytoplasmic Dyneins; Humans; Kartagener Syndrome; Polymorphism, Genetic; Short Rib-Polydactyly Syndrome
PubMed: 34440654
DOI: 10.3390/cells10081885 -
Revista Paulista de Pediatria : Orgao... 2023To evaluate radiological (gestational and perinatal) and neonatal signs of patients with Patau syndrome and semilobar holoprosencephaly, as well as to report the...
OBJECTIVE
To evaluate radiological (gestational and perinatal) and neonatal signs of patients with Patau syndrome and semilobar holoprosencephaly, as well as to report the association of both pathologies.
CASE DESCRIPTION
This case report is about a female infant, born at term with trisomy of the chromosome 13 and semilobar holoprosencephaly, with thalamic fusion and a single cerebral ventricle, in addition to several other changes that worsened the patient's prognosis.
COMMENTS
Chromosome 13 trisomy is a genetic alteration that leads to the symptoms that determines Patau syndrome. In this syndrome, cardiovascular, urogenital, central nervous system, facial structure and intellectual impairment are common, in addition to problems in limb formation, such as decreased humerus and femur length, polydactyly, hypotelorism and low ear implantation. It is estimated, however, that holoprosencephaly is present in only 24 to 45% of the patients with trisomy 13.
Topics: Infant, Newborn; Pregnancy; Infant; Humans; Female; Holoprosencephaly; Trisomy 13 Syndrome; Trisomy; Polydactyly; Mutation; Chromosomes, Human, Pair 13
PubMed: 36921175
DOI: 10.1590/1984-0462/2023/41/2022027 -
European Journal of Human Genetics :... Nov 2023Polydactyly is the most common limb malformation that occurs in 1.6-10.6 per one thousand live births, with incidence varying with ancestry. The underlying gene has been...
Polydactyly is the most common limb malformation that occurs in 1.6-10.6 per one thousand live births, with incidence varying with ancestry. The underlying gene has been identified for many of the ~100 syndromes that include polydactyly. While for the more common form, nonsydromic polydactyly, eleven candidate genes have been reported. We investigated the underlying genetic cause of autosomal recessive nonsyndromic postaxial polydactyly in four consanguineous Pakistani families. Some family members with postaxial polydactyly also present with syndactyly, camptodactyly, or clinodactyly. Analysis of the exome sequence data revealed two novel homozygous frameshift deletions in EFCAB7: [c.830delG;p.(Gly277Valfs*5)]; in three families and [c.1350_1351delGA;p.(Asn451Phefs*2)] in one family. Sanger sequencing confirmed that these variants segregated with postaxial polydactyly, i.e., family members with postaxial polydactyly were found to be homozygous while unaffected members were heterozygous or wild type. EFCAB7 displays expressions in the skeletal muscle and on the cellular level in cilia. IQCE-EFCAB7 and EVC-EVC2 are part of the heterotetramer EvC complex, which is a positive regulator of the Hedgehog (Hh) pathway, that plays a key role in limb formation. Depletion of either EFCAB7 or IQCE inhibits induction of Gli1, a direct Hh target gene. Variants in IQCE and GLI1 have been shown to cause nonsyndromic postaxial polydactyly, while variants in EVC and EVC2 underlie Ellis van Creveld and Weyers syndromes, which include postaxial polydactyly as a phenotype. This is the first report of the involvement of EFCAB7 in human disease etiology.
Topics: Humans; Hedgehog Proteins; Zinc Finger Protein GLI1; Polydactyly; Fingers; Limb Deformities, Congenital
PubMed: 37684519
DOI: 10.1038/s41431-023-01450-5 -
Journal of Medical Case Reports Apr 2022Bardet-Biedl syndrome is a rare multisystem autosomal recessive disorder that falls under the spectrum of ciliopathy disorders. It is characterized by rod-cone...
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.
Topics: Adolescent; Adult; Bardet-Biedl Syndrome; Female; Fingers; Humans; Hypertrophy, Left Ventricular; Kidney; Learning Disabilities; Male; Middle Aged; Obesity; Polydactyly; Retinitis Pigmentosa; Toes; Urogenital Abnormalities
PubMed: 35484558
DOI: 10.1186/s13256-022-03396-6