A novel GLI3 frameshift mutation in a Chinese pedigree with polydactyly: A case report

Background

GLI3 gene mutations can result in various forms of polysyndactyly, such as Greig cephalopolysyndactyly syndrome (GCPS, MIM: #175700), Pallister-Hall syndrome (PHS, MIM: #146510), and isolated polydactyly (IPD, MIM: #174200, #174700). Reports on IPD-associated GLI3 mutations are rare. In this study, a novel GLI3 mutation was identified in a Chinese family with IPD.

Results

We report a family with six members affected by IPD. The family members demonstrated several special phenotypes, including sex differences, abnormal finger joint development, and different polydactyly types. We identified a novel frameshift variant in the GLI3 gene (NM_000168.6: c.1820_1821del, NP_000159.3: p.Tyr607Cysfs*9) by whole-exome sequencing. Further analysis suggested that this mutation was the cause of polydactyly in this family.

Conclusions

The discovery of this novel frameshift variant in our study further solidifies the relationship between IPD and GLI3 and expands the previously established spectrum of GLI3 mutations and associated phenotypes.

Queering the genome: ethical challenges of epigenome editing in same-sex reproduction

In this article, I explore the ethical dimensions of same-sex reproduction achieved through epigenome editing-an innovative and transformative technique. For the first time, I analyse the potential normativity of this disruptive approach for reproductive purposes, focusing on its implications for lesbian couples seeking genetically related offspring. Epigenome editing offers a compelling solution to the complex ethical challenges posed by traditional gene editing, as it sidesteps genome modifications and potential long-term genetic consequences. The focus of this article is to systematically analyse the bioethical issues related to the use of epigenome editing for same-sex reproduction. I critically assess the ethical acceptability of epigenome editing with reproductive purposes from multiple angles, considering harm perspectives, the comparison of ethical issues related to gene and epigenome editing, and feminist theories. This analysis reveals that epigenome editing emerges as an ethically acceptable means for lesbian couples to have genetically related children. Moreover, the experiments of a reproductive use of epigenome editing discussed in this article transcend bioethics, shedding light on the broader societal implications of same-sex reproduction. It challenges established notions of biological reproduction and prompts a reevaluation of how we define the human embryo, while poses some issues in the context of gender self-identification and family structures. In a world that increasingly values inclusivity and diversity, this article aims to reveal a progressive pathway for reproductive medicine and bioethics, as well as underscores the need for further philosophical research in this emerging and fertile domain.

Preaxial polydactyly of the foot in an adult patient diagnosed by X-ray after a trauma

Polydactyly, or hyperdactyly, is a frequent malformation, with a reported incidence between 0.37 and 1.2 per 1000 live births. Most cases encountered in medical practice are sporadic cases, usually presenting one-sided manifestations. More frequently, polydactyly can be detected prenatally through an ultrasound examination, if not, it is usually diagnosed at birth, during the first physical examination. Although the clinical diagnosis is relatively easy in patients with manifest cases, it can sometimes be present with mild or partial forms that are not clinically evident on physical examination, resulting in later diagnosis and treatment. We reported a particular case of polydactyly of the foot not clinically manifest, diagnosed in a 39-year-old Caucasian Male patient with a history of recurrent localized pain in the big toe often associated with subungual bleeding, since he was a child who came to our emergency room following a car accident. Polydactyly is a frequently reported congenital malformation which may present in many different varieties of deformities. In this case, the X-ray, which was required after a car accident, leads to the incidental diagnosis of polydactyly in an adult patient. As described, because of the functional limitations related to this malformation, as well as to limit recurrent pain, and subungual anomalies, the patient underwent to a surgical correction to improve its quality of life.

Atavistic and vestigial anatomical structures in the head, neck, and spine: an overview

Organisms may retain nonfunctional anatomical features as a consequence of evolutionary natural selection. Resultant atavistic and vestigial anatomical structures have long been a source of perplexity. Atavism is when an ancestral trait reappears after loss through an evolutionary change in previous generations, whereas vestigial structures are remnants that are largely or entirely functionless relative to their original roles. While physicians are cognizant of their existence, atavistic and vestigial structures are rarely emphasized in anatomical curricula and can, therefore, be puzzling when discovered incidentally. In addition, the literature is replete with examples of the terms atavistic and vestigial being used interchangeably without careful distinction between them. We provide an overview of important atavistic and vestigial structures in the head, neck, and spine that can serve as a reference for anatomists and clinical neuroscientists. We review the literature on atavistic and vestigial anatomical structures of the head, neck, and spine that may be encountered in clinical practice. We define atavistic and vestigial structures and employ these definitions consistently when classifying anatomical structures. Pertinent anatomical structures are numerous and include human tails, plica semilunaris, the vomeronasal organ, levator claviculae, and external ear muscles, to name a few. Atavistic and vestigial structures are found throughout the head, neck, and spine. Some, such as human tails and branchial cysts may be clinically symptomatic. Literature reports indicate that their prevalence varies across populations. Knowledge of atavistic and vestigial anatomical structures can inform diagnoses, prevent misrecognition of variation for pathology, and guide clinical interventions.

GLIS Family Zinc Finger 1 was First Linked With Preaxial Polydactyly I in Humans by Stepwise Genetic Analysis

Background: Preaxial polydactyly (PPD) is one of the most common developmental malformations, with a prevalence of 0.8–1.4% in Asians. PPD is divided into four types, PPD I–IV, and PPD I is the most frequent type. Only six loci (GLI1, GLI3, STKLD1, ZRS, pre-ZRS, and a deletion located 240 kb from SHH) have been identified in non-syndromic PPD cases. However, pathogenesis of most PPD patients has never been investigated. This study aimed to understand the genetic mechanisms involved in the etiology of PPD I in a family with multiple affected members.

Methods: We recruited a PPD I family (PPD001) and used stepwise genetic analysis to determine the genetic etiology. In addition, for functional validation of the identified GLIS1 variant, in vitro studies were conducted. GLIS1 variants were further screened in additional 155 PPD cases.

Results: We identified a GLIS1 variant (NM_147193: c.1061G > A, p.R354H) in the PPD001 family. In vitro studies showed that this variant decreased the nuclear translocation of GLIS1 and resulted in increased cell viability and migration. RNA sequencing revealed abnormal TBX4 and SFRP2 expression in 293T cells transfected with mutant GLIS1. Additionally, we identified a GLIS1 variant (c.664G > A, p.D222N) in another PPD case.

Conclusion: We identified two GLIS1 variants in PPD I patients and first linked GLIS1 with PPD I. Our findings contributed to future molecular and clinical diagnosis of PPD and deepened our knowledge of this disease.

Unusual congenital polydactyly in mini-pigs from the breeding group of the Institute of Cytology and Genetics (Novosibirsk, Russia)

The article describes a new phenomenon in the breeding group of mini-pigs at the Institute of Cytology and Genetics (ICG, Novosibirsk): polydactyly (extra digits), which is unusual because the additional digits are situated at the lateral surface of legs or at the lateral and medial ones. This anomaly was f irst found here in 2017 in adult animals intended for culling due to incorrect positioning of the legs caused by f lexor tendon laxity and resulting in weight-bearing on the palmar surface of the proximal phalanges (“bear’s paw”). Therefore, the polydactyly of mini-pigs has a pronounced negative selection effect. A visual survey of the livestock was conducted, and a description of the detected anomaly was compiled. The polydactyly in mini-pigs is a stand-alone trait and is not part of any syndromes. Individuals with polydactyly may have extra digits either on pectoral or on pectoral and pelvic limbs. On thoracic limbs, there may be either one lateral digit or a lateral digit and a medially located rudimentary hoof let. On pelvic limbs, only lateral extra digits can occur. Anatomical and morphological analyses showed that the lateral extra digit is an anatomically complete (“mature”) structure, whereas the medial rudimentary digit consists of only a hoof let without other structures characteristic of normal digits. Cytological examination revealed no specif ic karyotypic features, except for Robertsonian translocation Rb 16;17 previously reported for the mini-pigs of the same livestock. Cytological f indings indicated that the polydactyly and Robertsonian translocation are not linked genetically. Genealogical analysis and results of crosses are consistent with a working hypothesis of recessive inheritance of the trait. Overall, the study shows that this type of polydactyly is anatomically and morphologically unique and not typical of Sus scrofa. In this species, only polydactyly types with medial accessory toes have been described and are usually inherited as a dominant trait with incomplete penetrance. In our case, the results of test crosses indicate recessive inheritance of the trait with varying expression and incomplete penetrance, because of which poorly expressed phenotypes are not visually detectable.

Scientific patronage in the age of Darwin: The curious case of William Boyd Dawkins

This essay examines the curious relationship between Charles Darwin and the palaeontologist William Boyd Dawkins (1837-1929). Dawkins was a beneficiary of Darwin's patronage and styled himself as a Darwinian to Darwin and the public, yet viciously attacked Darwin and his theory in anonymous reviews. This has confused historians who have misunderstood the exact nature of Dawkins's attitude towards evolution and his relationship to Darwin. The present study explains both the reasons for Dawkins's contradictory statements and his relationship with Darwin. I introduce Batesian mimicry as a conceptual framework to make sense of Dawkins's actions, suggesting that Dawkins mimicked a Darwinian persona in order to secure advancement in the world of Victorian science. Dawkins's pro-Darwinian stance, therefore, was a façade, an act of mimicry. I argue that Dawkins exploited Darwin for his patronage - which took the form of advice, support from Darwin's well-placed friends, and monetary assistance - while safely expressing his dissent from Darwinian orthodoxy in the form of anonymous reviews. This is, therefore, a case study in how scientific authority and power could be gained and maintained in Victorian science by professing allegiance to Darwin and Darwinism.

An intrafamilial phenotypic variability in Ellis-Van Creveld syndrome due to a novel 27 bps deletion mutation

Ellis-van Creveld (EvC) syndrome is an autosomal recessive disease, characterized by ectodermal, skeletal, and cardiac anomalies. We report intrafamilial phenotypic variability in three new EvC syndrome cases. Affected males in this study showed only ectodermal abnormalities, whereas an affected female showed the classical presentation of EvC Syndrome, including bilateral postaxial polydactyly of hands and feet, and congenital heart defects. Whole exome sequencing was performed to identify the causative variant, followed by validation and segregation analysis using Sanger sequencing. A homozygous deletion variant (c.731_757del) was identified in exon 6 of the EVC gene (NM_153717.2). The identified variant is considered to be the most likely candidate variant for the EvC syndrome in the family based on previous reports validating the role of EVC variants in the EvC syndrome. The disease correctly segregated in the family members, as all affected members were homozygous, and obligate carriers were heterozygous. Our family is remarkable in highlighting the variable expressivity of the EvC phenotype within the same family, due to a homozygous deletion mutation in the EVC gene. The variable expressivity might be due to the hypomorphic nature of mutation, or the presence of additional variants in modifier genes or in the regulatory regions of the EVC/EVC2 genes.

Clinical Genetics of Polydactyly: An Updated Review

Polydactyly, also known as hyperdactyly or hexadactyly is the most common hereditary limb anomaly characterized by extra fingers or toes, with various associated morphologic phenotypes as part of a syndrome (syndromic polydactyly) or may occur as a separate event (non-syndromic polydactyly). Broadly, the non-syndromic polydactyly has been classified into three types, i.e.; preaxial polydactyly (radial), central polydactyly (axial), and postaxial polydactyly (ulnar). Mostly inherited as an autosomal dominant entity with variable penetrance and caused by defects that occur in the anterior-posterior patterning of limb development. In humans, to-date at least 10 loci and six genes causing non-syndromic polydactyly have been identified, including the ZNF141, GLI3, MIPOL1, IQCE, PITX1, and the GLI1. In the present review, clinical, genetic and molecular characterization of the polydactyly types has been presented including the recent genes and loci identified for non-syndromic polydactyly. This review provides an overview of the complex genetic mechanism underlie polydactyly and might help in genetic counseling and quick molecular diagnosis.

Prehistoric polydactylism: Biological evidence and rock art representation from the Atacama Desert in northern Chile

A review of the bioarchaeological collections from the site Morro de Arica in northern Chile allowed the identification of two cases of human polydactyly. Both cases are from the Chinchorro culture, hunters, fishers, and gatherers with a maritime orientation who inhabited the coast of the Atacama Desert (9000-3400 BP). Additionally, the analyses of 75 rock art sites in the area, from the Formative to Late Intermediate Periods (3000-550 BP), allowed the identification of hands and feet with six digits. Given the bioarchaeological record of polydactyly, it is highly probable that the rock art images were based on real individuals with polydactyly. However, the Sr chemical signal in a juvenile with polydactyly is the same as the Sr chemical signal in the rest of the individuals buried in the same site, proving that all the individuals were born and lived on the coast. We discuss the idea that, although these anomalies could have been the result of genetic mutations, endogamy and exposition to ecotoxic environments could also be at play within the Chinchorro groups.