Wieacker-Wolff syndrome with associated cleft palate in a female case

Case Report: A novel missense variant in ZC4H2, c.196C>T p.(Leu66Phe), is associated with a mild, ZC4H2-related X-linked syndromic intellectual disability (ZARD) phenotype

ZC4H2 is an X-linked gene that has emerged as critical for neural development, synaptic functioning, and gene regulation. We present an 11-month-old male who was evaluated for bilateral congenital vertical talus identified in the newborn period. Exome sequencing identified a hemizygous, missense variant in ZC4H2, NM_018684.4:c.196C>T p.(Leu66Phe), that affects the same amino acid residue as a previously reported, pathogenic ZC4H2 variant, c.197T>A p.(Leu66His). The variant was inherited from his mother, who had camptodactyly of the fifth fingers, and was also present in the maternal uncle who carried a diagnosis of cerebral palsy. The pathogenic missense variant in this family is located in the coiled-coil domain of the ZC4H2 protein. Although data remain scarce, missense variants in this domain may be associated with a milder, ZC4H2-associated rare disorder (ZARD) phenotype.

Genotype-Phenotype Correlations and Sex Differences in ZC4H2-Associated Rare Disorder

BACKGROUND

ZC4H2-associated rare disorder (ZARD) is caused by pathogenic variations in the ZC4H2 gene on the X chromosome. This gene codes for a zinc finger protein involved in neural development. ZARD is characterized by highly variable symptoms, potentially influenced by the sex of the individual.

METHODS

The ZC4H2-Associated Rare Disorder Natural History Study is a prospective natural history study conducted among individuals with ZARD that consists of standardized interviews, developmental assessments, and neurological examinations conducted every six months for two years. In this article, we present data from baseline visits with 40 participants, the largest ZARD cohort studied thus far, focusing on genotype-phenotype correlations and sex differences. Fisher exact, maximum likelihood χ2, and Mann-Whitney tests were utilized.

RESULTS

Males tended to have maternally inherited ZC4H2 pathogenic variations, whereas females tended to have de novo variations (P < 0.001). Female participants were more likely to have contractures at birth (P < 0.01), arthrogryposis multiplex congenita (P < 0.001), spasticity on examination (P < 0.1), and lower limb muscle atrophy (P < 0.05). Male participants were more likely to have seizures (P < 0.1), intermittent pain (P < 0.01), severe vision impairment (P < 0.05), dysphagia for solids (P < 0.01), and generalized muscle atrophy (P < 0.05).

CONCLUSIONS

Our study suggests there is significant overlap in severity and range of symptoms between males and females, although several symptoms are more common in one sex than the other. Further analysis is needed to better understand how pathogenic variation type affects phenotype.

Why Craniofacial Surgeons/Researchers Need to be Aware of Native American Myopathy?

Congenital myopathy type 13 (CMYO13), also known as Native American myopathy, is a rare muscle disease characterized by early-onset hypotonia, muscle weakness, delayed motor milestones, and susceptibility to malignant hyperthermia. The phenotypic spectrum of congenital myopathy type 13 is expanding, with milder forms reported in non-native American patients. The first description of the disease dates to 1987 when Bailey and Bloch described an infant belonging to a Native American tribe with cleft palate, micrognathia, arthrogryposis, and general-anesthesia-induced malignant hyperthermia reaction; the cause of the latter remains poorly defined in this rare disease. The pan-ethnic distribution, as well as its predisposition to malignant hyperthermia, makes the identification of CMYO13 essential to avoid life-threatening, anesthesia-related complications. In this article, we are going to review the clinical phenotype of this disease and the pathophysiology of this rare disease with a focus on two unique features of the disease, namely cleft palate and malignant hyperthermia. We also highlight the importance of recognizing this disease's expanding phenotypic spectrum-including its susceptibility to malignant hyperthermia-and providing appropriate care to affected individuals and families.

Optic nerve abnormalities in female-restricted Wieacker-Wolff syndrome by a novel variant in the ZC4H2 gene

BACKGROUND

Wieacker-Wolff syndrome is an ultra-rare disease with X-linked inheritance characterized by arthrogryposis, intellectual disability, microcephaly, and distal limb muscle atrophy. Ophthalmic abnormalities such as ptosis, strabismus, and oculomotor apraxia have been reported in half of the patients. Wieacker-Wolff syndrome female-restricted (WRWFFR) is an even rarer disease recently used for females with a more severe phenotype.

MATERIALS AND METHODS

Clinical geneticist and ophthalmic examination, neuroimaging, and exome sequencing.

RESULTS

A 4 years-old girl with developmental and language delay, microcephaly, camptodactyly, digital pads, and arthrogryposis was identified by the clinical geneticist. Ophthalmic examination revealed deep-set eyes, high hyperopic astigmatism in both eyes, and reduced retinal nerve fiber layer thickness measured by optical coherence tomography. Exome sequencing identified a novel, probably pathogenic variant in the ZC4H2 gene NM_018684.3:c.145A>T p. (Lys49*) in heterozygosis.

DISCUSSION

WRWFFR is an ultra-rare disease with X-linked inheritance by variants in the ZC4H2 gene. This case reports a girl with a novel nonsense variant in the ZC4H2 gene and a severe phenotype; previous reports have identified WRWFFR in females with large deletions and nonsense mutations which could explain the manifestations in the current case report. A complete ophthalmic examination should be considered in patients with WRWFFR to detect the possibly associated optic nerve involvement and other previously described manifestations such as ptosis and strabismus.

Expanding allelic and phenotypic spectrum of ZC4H2-related disorder: A novel hypomorphic variant and high prevalence of tethered cord

ZC4H2 (MIM# 300897) is a nuclear factor involved in various cellular processes including proliferation and differentiation of neural stem cells, ventral spinal patterning and osteogenic and myogenic processes. Pathogenic variants in ZC4H2 have been associated with Wieacker-Wolff syndrome (MIM# 314580), an X-linked neurodevelopmental disorder characterized by arthrogryposis, development delay, hypotonia, feeding difficulties, poor growth, skeletal abnormalities, and dysmorphic features. Zebrafish zc4h2 null mutants recapitulated the human phenotype, showed complete loss of vsx2 expression in brain, and exhibited abnormal swimming and balance problems. Here we report 7 new patients (four males and three females) with ZC4H2-related disorder from six unrelated families. Four of the 6 ZC4H2 variants are novel: three missense variants, designated as c.142T>A (p.Tyr48Asn), c.558G>A (p.Met186Ile) and c.602C>T (p.Pro201Leu), and a nonsense variant, c.618C>A (p.Cys206*). Two variants were previously reported : a nonsense variant c.199C>T (p.Arg67*) and a splice site variant (c.225+5G>A). Five patients were on the severe spectrum of clinical findings, two of whom had early death. The male patient harboring the p.Met186Ile variant and the female patient that carries the p.Pro201Leu variant have a relatively mild phenotype. Of note, 4/7 patients had a tethered cord that required a surgical repair. We also demonstrate and discuss previously under-recognized phenotypic features including sleep apnea, arrhythmia, hypoglycemia, and unexpected early death. To study the effect of the missense variants, we performed microinjection of human ZC4H2 wild-type or variant mRNAs into zc4h2 null mutant zebrafish embryos. The p.Met186Ile mRNA variant was able to partially rescue vsx2 expression while p.Tyr48Asn and p.Pro201Leu mRNA variants were not. However, swimming and balance problems could not be rescued by any of these variants. These results suggest that the p.Met186Ile is a hypomorphic allele. Our work expands the genotypes and phenotypes associated with ZC4H2-related disorder and demonstrates that the zebrafish system is a reliable method to determine the pathogenicity of ZC4H2 variants.

A novel ZC4H2 variant in a female with severe respiratory complications

INTRODUCTION

An X-linked ZC4H2 variant is associated with a variety of phenotypes that have abnormalities related to external malformation and neurodevelopment. There have been no reports on severe respiratory dysfunction resulting in surgical treatments not being possible due to the deformity resulting from in this disease. Here we report a female with arthrogryposis multiplex congenita with a severe respiratory complication.

CASE

A two-year-old girl had arthrogryposis multiplex congenita at delivery and subsequently had hypotonia and feeding difficulty. A novel ZC4H2 frameshift variant was identified by whole-exome sequencing in her genome. At eight months, she had recurrent aspiration pneumonia. A tracheostomy and gastrostomy were required; however, surgical intervention was not possible because of her short neck and complicated airway.

CONCLUSION

We compared this case with previous reports. The truncation group had more described phenotypes than the non-truncation group. The patient had the most severe respiratory dysfunction in truncating variant.

Loss of Protein Function Causing Severe Phenotypes of Female-Restricted Wieacker Wolff Syndrome due to a Novel Nonsense Mutation in the ZC4H2 Gene

Pathogenic variants of zinc finger C4H2-type containing (ZC4H2) on the X chromosome cause a group of genetic diseases termed ZC4H2-associated rare disorders (ZARD), including Wieacker-Wolff Syndrome (WRWF) and Female-restricted Wieacker-Wolff Syndrome (WRWFFR). In the current study, a de novo c.352C>T (p.Gln118*) mutation in ZC4H2 (NM_018684.4) was identified in a female neonate born with severe arthrogryposis multiplex congenita (AMC) and Pierre-Robin sequence (cleft palate and micrognathia). Plasmids containing the wild-type (WT), mutant-type (MT) ZC4H2, or GFP report gene (N) were transfected in 293T cell lines, respectively. RT-qPCR and western blot analysis showed that ZC4H2 protein could not be detected in the 293T cells transfected with MT ZC4H2. The RNA seq results revealed that the expression profile of the MT group was similar to that of the N group but differed significantly from the WT group, indicating that the c.352C>T mutation resulted in the loss of function of ZC4H2. Differentially expressed genes (DEGs) enrichment analysis showed that c.352C>T mutation inhibited the expression levels of a series of genes involved in the oxidative phosphorylation pathway. Subsequently, expression levels of ZC4H2 were knocked down in neural stem cells (NSCs) derived from induced pluripotent stem cells (iPSCs) by lentiviral-expressed small hairpin RNAs (shRNAs) against ZC4H2. The results also demonstrated that decreasing the expression of ZC4H2 significantly reduced the growth of NSCs by affecting the expression of genes related to the oxidative phosphorylation signaling pathway. Taken together, our results strongly suggest that ZC4H2 c.352C>T (p.Gln118*) mutation resulted in the loss of protein function and caused WRWFFR.

Variable Phenotypes of ZC4H2-Associated Rare Disease in Six Patients

PurposeWieacker-Wolff syndrome is a rare disease caused by X-linked zinc finger C4H2-type containing (ZC4H2) mutations. It is characterized by arthrogryposis multiplex congenita (AMC) and intellectual disability (ID), including impairment of central and peripheral synaptic plasticity. Currently, it is named “ZC4H2-associated rare disease” (ZARD) due to various clinical features other than AMC and ID. Here, we report six cases of ZARD, and describe their variable clinical phenotypes.MethodsWe analyzed the detailed clinical features and genotypes of six patients diagnosed by whole-exome sequencing or a chromosomal microarray.ResultsIn the four male patients, hemizygous mutations were found (c. 245A>C in two patients, c. 610C>A in one patient, and c.637C>T in one patient), and all variants were identified by Sanger sequencing. In the female patients, a 1.16-Mb deletion in Xq11.2, including ZC4H2, was identified by chromosomal microarray. All patients had heterogeneous phenotypes with variable severities. Motor delay was observed in all patients, four of whom could not walk independently. Other neurological features included ID, spasticity, and seizures. The craniofacial features included microcephaly, low-set ears, strabismus, ptosis, ocular motor apraxia, a U-shaped upper lip vermilion, short neck, and microretrognathia. The most common musculoskeletal symptoms were multiple arthrogryposis: metacarpophalangeal joint contracture, clubfoot, distal muscle weakness, Achilles tendon contracture, knee flexion contracture, camptodactyly, elbow flexion contracture, and hip subluxation.ConclusionThe ZARD phenotypes were prominent in male patients, and female patients with loss of function showed more severe symptoms. Further research is needed to clarify phenotypic variability in this rare disorder.

The many faces of the E3 ubiquitin ligase, RNF220, in neural development and beyond

Ubiquitin modification plays important roles in many cellular processes that are fundamental for vertebrate embryo development, such as cell division, differentiation, and migration. Aberrant function or deregulation of ubiquitination enzymes can cause developmental disorders, cancer progression, and neurodegenerative diseases in humans. RING finger protein 220 (RNF220) is an evolutionarily conserved RING-type ubiquitin E3 ligase. Recent studies have revealed the roles and mechanisms of RNF220 and its partner protein, zinc finger C4H2-type containing protein (ZC4H2), in embryonic development and human diseases. Using mouse and zebrafish models, it has been shown that RNF220 regulates sonic hedgehog (Shh) signaling via Gli and embryonic ectoderm development (EED), a polycomb repressive complex 2 (PRC2) component, during ventral neural patterning and cerebellum development. In addition, RNF220 also regulates the development and functions of central noradrenergic and motor neurons in mice. By stabilizing β-catenin and signal transducer and activator of transcription 1 (STAT1), RNF220 is also involved in Wnt and interferon (IFN)-STAT1 signaling and thus the regulation of tumorigenesis and immune response, respectively. In humans, both RNF220 and ZC4H2 mutations have been reported to be associated with diseases accompanied by complicated neural defects. In this review, we summarize the current knowledge of RNF220 with special emphasis on its roles and mechanisms of action in signal transduction, vertebrate neural development, and related human disorders.

Wieacker-Wolff syndrome, a distinctive phenotype of arthrogryposis multiplex congenita caused by a "de novo" ZC4H2 gene partial deletion

Unusual fetal arthrogryposis on ultrasound should draw attention to look for additional lower limb anomalies. Precise genetic counseling may be obtained from deletion on Xq11.2 as for ZC4H2 gene sequencing diagnostic for Wieacker-Wolff syndrome.

Neuromuscular and Neuroendocrinological Features Associated With ZC4H2-Related Arthrogryposis Multiplex Congenita in a Sicilian Family: A Case Report

Wieacker-Wolff syndrome (WWS) is an X-linked Arthrogryposis Multiplex Congenita (AMC) disorder associated with broad neurodevelopmental impairment. The genetic basis of WWS lies in hemizygous pathogenic variants in ZC4H2, encoding a C4H2 type zinc-finger nuclear factor abundantly expressed in the developing human brain. The main clinical features described in WWS families carrying ZC4H2 pathogenic variants encompass having a short stature, microcephaly, birth respiratory distress, arthrogryposis, hypotonia, distal muscle weakness, and broad neurodevelopmental delay. We hereby report a Sicilian family with a boy clinically diagnosed with WWS and genetically investigated with exome sequencing (ES), leading to the identification of a c.593G>A (p. R198Q) hemizygous pathogenic variant in the ZC4H2 gene. During the first year of life, the onset of central hypoadrenalism led to recurrent hypoglycemic events, which likely contributed to seizure susceptibility. Also, muscle biopsy studies confirmed a pathology of the muscle tissue and revealed peculiar abnormalities of the neuromuscular junction. In conclusion, we expand the phenotypic spectrum of the WWS-related neurodevelopmental disorders and discuss the role of ZC4H2 in the context of the potential neuroendocrinological and neuromuscular features associated with this condition.

Loss of ZC4H2 and RNF220 Inhibits Neural Stem Cell Proliferation and Promotes Neuronal Differentiation

The ubiquitin E3 ligase RNF220 and its co-factor ZC4H2 are required for multiple neural developmental processes through different targets, including spinal cord patterning and the development of the cerebellum and the locus coeruleus. Here, we explored the effects of loss of ZC4H2 and RNF220 on the proliferation and differentiation of neural stem cells (NSCs) derived from mouse embryonic cortex. We showed that loss of either ZC4H2 or RNF220 inhibits the proliferation and promotes the differentiation abilities of NSCs in vitro. RNA-Seq profiling revealed 132 and 433 differentially expressed genes in the ZC4H2^−/− and RNF220^−/− NSCs, compared to wild type (WT) NSCs, respectively. Specifically, Cend1, a key regulator of cell cycle exit and differentiation of neuronal precursors, was found to be upregulated in both ZC4H2^−/− and RNF220^−/− NSCs at the mRNA and protein levels. The targets of Cend1, such as CyclinD1, Notch1 and Hes1, were downregulated both in ZC4H2^−/− and RNF220^−/− NSCs, whereas p53 and p21 were elevated. ZC4H2^−/− and RNF220^−/− NSCs showed G0/G1 phase arrest compared to WT NSCs in cell cycle analysis. These results suggested that ZC4H2 and RNF220 are likely involved in the regulation of neural stem cell proliferation and differentiation through Cend1.

A novel de novo nonsense mutation in ZC4H2 causes Wieacker-Wolff Syndrome

Background

Wieacker‐Wolff syndrome (WWS) is a congenital X‐linked neuromuscular disorder, which was firstly reported in 1985. Zinc finger C4H2‐type containing (ZC4H2) gene has been found to be associated with the disease pathogenesis. However, the underlying mechanism remains elusive.

Methods

Whole‐exome sequencing was performed to identify the mutations. Expression plasmids were constructed and cell culture and immune‐biochemical assays were used to examine the effects of the mutation.

Results

We reported a female patient with classical symptoms of WWS and discovered a novel nonsense heterozygous mutation (p.R67X; c.199C>T) in ZC4H2 gene in the patient but not in her parents. The mutation resulted in a 66 amino‐acid truncated ZC4H2 protein. The mutation is located in the key helix domain and it altered the subcellular locations of the mutant ZC4H2 protein. X‐chromosome inactivation (XCI) pattern analysis revealed that the XCI ratio of the proband was 22:78.

Conclusion

Female heterozygous carriers with nonsense mutation with a truncated ZC4H2 protein could lead to the pathogenesis of Wieacker‐Wolff syndrome and our study provides a potential new target for the disease treatment.

Deleterious de novo variants of X-linked ZC4H2 in females cause a variable phenotype with neurogenic arthrogryposis multiplex congenita

Pathogenic variants in the X-linked gene ZC4H2, which encodes a zinc-finger protein, cause an infrequently described syndromic form of arthrogryposis multiplex congenita (AMC) with central and peripheral nervous system involvement. We present genetic and detailed phenotypic information on 23 newly identified families and simplex cases that include 19 affected females from 18 families and 14 affected males from nine families. Of note, the 15 females with deleterious de novo ZC4H2 variants presented with phenotypes ranging from mild to severe, and their clinical features overlapped with those seen in affected males. By contrast, of the nine carrier females with inherited ZC4H2 missense variants that were deleterious in affected male relatives, four were symptomatic. We also compared clinical phenotypes with previously published cases of both sexes and provide an overview on 48 males and 57 females from 42 families. The spectrum of ZC4H2 defects comprises novel and recurrent mostly inherited missense variants in affected males, and de novo splicing, frameshift, nonsense, and partial ZC4H2 deletions in affected females. Pathogenicity of two newly identified missense variants was further supported by studies in zebrafish. We propose ZC4H2 as a good candidate for early genetic testing of males and females with a clinical suspicion of fetal hypo-/akinesia and/or (neurogenic) AMC.

A novel ZC4H2 gene mutation, K209N, in Japanese siblings with arthrogryposis multiplex congenita and intellectual disability: characterization of the K209N mutation and clinical findings

OBJECTIVE

To reveal a molecular lesion in the ZC4H2 gene in a Japanese family with arthrogryposis multiplex congenita (AMC) and intellectual disability (ID), and to characterize clinical features of patients with ZC4H2 gene mutations through a literature review.

PATIENTS

The probands are male siblings. The elder brother is an 11-year-old boy who showed AMC and ID and frequent postprandial hypoglycemia since 3 years of age. The younger brother also showed AMC, ID, and subclinical postprandial hypoglycemia. The boys' mother also showed a minor malformation of the left toes.

METHOD AND RESULT

Using Sanger sequencing, a hemizygous one base substitution designated c.627G > C, which is predicted to substitute asparagine for lysine at amino acid residue 209 (K209N), was identified in the siblings. The mother was heterozygous for this mutation. In silico analysis predicted K209N to be a constituent of a motif required for subcellular localization of the ZC4H2 protein in the nucleus. Transient expression studies of subcellular localization in COS-7 cells showed that compared to the wild-type protein, the transport of the mutant protein into the nucleus was inhibited, thus confirming K209N as a molecular lesion in this family. The literature reviews revealed postprandial hypoglycemia as a new clinical feature that should be considered in ZC4H2 gene-mutation disorders.

CONCLUSION

A Japanese family with AMC and ID caused by a novel ZC4H2 gene mutation was reported. Hypoglycemia should be considered one of the features in this disorder.