A novel ICK mutation causes ciliary disruption and lethal endocrine-cerebro-osteodysplasia syndrome

Background: Endocrine-cerebro-osteodysplasia (ECO) syndrome [MIM:612651] caused by a recessive mutation (p.R272Q) in Intestinal cell kinase (ICK) shows significant clinical overlap with ciliary disorders. Similarities are strongest between ECO syndrome, the Majewski and Mohr-Majewski short-rib thoracic dysplasia (SRTD) with polydactyly syndromes, and hydrolethalus syndrome. In this study, we present a novel homozygous ICK mutation in a fetus with ECO syndrome and compare the effect of this mutation with the previously reported ICK variant on ciliogenesis and cilium morphology. Results: Through homozygosity mapping and whole-exome sequencing, we identified a second variant (c.358G\u3eT; p.G120C) in ICK in a Turkish fetus presenting with ECO syndrome. In vitro studies of wild-type and mutant mRFP-ICK (p.G120C and p.R272Q) revealed that, in contrast to the wild-type protein that localizes along the ciliary axoneme and/or is present in the ciliary base, mutant proteins rather enrich in the ciliary tip. In addition, immunocytochemistry revealed a decreased number of cilia in ICK p.R272Q-affected cells. Conclusions: Through identification of a novel ICK mutation, we confirm that disruption of ICK causes ECO syndrome, which clinically overlaps with the spectrum of ciliopathies. Expression of ICK-mutated proteins result in an abnormal ciliary localization compared to wild-type protein. Primary fibroblasts derived from an individual with ECO syndrome display ciliogenesis defects. In aggregate, our findings are consistent with recent reports that show that ICK regulates ciliary biology in vitro and in mice, confirming that ECO syndrome is a severe ciliopathy

Ermin deficiency leads to compromised myelin, inflammatory milieu, and susceptibility to demyelinating insult

Ermin is an actin-binding protein found almost exclusively in the central nervous system (CNS) as a component of myelin sheaths. Although Ermin has been predicted to play a role in the formation and stability of myelin sheaths, this has not been directly examined in vivo. Here, we show that Ermin is essential for myelin sheath integrity and normal saltatory conduction. Loss of Ermin in mice caused de-compacted and fragmented myelin sheaths and led to slower conduction along with progressive neurological deficits. RNA sequencing of the corpus callosum, the largest white matter structure in the CNS, pointed to inflammatory activation in aged Ermin-deficient mice, which was corroborated by increased levels of microgliosis and astrogliosis. The inflammatory milieu and myelin abnormalities were further associated with increased susceptibility to immune-mediated demyelination insult in Ermin knockout mice. Supporting a possible role of Ermin deficiency in inflammatory white matter disorders, a rare inactivating mutation in the ERMN gene was identified in multiple sclerosis patients. Our findings demonstrate a critical role for Ermin in maintaining myelin integrity. Given its near-exclusive expression in myelinating oligodendrocytes, Ermin deficiency represents a compelling “inside-out” model of inflammatory dysmyelination and may offer a new paradigm for the development of myelin stability-targeted therapies

Loss-of-function mutations in UDP-Glucose 6-Dehydrogenase cause recessive developmental epileptic encephalopathy

AbstractDevelopmental epileptic encephalopathies are devastating disorders characterized by intractable epileptic seizures and developmental delay. Here, we report an allelic series of germline recessive mutations in UGDH in 36 cases from 25 families presenting with epileptic encephalopathy with developmental delay and hypotonia. UGDH encodes an oxidoreductase that converts UDP-glucose to UDP-glucuronic acid, a key component of specific proteoglycans and glycolipids. Consistent with being loss-of-function alleles, we show using patients’ primary fibroblasts and biochemical assays, that these mutations either impair UGDH stability, oligomerization, or enzymatic activity. In vitro, patient-derived cerebral organoids are smaller with a reduced number of proliferating neuronal progenitors while mutant ugdh zebrafish do not phenocopy the human disease. Our study defines UGDH as a key player for the production of extracellular matrix components that are essential for human brain development. Based on the incidence of variants observed, UGDH mutations are likely to be a frequent cause of recessive epileptic encephalopathy.</jats:p

Loss-of-function mutations in UDP-Glucose 6-Dehydrogenase cause recessive developmental epileptic encephalopathy

Developmental epileptic encephalopathies are devastating disorders characterized by intractable epileptic seizures and developmental delay. Here, we report an allelic series of germline recessive mutations in UGDH in 36 cases from 25 families presenting with epileptic encephalopathy with developmental delay and hypotonia. UGDH encodes an oxidoreductase that converts UDP-glucose to UDP-glucuronic acid, a key component of specific proteoglycans and glycolipids. Consistent with being loss-of-function alleles, we show using patients’ primary fibroblasts and biochemical assays, that these mutations either impair UGDH stability, oligomerization, or enzymatic activity. In vitro, patient-derived cerebral organoids are smaller with a reduced number of proliferating neuronal progenitors while mutant ugdh zebrafish do not phenocopy the human disease. Our study defines UGDH as a key player for the production of extracellular matrix components that are essential for human brain development. Based on the incidence of variants observed, UGDH mutations are likely to be a frequent cause of recessive epileptic encephalopathy

Cenani-Lenz syndactyly syndrome - a case report of a family with isolated syndactyly

Abstract Background Cenani-Lenz Syndactyly (CLS) syndrome is a rare autosomal recessive disorder characterized by syndactyly and oligodactyly of fingers and toes, disorganization and fusion of metacarpals, metatarsals and phalanges, radioulnar synostosis and mesomelic shortness of the limbs, with lower limbs usually being much less affected than upper limbs. Case presentation we report here two patients, born to consanguineous Sri Lankan parents, present with bilateral postaxial oligodactyly limited to upper limbs. While the proband has no noticeable facial dysmorphism, renal impairments or cognitive impairments, his affected sister displays a few mild facial dysmorphic features. Whole exome sequencing of the proband showed a novel deleterious homozygous mutation (c.1348A > G) in the LRP4 gene, resulting in an Ile450-to-Val (I450V) substitution. Conclusion This recessive mutation in LRP4 confirmed the diagnosis of CLS syndrome in two patients present with isolated hand syndactyly. This is the first reported case of CLS syndrome in a family of Sri Lankan origin

Mutation in TWINKLE in a Large Iranian Family with Progressive External Ophthalmoplegia, Myopathy, Dysphagia and Dysphonia, and Behavior Change

BACKGROUND: TWINKLE (c10orf2) gene is responsible for autosomal dominant progressive external ophthalmoplegia (PEO). In rare cases, additional features such as muscle weakness, peripheral neuropathy, ataxia, cardiomyopathy, dysphagia, dysphonia, cataracts, depression, dementia, parkinsonism, and hearing loss have been reported in association with heterozygous mutations of the TWINKLE gene. METHODS: We have studied a large Iranian family with myopathy, dysphonia, dysphagia, and behavior change in addition to PEO in affected members. RESULTS: We identified a missense mutation c.1121G > A in the c10orf2 gene in all affected members. Early death is a novel feature seen in affected members of this family that has not been reported to date. CONCLUSION: The association of PEO, myopathy, dysphonia, dysphagia, behavior change and early death has not been previously reported in the literature or other patients with this mutatio

A novel nonsense ATP2C1 mutation causes Hailey-Hailey disease in a Tunisian family

Background: Hailey-Hailey disease (HHD) is an autosomal dominant blistering skin disorder that manifests in the third to fourth decade of life. The ATP2C1 has been identified as the pathogenic gene of this disease since 2000. Materials and Methods: We report here a three generations Tunisian pedigree, where almost all males are severely affected and present with complete penetrance of HHD, while only one female shows a mild disease’s phenotype in her fourth decade. A molecular study using Whole exome sequencing and direct sequencing was performed to this family. Results: By whole exome sequencing and direct DNA sequencing, a novel nonsense mutation in ATP2C1 (c.2698A>T; p.Lys900Ter) was identified in all patients, supporting that alterations in ATP2C1 are causative of HHD. Unexpectedly, this mutation was found in one female who was initially not diagnosed for HHD. Our observations would be in line with incomplete penetrance and variable expressivity between male and female of this disease, or evidence for genetic modifiers. Conclusion: We report here a novel nonsense heterozygous mutation in ATP2C1 gene in 5 patients with HHD. Interestingly, one woman carries the nonsense ATP2C1 mutation but displays a mild phenotype of HHD. This could indicate a variation in pattern and expressivity between male and female developing HHD phenotype which should be considered when providing genetic counselling to family members carrying such mutations

Figure S1 from Voltage-gated sodium channel gene repertoire of lampreys: gene duplications, tissue-specific expression and discovery of a long-lost gene

Studies of the voltage-gated sodium (Nav) channels of extant gnathostomes have made it possible to deduce that ancestral gnathostomes possessed four voltage-gated sodium channel genes derived from a single ancestral chordate gene following two rounds of genome duplication early in vertebrates. We investigated the Nav gene family in two species of lampreys (the Japanese lamprey, <i>Lethenteron japonicum</i> and sea lamprey, <i>Petromyzon marinus</i>) (jawless vertebrates—agnatha) and compared them with those of basal vertebrates to better understand the origin of Nav genes in vertebrates. We noted six Nav genes in both lamprey species but orthology with gnathostome (jawed vertebrate) channels was inconclusive. Surprisingly, the Nav2 gene, ubiquitously found in invertebrates and believed to have been lost in vertebrates, is present in lampreys, elephant shark (<i>Callorhinchus milii</i>) and coelacanth (<i>Latimeria chalumnae</i>). Despite repeated duplication of the Nav1 family in vertebrates, Nav2 is only in single copy in those vertebrates in which it is retained, and was independently lost in ray-finned fishes and tetrapods. Of the other five Nav channel genes, most were expressed in brain, one in brain and heart, and one exclusively in skeletal muscle. Invertebrates do not express Nav channel genes in muscle. Thus, early in the vertebrate lineage Nav channels began to diversify and different genes began to express in heart and muscle

Supplementary Table SI from Voltage-gated sodium channel gene repertoire of lampreys: gene duplications, tissue-specific expression and discovery of a long-lost gene

Studies of the voltage-gated sodium (Nav) channels of extant gnathostomes have made it possible to deduce that ancestral gnathostomes possessed four voltage-gated sodium channel genes derived from a single ancestral chordate gene following two rounds of genome duplication early in vertebrates. We investigated the Nav gene family in two species of lampreys (the Japanese lamprey, <i>Lethenteron japonicum</i> and sea lamprey, <i>Petromyzon marinus</i>) (jawless vertebrates—agnatha) and compared them with those of basal vertebrates to better understand the origin of Nav genes in vertebrates. We noted six Nav genes in both lamprey species but orthology with gnathostome (jawed vertebrate) channels was inconclusive. Surprisingly, the Nav2 gene, ubiquitously found in invertebrates and believed to have been lost in vertebrates, is present in lampreys, elephant shark (<i>Callorhinchus milii</i>) and coelacanth (<i>Latimeria chalumnae</i>). Despite repeated duplication of the Nav1 family in vertebrates, Nav2 is only in single copy in those vertebrates in which it is retained, and was independently lost in ray-finned fishes and tetrapods. Of the other five Nav channel genes, most were expressed in brain, one in brain and heart, and one exclusively in skeletal muscle. Invertebrates do not express Nav channel genes in muscle. Thus, early in the vertebrate lineage Nav channels began to diversify and different genes began to express in heart and muscle