Identification of a novel mutation of Platelet-Derived Growth Factor-C (PDGFC) gene in a girl with Non-Syndromic cleft lip and palate.

BACKGROUND: Cleft lip with or without cleft palate (CL/CP) is a prevalent congenital malformation. Approximately 16 candidate loci for CL/CP have been identified in both animal models and humans through association or genetic linkage studies. One of these loci is the platelet-derived growth factor-C (PDGFC) gene. In animal models, a mutation in the PDGFC gene has been shown to lead to CL/CP, with PDGF-C protein serving as a growth factor for mesenchymal cells, playing a crucial role in embryogenesis during the induction of neural crest cells. In this study, we present the identification of a novel frameshift mutation in the PDGFC gene, which we hypothesize to be associated with CL/CP, within a consanguineous Iranian family. CASE PRESENTATION: The proband was a 3-year-old girl with non-syndromic CL/CP. A history of craniofacial clefts was present in her family. Following genetic counseling, karyotype analysis and whole-exome sequencing (WES) were performed. Cytogenetic analysis revealed normal results, while WES analysis showed that the proband carried a homozygous c.546dupA (p.L183fs) mutation in the PDGFC gene. Sanger sequencing confirmed that her parents were carriers of the mutation. CONCLUSION: The c.546dupA (p.L183fs) mutation of PDGFC has not been previously reported and was not found in human genome databases. We speculate that the c.546dupA mutation of the PDGFC gene, identified in the Iranian patient, may be responsible for the phenotype of non-syndromic CL/CP (ns-CL/CP). Further studies are warranted to explore the specific pathogenesis of the PDGFC mutation in ns-CL/CP.

Characterizing Homozygous Variants in Bardet-Biedl Syndrome-Associated Genes Within Iranian Families: Unveiling a Founder Variant in BBS2, c.471G>A.

Bardet-Biedl syndrome (BBS) is a rare inherited ciliopathy disorder characterized by a broad spectrum of clinical symptoms such as retinal dystrophy, obesity, polydactyly, genitourinary and kidney anomalies, learning disability, and hypogonadism. The understanding of the variants involved in BBS-causing genes remains incomplete, highlighting the need for further research to develop a molecular diagnostic strategy for this syndrome. Singleton whole-exome sequencing (WES) was performed on sixteen patients. Our study revealed (1) nine patients carried eight homozygous pathogenic variants with four of them being novel (2) Specifically, a synonymous splicing variant (c.471G > A) in BBS2 gene in six patients with Baloch ethnicity. The identification of runs of homozygosity (ROH) calling was performed using the BCFtools/RoH software on WES data of patients harboring c.471G > A variant. The presence of shared homozygous regions containing the identified variant was confirmed in these patients. In-silico analysis predicted the effect of the c.471G > A variants on BBS2 mRNA splicing. This variant results in disrupted wild-type donor site and intron retention in the mature mRNA. (3) And a deletion of exons 14 to 17 in the BBS1 gene was identified in one patient by Copy-Number Variation (CNV) analysis using the ExomeDepth pipeline. Our results identified the founder variant c.471G > A in the BBS2 gene in the Baloch ethnicity of the Iranian population. This finding can guide the diagnostic approach of this syndrome in future studies.

Bi-allelic genetic variants in the translational GTPases GTPBP1 and GTPBP2 cause a distinct identical neurodevelopmental syndrome.

The homologous genes GTPBP1 and GTPBP2 encode GTP-binding proteins 1 and 2, which are involved in ribosomal homeostasis. Pathogenic variants in GTPBP2 were recently shown to be an ultra-rare cause of neurodegenerative or neurodevelopmental disorders (NDDs). Until now, no human phenotype has been linked to GTPBP1. Here, we describe individuals carrying bi-allelic GTPBP1 variants that display an identical phenotype with GTPBP2 and characterize the overall spectrum of GTP-binding protein (1/2)-related disorders. In this study, 20 individuals from 16 families with distinct NDDs and syndromic facial features were investigated by whole-exome (WES) or whole-genome (WGS) sequencing. To assess the functional impact of the identified genetic variants, semi-quantitative PCR, western blot, and ribosome profiling assays were performed in fibroblasts from affected individuals. We also investigated the effect of reducing expression of CG2017, an ortholog of human GTPBP1/2, in the fruit fly Drosophila melanogaster. Individuals with bi-allelic GTPBP1 or GTPBP2 variants presented with microcephaly, profound neurodevelopmental impairment, pathognomonic craniofacial features, and ectodermal defects. Abnormal vision and/or hearing, progressive spasticity, choreoathetoid movements, refractory epilepsy, and brain atrophy were part of the core phenotype of this syndrome. Cell line studies identified a loss-of-function (LoF) impact of the disease-associated variants but no significant abnormalities on ribosome profiling. Reduced expression of CG2017 isoforms was associated with locomotor impairment in Drosophila. In conclusion, bi-allelic GTPBP1 and GTPBP2 LoF variants cause an identical, distinct neurodevelopmental syndrome. Mutant CG2017 knockout flies display motor impairment, highlighting the conserved role for GTP-binding proteins in CNS development across species.

Lunapark deficiency leads to an autosomal recessive neurodevelopmental phenotype with a degenerative course, epilepsy and distinct brain anomalies.

LNPK encodes a conserved membrane protein that stabilizes the junctions of the tubular endoplasmic reticulum network playing crucial roles in diverse biological functions. Recently, homozygous variants in LNPK were shown to cause a neurodevelopmental disorder (OMIM#618090) in four patients displaying developmental delay, epilepsy and nonspecific brain malformations including corpus callosum hypoplasia and variable impairment of cerebellum. We sought to delineate the molecular and phenotypic spectrum of LNPK-related disorder. Exome or genome sequencing was carried out in 11 families. Thorough clinical and neuroradiological evaluation was performed for all the affected individuals, including review of previously reported patients. We identified 12 distinct homozygous loss-of-function variants in 16 individuals presenting with moderate to profound developmental delay, cognitive impairment, regression, refractory epilepsy and a recognizable neuroimaging pattern consisting of corpus callosum hypoplasia and signal alterations of the forceps minor ('ear-of-the-lynx' sign), variably associated with substantia nigra signal alterations, mild brain atrophy, short midbrain and cerebellar hypoplasia/atrophy. In summary, we define the core phenotype of LNPK-related disorder and expand the list of neurological disorders presenting with the 'ear-of-the-lynx' sign suggesting a possible common underlying mechanism related to endoplasmic reticulum-phagy dysfunction.

Production of Duchenne muscular dystrophy cellular model using CRISPR-Cas9 exon deletion strategy.

Duchenne Muscular Dystrophy (DMD) is a progressive muscle wasting disorder caused by loss-of-function mutations in the dystrophin gene. Although the search for a definitive cure has failed to date, extensive efforts have been made to introduce effective therapeutic strategies. Gene editing technology is a great revolution in biology, having an immediate application in the generation of research models. DMD muscle cell lines are reliable sources to evaluate and optimize therapeutic strategies, in-depth study of DMD pathology, and screening the effective drugs. However, only a few immortalized muscle cell lines with DMD mutations are available. In addition, obtaining muscle cells from patients also requires an invasive muscle biopsy. Mostly DMD variants are rare, making it challenging to identify a patient with a particular mutation for a muscle biopsy. To overcome these challenges and generate myoblast cultures, we optimized a CRISPR/Cas9 gene editing approach to model the most common DMD mutations that include approximately 28.2% of patients. GAP-PCR and sequencing results show the ability of the CRISPR-Cas9 system to efficient deletion of mentioned exons. We showed producing truncated transcript due to the targeted deletion by RT-PCR and sequencing. Finally, mutation-induced disruption of dystrophin protein expression was confirmed by western blotting. All together, we successfully created four immortalized DMD muscle cell lines and showed the efficacy of the CRISPR-Cas9 system for the generation of immortalized DMD cell models with the targeted deletions.

Broadening the phenotypic and molecular spectrum of FINCA syndrome: Biallelic NHLRC2 variants in 15 novel individuals.

FINCA syndrome [MIM: 618278] is an autosomal recessive multisystem disorder characterized by fibrosis, neurodegeneration and cerebral angiomatosis. To date, 13 patients from nine families with biallelic NHLRC2 variants have been published. In all of them, the recurrent missense variant p.(Asp148Tyr) was detected on at least one allele. Common manifestations included lung or muscle fibrosis, respiratory distress, developmental delay, neuromuscular symptoms and seizures often followed by early death due to rapid disease progression.Here, we present 15 individuals from 12 families with an overlapping phenotype associated with nine novel NHLRC2 variants identified by exome analysis. All patients described here presented with moderate to severe global developmental delay and variable disease progression. Seizures, truncal hypotonia and movement disorders were frequently observed. Notably, we also present the first eight cases in which the recurrent p.(Asp148Tyr) variant was not detected in either homozygous or compound heterozygous state.We cloned and expressed all novel and most previously published non-truncating variants in HEK293-cells. From the results of these functional studies, we propose a potential genotype-phenotype correlation, with a greater reduction in protein expression being associated with a more severe phenotype.Taken together, our findings broaden the known phenotypic and molecular spectrum and emphasize that NHLRC2-related disease should be considered in patients presenting with intellectual disability, movement disorders, neuroregression and epilepsy with or without pulmonary involvement.

New advancements in CRISPR based gene therapy of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is caused by the dystrophin gene mutations and is one of the most common and lethal human hereditary disorders. A novel therapeutic approach using CRISPR technology has gained attention in the treatment of DMD. Gene replacement strategies are being proposed as a promising therapeutic option to compensate the loss of function mutations. Although, the large size of the dystrophin gene and the limitations of the existing gene replacement approach, could mean the gene delivery of shortened versions of dystrophin such as midystrophin and microdystrophins. There are also other approaches: including Targeted removal of dystrophin exons to restore the reading-frame; Dual sgRNA-directed DMD exon deletion, CRISPR-SKIP strategy; reframing of dystrophin using Prime Editing technology; exon removal using twin prime technology; TransCRISTI technology to targeted exon integration into dystrophin gene. Here we provide an overview of recent progresses in dystrophin gene editing using updated versions of CRISPR to introduce novel opportunities in DMD gene therapy. Overall, the novel CRISPR based technologies are improving and expanding to allow the application of more precise gene editing for the treatment of DMD.

TMEM263: a novel candidate gene implicated in human autosomal recessive severe lethal skeletal dysplasia.

INTRODUCTION: Skeletal dysplasia is a common, clinically and genetically heterogeneous disorder in the human population. An increasing number of different genes are being identified causing this disorder. We used whole exome sequencing (WES) for detection of skeletal dysplasia causing mutation in a fetus affected to severe lethal skeletal dysplasia. PATIENT: Fetus was assessed by ultrasonography in second trimester of pregnancy. He suffers from severe rhizomelic dysplasia and also pathologic shortening of ribs. WES was applied to finding of causal mutation. Furthermore, bioinformatics analysis was performed to predict mutation impact. RESULTS: Whole exome sequencing (WES) identified a homozygous frameshift mutation in the TMEM263 gene in a fetus with severe lethal skeletal dysplasia. Mutations of this gene have been previously identified in dwarf chickens, but this is the first report of involvement of this gene in human skeletal dysplasia. This gene plays a key role in the growth hormone signaling pathway. CONCLUSION: TMEM263 can be considered as a new gene responsible for skeletal dysplasia. Given the complications observed in the affected fetus, the mutation of this gene appears to produce much more intense complications than that found in chickens and is likely to play a more important role in bone development in human.

TMEM218 dysfunction causes ciliopathies, including Joubert and Meckel syndromes.

The Joubert-Meckel syndrome spectrum is a continuum of recessive ciliopathy conditions caused by primary cilium dysfunction. The primary cilium is a microtubule-based, antenna-like organelle that projects from the surface of most human cell types, allowing them to respond to extracellular signals. The cilium is partitioned from the cell body by the transition zone, a known hotspot for ciliopathy-related proteins. Despite years of Joubert syndrome (JBTS) gene discovery, the genetic cause cannot be identified in up to 30% of individuals with JBTS, depending on the cohort, sequencing method, and criteria for pathogenic variants. Using exome and targeted sequencing of 655 families with JBTS, we identified three individuals from two families harboring biallelic, rare, predicted-deleterious missense TMEM218 variants. Via MatchMaker Exchange, we identified biallelic TMEM218 variants in four additional families with ciliopathy phenotypes. Of note, four of the six families carry missense variants affecting the same highly conserved amino acid position 115. Clinical features included the molar tooth sign (N = 2), occipital encephalocele (N = 5, all fetuses), retinal dystrophy (N = 4, all living individuals), polycystic kidneys (N = 2), and polydactyly (N = 2), without liver involvement. Combined with existing functional data linking TMEM218 to ciliary transition zone function, our human genetic data make a strong case for TMEM218 dysfunction as a cause of ciliopathy phenotypes including JBTS with retinal dystrophy and Meckel syndrome. Identifying all genetic causes of the Joubert-Meckel spectrum enables diagnostic testing, prognostic and recurrence risk counseling, and medical monitoring, as well as work to delineate the underlying biological mechanisms and identify targets for future therapies.

Investigating the association of Lamotrigine and Phenytoin-induced Stevens-Johnson syndrome/Toxic Epidermal Necrolysis with HLA-B*1502 in Iranian population.

Previous studies have found an association between HLA-B*1502 allele and lamotrigine-induced Stevens-Johnson syndrome (SJS)/ toxic epidermal necrosis (TEN) spectrum in Han Chinese populations. This study aims to investigate the association between HLA-B*1502 and lamotrigine- or phenytoin- induced SJS/TEN in an Iranian population. The medical records of twenty-eight lamotrigine-induced SJS/TEN patients and twenty-five lamotrigine-tolerant controls as well as eight phenytoin-induced SJS/TEN and twelve phenytoin-tolerant controls were extracted between March 2013 and March 2019 from the university hospitals in Mashhad, Iran. The presence of HLA-B*1502 allele was determined using real-time polymerase chain reaction (PCR). Among lamotrigine-induced patients with SJS/TEN, 11 (39.3%) patients tested positive for the HLA-B*1502 while only 3 (12.0%) of the lamotrigine-tolerant controls tested positive for this allele. The risk of lamotrigine-induced SJS/TEN was significantly higher in patients with HLA-B*1502, with an odds ratio (OR) of 4.74 [95% confidence interval (CI) 1.14-19.73, p = 0.032]. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HLA-B*1502 for lamotrigine-induced SJS/TEN was 39.29%, 88.00%, 78.57% and 56.41%, respectively. The HLA-B*1502 allele was present in 2 (25.0%) of phenytoin-induced SJS/TEN cases and 5 (41.7%) of the phenytoin-tolerant controls tested positive for HLA-B*1502 allele. The risk of phenytoin-induced SJS/TEN was not higher in the patients with HLA-B*1502 (OR = 0.467 [95% confidence interval (CI) 0.065-3.34, p = 0.642]). Lamotrigine-induced SJS/TEN is associated with HLA-B*1502 allele in an Iranian population but this is not the case for phenytoin-induced SJS/TEN.

Investigation of MYO15A and MYO7A Mutations in Iranian Patients with Nonsyndromic Hearing Loss.

BACKGROUND: Hearing loss (HL) is the most common sensory disorder in humans, which affects individuals in both inherited and acquired forms. MYO15A and MYO7A gene mutations have a significant role in the development of deafness. In this study, we assessed the prevalence of MYO15A and MYO7A mutations in one hundred non-relative deaf Iranians. Materials and methods: The existence of MYO15A and MYO7A mutations were assessed using the tetra-primer ARMS-PCR method, High Resolution Melting (HRM) and sequencing method. Results: A heterozygote missense mutation, p.V2135L (c.6403G > T) in the MYO15A gene, was found in a patient using the sequencing method. Conclusion: These results explain the negligible prevalence of selected mutations among Iranian patients. Identifying common mutations in patients of an ethnic group can reduce the financial costs and time needed for identifying the causes of deafness.

G-CSF augments the neuroprotective effect of conditioned medium of dental pulp stem cells against hypoxic neural injury in SH-SY5Y cells.

Objectives: Dental pulp stem cells (DPSCs) can differentiate into functional neurons and have the potential for cell therapy in neurological diseases. Granulocyte colony-stimulating factor (G-CSF) is a glycoprotein family shown neuroprotective effect in models of nerve damage.we evaluated the protective effects of G-CSF, conditioned media from DPSCs (DPSCs-CM) and conditioned media from transfected DPSCs with plasmid encoding G-CSF (DPSC-CMT) on SH-SY5Y exposed to CoCl2 as a model of hypoxia-induced neural damage. Materials and Methods: SH-SY5Y exposed to CoCl2 were treated with DPSCs-CM, G-CSF, simultaneous combination of DPSCs-CM and G-CSF and finally DPSC-CMT. Cell viability and apoptosis were determined by resazurin (or lactate dehydrogenase (LDH) assay alternatively) and propidium iodide (PI) staining. Western blot analysis was performed to detect changes in apoptotic protein levels. The interleukin-6 and interleukin-10 IL6/IL10 levels were measured with Enzyme-Linked Immunosorbent Assay (ELISA). Results: DPSCs-CM and G-CSF were able to significantly protect SH-SY5Y against neural cell damage caused by CoCl2 according to resazurin and LDH analysis. Also, the percentage of apoptotic cells decreased when SH-SY5Y were treated with DPSCs-CM and G-CSF simultaneously. After transfection of DPSCs with G-CSF plasmid, DPSC-CMT could significantly improve the protection. The amount of ß-catenin, cleaved PARP and caspase-3 were significantly decreased and the expression of survivin was considerably increased when hypoxic SH-SY5Y treated with DPSCs-CM plus G-CSF according to Western blot. Decreased level of IL-6/IL-10, which exposed to CoCl2, after treatment with DPSCs-CM indicated the suppression of inflammatory mediators. Conclusion: Combination therapy of G-CSF and DPSCs-CM improved the protective activity.

PLA2G6 gene mutation and infantile neuroaxonal degeneration; report of three cases from Iran.

OBJECTIVES: Infantile neuroaxonal degeneration (INAD) is a rare subgroup of neurodegeneration with brain iron accumulation (NBIA) disorders. This progressive disorder may develop during the early years of life. Affected individuals mostly manifest developmental delay and/or psychomotor regression as well as other neurological deficits. In the present study, we discussed 3 INAD patients diagnosed before the age of 10 by using Whole-Exome Sequencing (WES). MATERIALS AND METHODS: We evaluated 3 pediatric patients with clinical phenotypes of INAD who underwent WES. Sanger sequencing was performed for co-segregation analysis of the variants in the families. An in-silico study was conducted for identification of the molecular function of the identified genetic variants in the PLA2G6 gene. RESULTS: We detected three novel genetic variants in the PLA2G6 gene including a homozygous missense (NM_003560.2; c.1949T>C; p.Phe650Ser), a splicing (NM_001349864; c.1266-1G>A) and a frameshift variant (NM_003560.4; c.1547_1548dupCG; p.Gly517ArgfsTer29). Since the variants were not previously reported in literature or population databases, we performed in-silico studies for these variants and demonstrated their potential pathogenicity. CONCLUSION: The current study reports novel genetic variants in the PLA2G6 gene in the Iranian population, emphasizing the importance of high-throughput genetic testing in rare diseases.

The worldwide frequency of MYO15A gene mutations in patients with non-syndromic hearing loss: A meta-analysis.

MYO15A is the third most crucial gene in hereditary sensorineural hearing loss after GJB2 and SLC26A4. In the present study, we reviewed the prevalence of MYO15A mutations in patients with autosomal recessive non-syndromic hearing loss (ARNSHL). In this meta-analysis, we conducted a search of PubMed, Web of Science, Excerpta Medica Database, and Scopus, and identified the articles up to September 2019 without any time limit. Two investigators independently selected the relevant papers and extracted the required information. A total of 44 case-control and case series studies were considered, and 4176 patients and 3706 healthy individuals, as the control group, were included. The pooled frequency of MYO15A mutations between patients suffering from ARNSHL was calculated as 6.2% (95% CI: 4.9-7.8, P-value<0.001). There was heterogeneity between our studies (P-value<0.001, I2=58.1%); therefore, the random-effects model was utilized for analysis. Given the results, in many countries, the MYO15A gene has a significant contribution to hearing loss. Moreover, in several regions, specific dominant mutations in this gene have been reported. Therefore, the ethnic background should be considered to investigate the mutations of the MYO15A gene.

Early-infantile onset epilepsy and developmental delay caused by bi-allelic GAD1 variants.

Gamma-aminobutyric acid (GABA) and glutamate are the most abundant amino acid neurotransmitters in the brain. GABA, an inhibitory neurotransmitter, is synthesized by glutamic acid decarboxylase (GAD). Its predominant isoform GAD67, contributes up to ∼90% of base-level GABA in the CNS, and is encoded by the GAD1 gene. Disruption of GAD1 results in an imbalance of inhibitory and excitatory neurotransmitters, and as Gad1-/- mice die neonatally of severe cleft palate, it has not been possible to determine any potential neurological dysfunction. Furthermore, little is known about the consequence of GAD1 disruption in humans. Here we present six affected individuals from six unrelated families, carrying bi-allelic GAD1 variants, presenting with developmental and epileptic encephalopathy, characterized by early-infantile onset epilepsy and hypotonia with additional variable non-CNS manifestations such as skeletal abnormalities, dysmorphic features and cleft palate. Our findings highlight an important role for GAD1 in seizure induction, neuronal and extraneuronal development, and introduce GAD1 as a new gene associated with developmental and epileptic encephalopathy.

NR1H4-related Progressive Familial Intrahepatic Cholestasis 5: Further Evidence for Rapidly Progressive Liver Failure.

Pathogenic sequence variants in the nuclear bile acid receptor FXR, encoded by NR1H4, have been reported in a small number of children with low-γ-glutamyl transferase (GGT) cholestasis progressing to liver failure. We describe 3 additional children from 2 unrelated families with cholestasis and liver failure because of pathologic variants in NR1H4. One patient underwent liver transplantation and has had good clinical outcomes in 6 years of follow-up. Although that patient has biochemical evidence of increased bile acid synthetic activity, he has not experienced post-transplant diarrhea or allograft steatosis, as has been reported among other transplanted patients.

Loss of UGP2 in brain leads to a severe epileptic encephalopathy, emphasizing that bi-allelic isoform-specific start-loss mutations of essential genes can cause genetic diseases.

Developmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders, resulting in early-onset, therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy, severe developmental delay, progressive microcephaly, visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent, homozygous variant (chr2:64083454A > G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform, which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells, leading to altered glycogen metabolism, upregulated unfolded protein response and premature neuronal differentiation, as modeled during pluripotent stem cell differentiation in vitro. In contrast, the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly, it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease, even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies.

Targeted Mutation Analysis of the SLC26A4, MYO6, PJVK and CDH23 Genes in Iranian Patients with AR Nonsyndromic Hearing Loss.

BACKGROUND: Hearing loss (HL) is the most prevalent sensory disorder. The over 100 genes implicated in autosomal recessive nonsyndromic hearing loss (ARNSHL) makes it difficult to analyze and determine the accurate genetic causes of hearing loss. We sought to de?ne the frequency of seven hearing loss-Causing causing genetic Variants in four genes in an Iranian population with hearing loss. MATERIALS AND METHODS: One hundred ARNSHL patients with normal GJB2/GJB6 genes were included, and targeted mutations in SLC26A4, MYO6, PJVK and CDH23 genes were analyzed by ARMS-PCR. The negative and positive results were confirmed by the Sanger sequencing. RESULTS: We found only two mutations, one in MYO6 (c.554-1 G > A) gene and another in PJVK (c.547C > T). CONCLUSION: c.554-1G > A and c.547C > T mutations are responsible for 1% each of the Iranian ARNSHL patients. These genes are not a frequent cause of ARNSHL in an Iranian population.

Genetic, Phenotypic, and Interferon Biomarker Status in ADAR1-Related Neurological Disease.

We investigated the genetic, phenotypic, and interferon status of 46 patients from 37 families with neurological disease due to mutations in ADAR1. The clinicoradiological phenotype encompassed a spectrum of Aicardi-Goutières syndrome, isolated bilateral striatal necrosis, spastic paraparesis with normal neuroimaging, a progressive spastic dystonic motor disorder, and adult-onset psychological difficulties with intracranial calcification. Homozygous missense mutations were recorded in five families. We observed a p.Pro193Ala variant in the heterozygous state in 22 of 23 families with compound heterozygous mutations. We also ascertained 11 cases from nine families with a p.Gly1007Arg dominant-negative mutation, which occurred de novo in four patients, and was inherited in three families in association with marked phenotypic variability. In 50 of 52 samples from 34 patients, we identified a marked upregulation of type I interferon-stimulated gene transcripts in peripheral blood, with a median interferon score of 16.99 (interquartile range [IQR]: 10.64-25.71) compared with controls (median: 0.93, IQR: 0.57-1.30). Thus, mutations in ADAR1 are associated with a variety of clinically distinct neurological phenotypes presenting from early infancy to adulthood, inherited either as an autosomal recessive or dominant trait. Testing for an interferon signature in blood represents a useful biomarker in this context.

PRUNE is crucial for normal brain development and mutated in microcephaly with neurodevelopmental impairment.

PRUNE is a member of the DHH (Asp-His-His) phosphoesterase protein superfamily of molecules important for cell motility, and implicated in cancer progression. Here we investigated multiple families from Oman, India, Iran and Italy with individuals affected by a new autosomal recessive neurodevelopmental and degenerative disorder in which the cardinal features include primary microcephaly and profound global developmental delay. Our genetic studies identified biallelic mutations of PRUNE1 as responsible. Our functional assays of disease-associated variant alleles revealed impaired microtubule polymerization, as well as cell migration and proliferation properties, of mutant PRUNE. Additionally, our studies also highlight a potential new role for PRUNE during microtubule polymerization, which is essential for the cytoskeletal rearrangements that occur during cellular division and proliferation. Together these studies define PRUNE as a molecule fundamental for normal human cortical development and define cellular and clinical consequences associated with PRUNE mutation.