Biallelic variants in TMEM222 cause a new autosomal recessive neurodevelopmental disorder.

PURPOSE: To elucidate the novel molecular cause in families with a new autosomal recessive neurodevelopmental disorder. METHODS: A combination of exome sequencing and gene matching tools was used to identify pathogenic variants in 17 individuals. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and subcellular localization studies were used to characterize gene expression profile and localization. RESULTS: Biallelic variants in the TMEM222 gene were identified in 17 individuals from nine unrelated families, presenting with intellectual disability and variable other features, such as aggressive behavior, shy character, body tremors, decreased muscle mass in the lower extremities, and mild hypotonia. We found relatively high TMEM222 expression levels in the human brain, especially in the parietal and occipital cortex. Additionally, subcellular localization analysis in human neurons derived from induced pluripotent stem cells (iPSCs) revealed that TMEM222 localizes to early endosomes in the synapses of mature iPSC-derived neurons. CONCLUSION: Our findings support a role for TMEM222 in brain development and function and adds variants in the gene TMEM222 as a novel underlying cause of an autosomal recessive neurodevelopmental disorder.

Biallelic loss of function variants in PPP1R21 cause a neurodevelopmental syndrome with impaired endocytic function.

Next-generation sequencing (NGS) has been instrumental in solving the genetic basis of rare inherited diseases, especially neurodevelopmental syndromes. However, functional workup is essential for precise phenotype definition and to understand the underlying disease mechanisms. Using whole exome (WES) and whole genome sequencing (WGS) in four independent families with hypotonia, neurodevelopmental delay, facial dysmorphism, loss of white matter, and thinning of the corpus callosum, we identified four previously unreported homozygous truncating PPP1R21 alleles: c.347delT p.(Ile116Lysfs*25), c.2170_2171insGGTA p.(Ile724Argfs*8), c.1607dupT p.(Leu536Phefs*7), c.2063delA p.(Lys688Serfs*26) and found that PPP1R21 was absent in fibroblasts of an affected individual, supporting the allele's loss of function effect. PPP1R21 function had not been studied except that a large scale affinity proteomics approach suggested an interaction with PIBF1 defective in Joubert syndrome. Our co-immunoprecipitation studies did not confirm this but in contrast defined the localization of PPP1R21 to the early endosome. Consistent with the subcellular expression pattern and the clinical phenotype exhibiting features of storage diseases, we found patient fibroblasts exhibited a delay in clearance of transferrin-488 while uptake was normal. In summary, we delineate a novel neurodevelopmental syndrome caused by biallelic PPP1R21 loss of function variants, and suggest a role of PPP1R21 within the endosomal sorting process or endosome maturation pathway.

Pathogenic Variants in PIGG Cause Intellectual Disability with Seizures and Hypotonia.

Glycosylphosphatidylinositol (GPI) is a glycolipid that anchors >150 various proteins to the cell surface. At least 27 genes are involved in biosynthesis and transport of GPI-anchored proteins (GPI-APs). To date, mutations in 13 of these genes are known to cause inherited GPI deficiencies (IGDs), and all are inherited as recessive traits. IGDs mainly manifest as intellectual disability, epilepsy, coarse facial features, and multiple organ anomalies. These symptoms are caused by the decreased surface expression of GPI-APs or by structural abnormalities of GPI. Here, we present five affected individuals (from two consanguineous families from Egypt and Pakistan and one non-consanguineous family from Japan) who show intellectual disability, hypotonia, and early-onset seizures. We identified pathogenic variants in PIGG, a gene in the GPI pathway. In the consanguineous families, homozygous variants c.928C>T (p.Gln310(∗)) and c.2261+1G>C were found, whereas the Japanese individual was compound heterozygous for c.2005C>T (p.Arg669Cys) and a 2.4 Mb deletion involving PIGG. PIGG is the enzyme that modifies the second mannose with ethanolamine phosphate, which is removed soon after GPI is attached to the protein. Physiological significance of this transient modification has been unclear. Using B lymphoblasts from affected individuals of the Egyptian and Japanese families, we revealed that PIGG activity was almost completely abolished; however, the GPI-APs had normal surface levels and normal structure, indicating that the pathogenesis of PIGG deficiency is not yet fully understood. The discovery of pathogenic variants in PIGG expands the spectrum of IGDs and further enhances our understanding of this etiopathogenic class of intellectual disability.

Autosomal-Recessive Mutations in AP3B2, Adaptor-Related Protein Complex 3 Beta 2 Subunit, Cause an Early-Onset Epileptic Encephalopathy with Optic Atrophy.

Early-onset epileptic encephalopathy (EOEE) represents a heterogeneous group of severe disorders characterized by seizures, interictal epileptiform activity with a disorganized electroencephalography background, developmental regression or retardation, and onset before 1 year of age. Among a cohort of 57 individuals with epileptic encephalopathy, we ascertained two unrelated affected individuals with EOEE associated with developmental impairment and autosomal-recessive variants in AP3B2 by means of whole-exome sequencing. The targeted sequencing of AP3B2 in 86 unrelated individuals with EOEE led to the identification of an additional family. We gathered five additional families with eight affected individuals through the Matchmaker Exchange initiative by matching autosomal-recessive mutations in AP3B2. Reverse phenotyping of 12 affected individuals from eight families revealed a homogeneous EOEE phenotype characterized by severe developmental delay, poor visual contact with optic atrophy, and postnatal microcephaly. No spasticity, albinism, or hematological symptoms were reported. AP3B2 encodes the neuron-specific subunit of the AP-3 complex. Autosomal-recessive variations of AP3B1, the ubiquitous isoform, cause Hermansky-Pudlak syndrome type 2. The only isoform for the δ subunit of the AP-3 complex is encoded by AP3D1. Autosomal-recessive mutations in AP3D1 cause a severe disorder cumulating the symptoms of the AP3B1 and AP3B2 defects.

Exome sequencing reveals pathogenic mutations in 91 strains of mice with Mendelian disorders.

Spontaneously arising mouse mutations have served as the foundation for understanding gene function for more than 100 years. We have used exome sequencing in an effort to identify the causative mutations for 172 distinct, spontaneously arising mouse models of Mendelian disorders, including a broad range of clinically relevant phenotypes. To analyze the resulting data, we developed an analytics pipeline that is optimized for mouse exome data and a variation database that allows for reproducible, user-defined data mining as well as nomination of mutation candidates through knowledge-based integration of sample and variant data. Using these new tools, putative pathogenic mutations were identified for 91 (53%) of the strains in our study. Despite the increased power offered by potentially unlimited pedigrees and controlled breeding, about half of our exome cases remained unsolved. Using a combination of manual analyses of exome alignments and whole-genome sequencing, we provide evidence that a large fraction of unsolved exome cases have underlying structural mutations. This result directly informs efforts to investigate the similar proportion of apparently Mendelian human phenotypes that are recalcitrant to exome sequencing.

ASSESSMENT OF KNOWLEDGE, ATTITUDE AND PRACTICE TOWARDS CONSANGUINEOUS MARRIAGES AMONG A COHORT OF MULTIETHNIC HEALTH CARE PROVIDERS IN SAUDI ARABIA.

This study aimed to assess knowledge, attitude and practice related to consanguinity among multiethnic health care providers in the Kingdom of Saudi Arabia. Using a cross-sectional study design, a validated, self-administered close-ended questionnaire was randomly distributed to health care providers in different health institutions in the country between 1st August 2012 and 31st July 2013. A total of 1235 health care providers completed the study questionnaire. Of the 892 married participants (72.23% of total), 11.43% were married to a first cousin, and were predominantly Arabs, younger than 40 years and male. Only 17.80% of the patients seen by the health care providers requested consanguinity related counselling. A knowledge barrier was expressed by 27.49% of the participants, and 85.67% indicated their willingness to have more training in basic genetic counselling. A language barrier was expressed as a limiting factor to counselling for consanguinity among non-Arabs. The health care providers had a major dearth of knowledge that was reflected in their attitude and practice towards consanguinity counselling. This finding indicates the need for more undergraduate and postgraduate medical and nursing education and training in the counselling of consanguineous couples. It is recommended that consanguinity counselling is included in the current premarital screening and counselling programmes in the Kingdom.

Exome sequencing discloses KALRN homozygous variant as likely cause of intellectual disability and short stature in a consanguineous pedigree.

BACKGROUND: The recent availability of whole-exome sequencing has opened new possibilities for the evaluation of individuals with genetically undiagnosed intellectual disability. RESULTS: We report two affected siblings, offspring of first-cousin parents, with intellectual disability, hypotonia, short stature, growth hormone deficiency, and delayed bone age. All members of the nuclear family were genotyped, and exome sequencing was performed in one of the affected individuals. We used an in-house algorithm (CATCH v1.1) that combines homozygosity mapping with exome sequencing results and provides a list of candidate variants. One identified novel homozygous missense variant in KALRN (NM_003947.4:c.3644C>A: p.(Thr1215Lys)) was predicted to be pathogenic by all pathogenicity prediction software used (SIFT, PolyPhen, Mutation Taster). KALRN encodes the protein kalirin, which is a GTP-exchange factor protein with a reported role in cytoskeletal remodeling and dendritic spine formation in neurons. It is known that mice with ablation of Kalrn exhibit age-dependent functional deficits and behavioral phenotypes. CONCLUSION: Exome sequencing provided initial evidence linking KALRN to monogenic intellectual disability in man, and we propose that KALRN is the causative gene for the autosomal recessive phenotype in this family.

E-learning for research capacity strengthening in sexual and reproductive health: the experience of the Geneva Foundation for Medical Education and Research and the Department of Reproductive Health and Research, World Health Organization.

Technological advancement has resulted in the increasing use of e-learning and online education, initially in high-income countries and increasingly in low- and middle-income countries. BACKGROUND: In 2010, the Geneva Foundation for Medical Education and Research, in collaboration with the World Health Organization and partner institutions, developed an online postgraduate course "From Research to Practice: Training Course in Sexual and Reproductive Health Research". This course takes advantage of the advancing Internet technology to provide training opportunities to health professionals mostly from low- and middle-income countries whose access to quality education is constrained by time, financial resources, or both. CASE PRESENTATION: To assess the outcomes of the course, an evaluation was conducted by sending a self-administered questionnaire to graduates of the 2010-2012 programme. The objectives were to determine if the graduates had applied the knowledge gained from the course to their work and whether they had implemented their research project developed during the course. The evaluation also appraised the number of graduates who participated in the design or implementation of a new research project since the course concluded and whether the course had contributed to advancement in their careers. A total of 175 of 219 course graduates answered the questionnaire. The evaluation revealed that the majority of respondents (98%) had utilized the knowledge acquired, with nearly half of them (47%) having published a scientific paper as author or co-author. About a third of respondents (39%) had implemented their course research project and about three quarters of them (74%) have been involved in the design or implementation of a research project after completing the course. Over three quarters (81%) of respondents opined that the course had contributed to their career advancement and almost half of them (46%) had a career promotion as a direct or indirect benefit of the course. CONCLUSION: We surmise that the course positively impacted the participants' knowledge and understanding of sexual and reproductive health, which they applied in their professional work, as well as strengthened their research capacity. Success factors for the e-learning programme include tailor-made content to meet participants' needs, flexibility of access, and ongoing engagement/personal interactivity with course coaches.

Consanguinity and dysmorphology in Arabs.

Incidence rates of congenital disorders among the 350 million inhabitants of Arab countries could be influenced via the people's demographic and cultural characteristics. Arabs usually marry at a young age and have large families. They share certain core cultural values and beliefs, with the family accepted as the central structure of society. Consanguineous marriage is favored and respected in most if not all Arab communities, and intrafamilial unions currently account for 20-50% of all marriages. First-cousin unions are especially popular and constitute almost one quarter of all marriages in many Arab countries. Consequently, autosomal recessive (AR) dysmorphic syndromes constitute a considerable proportion of all birth defects among Arabs. Arab geneticists, with their persistent commitment to advancing research, have contributed to the description of a number of rare and new AR syndromes with the identification of novel genes. The collaboration with research teams in high-income countries resulted in a plethora of data on pathogenic variants and their function in causing dysmorphic syndromes. There could still be a considerable number of rare dysmorphic syndromes that prevail among Arabs which are not hitherto described and whose underlying molecular pathologies are not yet defined. Arab countries should thus strive to deploy DNA diagnostics and to build research capability around local priorities. Furthermore, a characterization of the prevailing genetic disorders in each geographic location, together with their mutations, is needed to plan for appropriate screening and testing protocols. An overview of consanguinity in Arab countries and examples of dysmorphology syndromes associated with consanguinity with their available molecular bases will be discussed.

A novel homozygous mutation in FGFR3 causes tall stature, severe lateral tibial deviation, scoliosis, hearing impairment, camptodactyly, and arachnodactyly.

Most reported mutations in the FGFR3 gene are dominant activating mutations that cause a variety of short-limbed bone dysplasias including achondroplasia and syndromic craniosynostosis. We report the phenotype and underlying molecular abnormality in two brothers, born to first cousin parents. The clinical picture is characterized by tall stature and severe skeletal abnormalities leading to inability to walk, with camptodactyly, arachnodactyly, and scoliosis. Whole exome sequencing revealed a homozygous novel missense mutation in the FGFR3 gene in exon 12 (NM_000142.4:c.1637C>A: p.(Thr546Lys)). The variant is found in the kinase domain of the protein and is predicted to be pathogenic. It is located near a known hotspot for hypochondroplasia. This is the first report of a homozygous loss-of-function mutation in FGFR3 in human that results in a skeletal overgrowth syndrome.

Diagnostic exome sequencing to elucidate the genetic basis of likely recessive disorders in consanguineous families.

Rare, atypical, and undiagnosed autosomal-recessive disorders frequently occur in the offspring of consanguineous couples. Current routine diagnostic genetic tests fail to establish a diagnosis in many cases. We employed exome sequencing to identify the underlying molecular defects in patients with unresolved but putatively autosomal-recessive disorders in consanguineous families and postulated that the pathogenic variants would reside within homozygous regions. Fifty consanguineous families participated in the study, with a wide spectrum of clinical phenotypes suggestive of autosomal-recessive inheritance, but with no definitive molecular diagnosis. DNA samples from the patient(s), unaffected sibling(s), and the parents were genotyped with a 720K SNP array. Exome sequencing and array CGH (comparative genomic hybridization) were then performed on one affected individual per family. High-confidence pathogenic variants were found in homozygosity in known disease-causing genes in 18 families (36%) (one by array CGH and 17 by exome sequencing), accounting for the clinical phenotype in whole or in part. In the remainder of the families, no causative variant in a known pathogenic gene was identified. Our study shows that exome sequencing, in addition to being a powerful diagnostic tool, promises to rapidly expand our knowledge of rare genetic Mendelian disorders and can be used to establish more detailed causative links between mutant genotypes and clinical phenotypes.

Recessive thrombocytopenia likely due to a homozygous pathogenic variant in the FYB gene: case report.

BACKGROUND: Inherited thrombocytopenias (IT) are a heterogeneous group of rare diseases characterized by a reduced number of blood platelets. The frequency of IT is probably underestimated because of diagnostic difficulties and because not all the existing forms have as yet been identified, with some patients remaining without a definitive diagnosis. Exome Sequencing has made possible the identification of almost all variants in the coding regions of protein-coding genes, thereby providing the opportunity to identify the disease causing gene in a number of patients with indefinite diagnoses, specifically in consanguineous families. CASE PRESENTATION: Familial thrombocytopenia with small size platelets was present in several members of a highly consanguineous family from Northern Iraq. Genotyping of all affected, their unaffected siblings and parents, followed by exome sequencing revealed a strong candidate loss of function variant in a homozygous state: a frameshift mutation in the FYB gene. The protein encoded by this gene is known to be a cytosolic adaptor molecule expressed by T, natural killer (NK), myeloid cells and platelets, and is involved in platelet activation and controls the expression of interleukin-2. Knock-out mice were reported to show isolated thrombocytopenia. CONCLUSION: Inherited thrombocytopenias differ in their presentation, associated features, and molecular etiologies. An accurate diagnosis is needed to provide appropriate management as well as counseling for the individuals and their family members. Exome sequencing may become a first diagnostic tool to identify the molecular basis of undiagnosed familial IT. In this report, the clinical evaluation combined with the power and efficiency of genomic analysis defined the FYB gene as the possible underlying cause of autosomal recessive thrombocytopenia with small platelet size. This is the first report linking pathogenic variants in FYB and thrombocytopenia in humans.

Microarray delineation of familial chromosomal imbalance with deletion 5q35 and duplication 10q25 in a child showing multiple anomalies and dysmorphism.

We describe a 6-month-old female with developmental delay, hypotonia, supernumerary nipples, and distinct craniofacial features. Postnatal chromosome analysis revealed an unbalanced karyotype involving a der (5) and array-CGH defined two unbalanced regions with partial 2.3 Mb deletion of 5q35.3 in combination with a large 19.5 Mb duplication of chromosome 10 from q25.3 to q26.3. Parental karyotyping analysis showed that the father was carrier of a balanced t(5;10)(q35;q25). Two cousins of the proband with similar facial features had the same unbalanced karyotype with presence of the der (5) inherited from the malsegregation of the familial translocation. Additionally, three siblings (two deceased and one abortion) manifested a more severe phenotype including congenital heart defect, cleft palate, and agenesis of the corpus callosum and were diagnosed with unbalanced karyotypes inherited from the familial balanced translocation.

Loss of CHSY1, a secreted FRINGE enzyme, causes syndromic brachydactyly in humans via increased NOTCH signaling.

We delineated a syndromic recessive preaxial brachydactyly with partial duplication of proximal phalanges to 16.8 Mb over 4 chromosomes. High-throughput sequencing of all 177 candidate genes detected a truncating frameshift mutation in the gene CHSY1 encoding a chondroitin synthase with a Fringe domain. CHSY1 was secreted from patients' fibroblasts and was required for synthesis of chondroitin sulfate moieties. Noticeably, its absence triggered massive production of JAG1 and subsequent NOTCH activation, which could only be reversed with a wild-type but not a Fringe catalytically dead CHSY1 construct. In vitro, depletion of CHSY1 by RNAi knockdown resulted in enhanced osteogenesis in fetal osteoblasts and remarkable upregulation of JAG2 in glioblastoma cells. In vivo, chsy1 knockdown in zebrafish embryos partially phenocopied the human disorder; it increased NOTCH output and impaired skeletal, pectoral-fin, and retinal development. We conclude that CHSY1 is a secreted FRINGE enzyme required for adjustment of NOTCH signaling throughout human and fish embryogenesis and particularly during limb patterning.

LRP4 mutations alter Wnt/beta-catenin signaling and cause limb and kidney malformations in Cenani-Lenz syndrome.

Cenani-Lenz syndrome (CLS) is an autosomal-recessive congenital disorder affecting distal limb development. It is characterized mainly by syndactyly and/or oligodactyly and is now shown to be commonly associated with kidney anomalies. We used a homozygosity-mapping approach to map the CLS1 locus to chromosome 11p11.2-q13.1. By sequencing candidate genes, we identified recessive LRP4 mutations in 12 families with CLS. LRP4 belongs to the low-density lipoprotein (LDL) receptor-related proteins (LRPs), which are essential for various developmental processes. LRP4 is known to antagonize LRP6-mediated activation of canonical Wnt signaling, a function that is lost by the identified mutations. Our findings increase the spectrum of congenital anomalies associated with abnormal lipoprotein receptor-dependent signaling.

Global developmental delay and intellectual disability in the era of genomics: Diagnosis and challenges in resource limited areas.

AIMS: To report the diagnostic yield of clinical singleton whole exome sequencing (WES) performed among a group of Jordanian children presenting with global developmental delay /intellectual disability (GDD/ID), discuss the underlying identified genetic disorders and the challenges encountered. PATIENTS AND METHODS: This retrospective medical record review study included 154 children who were diagnosed with GDD/ID at our clinic at Jordan University Hospital between 2016 and 2021, and whose diagnostic work up included WES. RESULTS: Consanguinity among parents was reported in 94/154 (61.0%) patients and history of other affected siblings in 35/154 (22.7%) patients. Pathogenic and likely pathogenic variants (solved cases) were reported in 69/154 (44.8%) patients, a variant of uncertain significance was reported in 54/154 (35.0%) and a negative result was reported in 31/154 (20.1%) cases. In the solved cases, autosomal recessive diseases were the most common (33/69; 47.8%). Metabolic disorders were identified in 20/69 (28.9%) patients, followed by developmental and epileptic encephalopathies (9/69; 13.0%) and MECP2 related disorders (7/69; 10.1%). Other single gene disorders were identified in 33/69; 47.8%) patients. CONCLUSION: This study had several limitations, as it was hospital-based and only including patients who were able to afford the test. Nevertheless, it yielded several important findings. In resource-limited countries, WES may be a reasonable approach. We discussed the challenges that clinicians meet in the context of shortage of resources.

Molecular characterization of glucose-6-phosphate dehydrogenase deficient variants in Baghdad city - Iraq.

BACKGROUND: Although G6PD deficiency is the most common genetically determined blood disorder among Iraqis, its molecular basis has only recently been studied among the Kurds in North Iraq, while studies focusing on Arabs in other parts of Iraq are still absent. METHODS: A total of 1810 apparently healthy adult male blood donors were randomly recruited from the national blood transfusion center in Baghdad. They were classified into G6PD deficient and non-deficient individuals based on the results of methemoglobin reduction test (MHRT), with confirmation of deficiency by subsequent enzyme assays. DNA from deficient individuals was studied using a polymerase chain reaction-Restriction fragment length polymorphism (PCR-RFLP) for four deficient molecular variants, namely G6PD Mediterranean (563 C→T), Chatham (1003 G→A), A- (202 G→A) and Aures (143 T→C). A subset of those with the Mediterranean variant, were further investigated for the 1311 (C→T) silent mutation. RESULTS: G6PD deficiency was detected in 109 of the 1810 screened male individuals (6.0%). Among 101 G6PD deficient males molecularly studied, the Mediterranean mutation was detected in 75 cases (74.3%), G6PD Chatham in 5 cases (5.0%), G6PD A- in two cases (2.0%), and G6PD Aures in none. The 1311 silent mutation was detected in 48 out of the 51 G6PD deficient males with the Mediterranean variant studied (94.1%). CONCLUSIONS: Three polymorphic variants namely: the Mediterranean, Chatham and A-, constituted more than 80% of G6PD deficient variants among males in Baghdad. Iraq. This observation is to some extent comparable to other Asian Arab countries, neighboring Turkey and Iran.

The changing profile of consanguinity rates in Bahrain, 1990-2009.

Consanguineous marriage is traditional and respected in most communities of North Africa, the Middle East and West Asia, including Bahrain, with intra-familial unions accounting for 20-50+% of all marriages. Significant secular changes in consanguinity rates have been reported in recent decades in different populations. Among parents of 14,237 newborns in Bahrain in 2008-2009, the total consanguinity and first cousin marriage rates over a period of four months in 2008 were 10.9% and 6.9% respectively, while during all of 2009 the rates were 11.4% and 6.8% respectively. The study confirms that over a ten-year period first cousin marriage rates in Bahrain have declined from 24% to nearly 7%. Although advice against cousin marriages was not attempted at any stage in the comprehensive community genetics programmes in Bahrain, increasing the literacy of the public and of the health care providers on prevention strategies for genetic diseases could have contributed to this decline in consanguinity rate in Bahrain.

Sickle cell disease in the Kurdish population of northern Iraq.

Epidemiological studies have revealed that sickle cell disease patients are clustered in two geographical areas in Iraq, one among the Arabs in the extreme south, another among the Kurdish population in the extreme north, where they constitute major health problems. However, no studies have focused on the genotypes responsible for sickle cell disease or the ß-globin gene haplotypes associated with it. For the latter purpose, a total of 103 unrelated Kurdish sickle cell disease patients were evaluated by restriction fragment length polymorphism (RFLP) for the sickle cell mutation, followed by multiplex polymerase chain reaction (PCR) and reverse hybridization for ß- and α-thalassemia (ß- and α-thal) mutations, whenever indicated. Results showed that the most common genotype was sickle cell anemia (68.0%) followed by Hb S/ß(0)-thal and Hb S/ß(+)-thal at frequencies of 24.2 and 7.8%, respectively. Eight ß-thal mutations were associated with the latter two genotypes including: IVS-II-1 (G>A), IVS-I-110 (G>A), codon 8 (-AA), codon 44 (-C), codon 22 (-7 bp), IVS-I-1 (G>A), codon 30 (G>C) and IVS-I-6 (T>C). In Hb SS patients, the -α(3.7) deletion was documented in 10.0% and was the only α-thal mutation detected. Furthermore, 5' ß-globin gene cluster haplotyping of 128 ß(S) chromosomes revealed that the most common haplotype seen in 69.5% was the Benin haplotype, followed by the Arab-Indian haplotype in 12.5%. These latter findings closely resemble reports from neighboring Turkey, Syria, Jordan, Lebanon and Mediterranean countries, suggesting a possible common origin, but are in contrast to findings from the Eastern Arabian Peninsula and Iran.

Generation of three human induced pluripotent stem cell lines with IRX5 knockout and knockin genetic editions using CRISPR-Cas9 system.

Studies on animal models have shown that Irx5 is an important regulator of cardiac development and that it regulates ventricular electrical repolarization gradient in the adult heart. Mutations in IRX5 have also been linked in humans to cardiac conduction defects. In order to fully characterize the role of IRX5 during cardiac development and in cardiomyocyte function, we generated three genetically-modified human induced pluripotent stem cell lines: two knockout lines (heterozygous and homozygous) and a knockin HA-tagged line (homozygous).