Search

The ionotropic glutamate delta receptor GluD1, encoded by the GRID1 gene, is involved in synapse formation, function, and plasticity. GluD1 does not bind glutamate, but instead cerebellin and D-serine, which allow the formation of trans-synaptic bridges, and trigger transmembrane signaling. Despite wide expression in the nervous system, pathogenic GRID1 variants have not been characterized in humans so far. We report homozygous missense GRID1 variants in five individuals from two unrelated consanguineous families presenting with intellectual disability and spastic paraplegia, without (p.Thr752Met) or with (p.Arg161His) diagnosis of glaucoma, a threefold phenotypic association whose genetic bases had not been elucidated previously. Molecular modeling indicated that Arg161His and Thr752Met mutations alter the hinge between GluD1 cerebellin and D-serine binding domains and the stiffness of this latter domain, respectively. Expression, trafficking, physical interaction with metabotropic glutamate receptor mGlu1, and cerebellin binding of GluD1 mutants were not conspicuously altered. Conversely, we found that both GluD1 mutants hampered signaling of metabotropic glutamate receptor mGlu1/5 via the ERK pathway in neurons of primary cortical culture. Moreover, both mutants impaired dendrite morphology and excitatory synapse density in neurons of primary hippocampal culture. These results show that the clinical phenotypes are distinct entities segregating in the families as an autosomal recessive trait, and caused by pathophysiological effects of GluD1 mutants involving metabotropic glutamate receptor signaling and neuronal connectivity. Our findings unravel the importance of the GluD1 receptor signaling in sensory, cognitive and motor functions of the human nervous system.

Aldosterone synthase deficiency (ASD) is a rare potentially life-threatening genetic disorder that usually presents during infancy due to pathogenic variants in the CYP11B2 gene. Knowledge about CYP11B2 variants in the Arab population is scarce. Here, we present and analyze five Palestinian patients and their different novel pathogenic variants. Data on clinical presentation, electrolytes, plasma renin activity, and steroid hormone levels of five patients diagnosed with ASD were summarized. Sequencing of the CYP11B2 gene exons was followed by evolutionary conservation analysis and structural modeling of the variants. All patients were from highly consanguineous Palestinian families. The patients presented at 1-4 months of age with recurrent vomiting, poor weight gain, hyponatremia, hyperkalemia, and low aldosterone levels. Genetic analysis of the CYP11B2 gene revealed three homozygous pathogenic variants: p.Ser344Profs*9, p.G452W in two patients from an extended family, and p.Q338stop. A previously described pathogenic variant was found in one patient: p.G288S. We described four different CYP11B2 gene pathogenic variants in a relatively small population. Our findings may contribute to the future early diagnosis and therapy for patients with ASD among Arab patients who present with failure to thrive and compatible electrolyte disturbances.

Calpainopathies constitute a heterogeneous group of disorders resulting from deficiencies in calpains, calcium-specific proteases that modulate substrates by limited proteolysis. Clinical manifestations depend on tissue-specific expression of the defective calpain and substrate specificity. CAPN15, encoding the Drosophila small optic lobes (sol) homolog, was recently found to cause various eye defects in individuals carrying bi-allelic missense variants. Here we report on two siblings with manifestations reminiscent of Johanson-Blizzard syndrome including failure to thrive, microcephaly, global developmental delay, dysmorphic features, endocrine abnormalities and congenital malformations, in addition to eye abnormalities. Exome sequencing identified a homozygous 47 base-pair deletion in a minimal intron of CAPN15, including the splice donor site. Sequencing of cDNA revealed single exon skipping, resulting in an out-of-frame deletion with a predicted premature termination codon. These findings expand the phenotypic spectrum associated with CAPN15 variants, and suggest that complete loss-of-function is associated with a recognizable syndrome of congenital malformations and developmental delay, overlapping Johanson-Blizzard syndrome and the recently observed brain defects in Capn15 knockout (KO) mice. Moreover, the data highlight the unique opportunity for indel detection in minimal introns.

We report a loss-of-function mutation in the TLDc domain of human Oxidation Resistance 1 (OXR1) gene, resulting in early-onset epilepsy, developmental delay, cognitive disabilities, and cerebellar atrophy. Patient lymphoblasts show impaired cell survival, proliferation, and hypersensitivity to oxidative stress. These phenotypes are rescued by TLDc domain replacement. We generated patient derived induced pluripotent stem cells (iPSCs) revealing impaired neural differentiation along with dysregulation of genes essential for neurodevelopment. We identified that OXR1 influences histone arginine methylation by activating protein arginine methyltransferases (PRMTs), suggesting OXR1 dependent mechanisms regulating gene expression during neurodevelopment. We modeled the function of OXR1 in early human brain development using patient derived brain organoids revealing that OXR1 contributes to the spatial-temporal regulation of histone arginine methylation in specific brain regions. Our work provides new insights into pathological features and molecular underpinnings associated with OXR1 deficiency, highlighting the therapeutic potential of OXR1 in numerous neurodegenerative and neurodevelopmental disorders.

Cytochrome c oxidase (COX), a multimeric protein complex, is the final electron acceptor in the mitochondrial electron transfer chain. Primary COX deficiency, caused by mutations in either mitochondrial DNA or nuclear-encoded genes, is a heterogenous group of mitochondrial diseases with a wide range of presentations, ranging from fatal infantile to subtler. We previously reported a patient with primary COX deficiency due to a pathogenic variant in COX4I1 (encoding the common isoform of COX subunit 4, COX4-1), who presented with bone marrow failure, genomic instability, and short stature, mimicking Fanconi anemia (FA). In the present study, we demonstrated that accumulative DNA damage coincided primarily with proliferative cells in the patient’s fibroblasts and in COX4i1 knockdown cells. Expression analysis implicated a reduction in DNA damage response pathways, which was verified by demonstrating impaired recovery from genotoxic insult and decreased DNA repair. The premature senescence of the COX4-1-deficient cells prevented us from undertaking additional studies; nevertheless, taken together, our results indicate replicative stress and impaired nuclear DNA damage response in COX4-1 deficiency. Interestingly, our in vitro findings recapitulated the patient’s presentation and present status.

Cytochrome- c- oxidase (COX), a multimeric protein complex, is the final electron acceptor in the mitochondrial electron transfer chain. Primary COX deficiency, caused by mutations in either mitochondrial DNA or nuclear-encoded genes, is a heterogenous group of mitochondrial diseases with a wide range of presentations ranging from fatal infantile to subtler. We previously reported a patient with primary COX deficiency due to a pathogenic variant in COX4I1 (encoding the common isoform of COX subunit 4), who presented with bone-marrow failure, genomic instability and short stature, mimicking Fanconi anemia (FA). In the present study, we demonstrated reduced proliferation and premature senescence in this patient’s fibroblasts and in COX4-1 knockdown cells. Accumulative DNA damage coincided primarily with proliferative cells, indicating replicative stress. Expression analysis implicated DNA damage response which was verified by demonstrating impaired recovery from genotoxic insult and decreased DNA repair. Interestingly, our in-vitro findings recapitulate the patient’s presentation and present status. Thus, we suggest that the premature senescence, resulting from accumulative DNA damage in COX4-1 deficiency is a protective mechanism to avoid malignant transformation in a similar manner to what was reported for FA and other “accelerated aging diseases”.

Regulation of neuronal connectivity and synaptic communication are key to proper functioning of the brain. The Netrin-G subfamily and their cognate receptors are vertebrate-specific synaptic cell adhesion molecules with a role in synapse establishment and function, which seem to have co-evolved to contribute to higher brain functions. We identified a homozygous frameshift variant in NTNG2 (NM_032536.3: c.376dup), encoding Netrin-G2, in eight individuals from four families with global developmental delay, hypotonia, secondary microcephaly, and autistic features. Comparison of haplotypes established this as a founder variant. Previous studies showed that Ntng2-knockout mice have impaired visual, auditory, and motor coordination abilities required for demanding tasks, as well as possible spatial learning and memory deficits. Knockout of Ntng2 in a cellular model resulted in short neurites, and knockout of its trans-synaptic partner Ngl2/Lrrc4 in mice revealed autistic-like behavior and reduced NMDAR synaptic plasticity. The Ngl2/Lrrc4-knockout mouse phenotype was rescued by NMDAR activation, suggesting a mechanistic link to autism spectrum disorder. We thus propose NTNG2 as a candidate disease gene and provide further support for the involvement of Netrin-G2 in neuropsychiatric phenotypes.

Avoidance of fasting and regular ingestion of uncooked-cornstarch have long been the mainstay dietary treatment of Glycogen Storage Disease type Ia (GSD-Ia). However, GSD-Ia patients who despite optimal dietary treatment show poor glycemic control and are intolerant to cornstarch, present a complex clinical challenge. We pursued Whole Exome Sequencing (WES) in three such unrelated patients, to both confirm a molecular diagnosis of GSD-Ia, and seek additional variants in other genes (e.g. genes associated with amylase production) which may explain their persistent symptoms. WES confirmed the GSD-Ia diagnosis, with all three probands harboring the homozygous p.R83C variant in G6PC. While no other significant variants were identified for patients A and B, a homozygous p.G276V variant in the SI gene was detected in patient C, establishing the dual-diagnosis of GSD-Ia and Sucrase-Isomaltase Deficiency. To conclude, we suggest that WES should be considered in GSD-Ia patients who show persistent symptoms despite optimal dietary management.

RBL2/p130 is one of three highly conserved members of the retinoblastoma (RB) protein family. It is strongly upregulated during neuronal differentiation and brain development, and is critical for survival of post-mitotic neurons. Similar to RB1, it has been implicated as a tumor suppressor gene and has been shown to be dysregulated in various types of cancer. Recent publications describe biallelic, germline loss of function variants in RBL2 in individuals with profound developmental delay. We report a child with profound developmental delay, microcephaly, and hypotonia, who developed fulminant exophthalmos at age 6 years. Brain MRI followed by a biopsy of an intra-orbital mass revealed a mesenchymal tumor. Post-surgical histopathologic examination of the resected tumor was compatible with diagnosis of nodular fasciitis. Exome sequencing from peripheral blood identified a biallelic frameshift variant (c.901dupT) in RBL2. Notably, no malignancies were reported in previous cases with RBL2 variants. This case provides a possible association between RBL2 and orbital tumors.

Despite being the first homolog of the bacterial RecQ helicase to be identified in humans, the function of RECQL1 remains poorly characterized. Furthermore, unlike other members of the human RECQ family of helicases, mutations in RECQL1 have not been associated with a genetic disease. Here, we identify 2 families with a genome instability disorder that we have named RECON (RECql ONe) syndrome, caused by biallelic mutations in the RECQL gene. The affected individuals had short stature, progeroid facial features, a hypoplastic nose, xeroderma, and skin photosensitivity and were homozygous for the same missense mutation in RECQL1 (p.Ala459Ser), located within its zinc binding domain. Biochemical analysis of the mutant RECQL1 protein revealed that the p.A459S missense mutation compromised its ATPase, helicase, and fork restoration activity, while its capacity to promote single-strand DNA annealing was largely unaffected. At the cellular level, this mutation in RECQL1 gave rise to a defect in the ability to repair DNA damage induced by exposure to topoisomerase poisons and a failure of DNA replication to progress efficiently in the presence of abortive topoisomerase lesions. Taken together, RECQL1 is the fourth member of the RecQ family of helicases to be associated with a human genome instability disorder.

Rab proteins coordinate inter-organellar vesicle-mediated transport, facilitating intracellular communication, protein recycling, and signaling processes. Dysfunction of Rab proteins or their direct interactors leads to a wide range of diseases with diverse manifestations. We describe seven individuals from four consanguineous Arab Muslim families with an infantile-lethal syndrome, including failure to thrive (FTT), chronic diarrhea, neonatal respiratory distress, variable pituitary dysfunction, and distal arthrogryposis. Exome sequencing analysis in the independent families, followed by an internal gene-matching process using a local exome database, identified a homozygous splice-site variant in MADD (c.2816 + 1 G > A) on a common haplotype. The variant segregated with the disease in all available family members. Determination of cDNA sequence verified single exon skipping, resulting in an out-of-frame deletion. MADD encodes a Rab guanine nucleotide exchange factor (GEF), which activates RAB3 and RAB27A/27B and is thus a crucial regulator of neuromuscular junctions and endocrine secretory granule release. Moreover, MADD protects cells from caspase-mediated TNF-α-induced apoptosis. The combined roles of MADD and its downstream effectors correlate with the phenotypic spectrum of disease, and call for additional studies to confirm the pathogenic mechanism and to investigate possible therapeutic avenues through modulation of TNF-α signaling.

We describe a novel autosomal recessive form of mitochondrial disease in a child with short stature, poor weight gain, and mild dysmorphic features with highly suspected Fanconi anemia due to a mutation in COX4I1 gene. Whole Exome Sequencing was performed then followed by Sanger confirmation, identified a K101N mutation in COX4I1, segregating with the disease. This nuclear gene encodes the common isoform of cytochrome c oxidase (COX) subunit 4 (COX 4-1), an integral regulatory part of COX (respiratory chain complex IV) the terminal electron acceptor of the mitochondrial respiratory chain. The patient’s fibroblasts disclosed decreased COX activity, impaired ATP production, elevated ROS production, decreased expression of COX4I1 mRNA and undetectable (COX4) protein. COX activity and ATP production were restored by lentiviral transfection with the wild-type gene. Our results demonstrate the first human mutation in the COX4I1 gene linked to diseases and confirm its role in the pathogenesis. Thus COX4I1 mutations should be considered in any patient with features suggestive of this diagnosis.

Hypomyelinating leukodystrophies are a group of neurodevelopmental disorders that affect proper formation of the myelin sheath in the central nervous system. They are characterized by developmental delay, hypotonia, spasticity, and variable intellectual disability. We used whole exome analysis to study the molecular basis of hypomyelinating leukodystrophy in two sibs from a consanguineous family. A homozygous mutation, c.3068+5G>A, was identified in the ATRN gene, with the consequent insertion of an intronic sequence into the patients' cDNA and a predicted premature termination of the ATRN polypeptide. ATRN encodes Attractin, which was previously shown to play a critical role in central myelination. Several spontaneous ATRN rodent mutants exhibited impaired myelination which was attributed to oxidative stress and accelerated apoptosis. ATRN can now be added to the growing list of genes associated with hypomyelinating leukodystrophy. The disease seems to be confined to the CNS; however, given the young age of our patients, longer follow-up may be required.

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare autosomal recessive renal disorder characterized by excessive renal magnesium and calcium loss, bilateral nephrocalcinosis, and progressive renal failure, due to impaired tubular reabsorption in the thick ascending loop of Henle. FHHNC is caused by loss of function mutations in the claudin-16 gene (CLDN16) and claudin-19 gene (CLDN19). A 2-month-old male infant presented with convulsions during hypomagnesemia, hypocalcemia, and hypophosphatemia, biochemical findings were consistent with FHHNC. There is a positive family history of the death of a 12 years old sibling due to renal failure. Gene sequencing of the CLDN16 revealed a novel missense mutation with the replacement of T by C in codon 120 located in exon 2, predicting cysteine to arginine substitution p.Cys120Arg. This is the first description of this missense mutation and the first confirmation of FHHNC by molecular testing in a Palestinian family which enables genetic counseling and future prenatal diagnosis.

Mitochondrial encephalopathies are a heterogeneous group of disorders that, usually carry grave prognosis. Recently a homozygous mutation, Gly372Ser, in the TIMM50 gene, was reported in an abstract form, in three sibs who suffered from intractable epilepsy and developmental delay accompanied by 3-methylglutaconic aciduria. We now report on four patients from two unrelated families who presented with severe intellectual disability and seizure disorder, accompanied by slightly elevated lactate level, 3-methylglutaconic aciduria and variable deficiency of mitochondrial complex V. Using exome analysis we identified two homozygous missense mutations, Arg217Trp and Thr252Met, in the TIMM50 gene. The TIMM50 protein is a subunit of TIM23 complex, the mitochondrial import machinery. It serves as the major receptor in the intermembrane space, binding to proteins which cross the mitochondrial inner membrane on their way to the matrix. The mutations, which affected evolutionary conserved residues and segregated with the disease in the families, were neither present in large cohorts of control exome analyses nor in our ethnic specific exome cohort. Given the phenotypic similarity, we conclude that missense mutations in TIMM50 are likely manifesting by severe intellectual disability and epilepsy accompanied by 3-methylglutaconic aciduria and variable mitochondrial complex V deficiency. 3-methylglutaconic aciduria is emerging as an important biomarker for mitochondrial dysfunction, in particular for mitochondrial membrane defects.

Background Of our 1400 exome-studied patients, 67% originate from consanguineous families. ∼80% suffer from variable degree of intellectual disability (ID). The search for disease causing genes using homozygosity mapping was progressing slowly until 2010, then markedly accelerated by the introduction of exome analysis. Objectives To identify the disease causing mutation(s) in three patients from two unrelated families who suffered from global developmental delay, severe ID and drug-responsive seizure disorder. Methods Exome analysis was performed in DNA of the three patients. The identified PIGC variants were generated and transfected into PIGC-defective mouse cells and the restoration of the surface expression of mouse CD90, CD48 and FLAER was assessed using flow cytometry. The expression of these proteins was also studied on the surface of patients9 leucocytes. Results Three PIGC mutations were identified; homozygous p.L189W in one family and compound heterozygosity for p.L212P/p.R21X variants in another. PIGC participates in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor which tethers proteins to plasma membrane. In cells lacking PIGC protein, which were transfected with each of the PIGC variants, we detected a clear reduction of surface expression of GPI-anchored proteins. Furthermore, analyses of patients9 leucocytes showed significant and constant decrease of CD16 surface expression in granulocytes, and moderate decrease of CD14, CD55, CD59 and FLAER levels. Conclusions PIGC joins the list of genes in which mutations result in defective biosynthesis of GPI anchoring, manifesting by global developmental delay and seizure disorder. The lack of specific biomarker dictates exome sequencing as the diagnostic procedure of choice in similar patients.

DNA repair mechanisms such as nucleotide excision repair (NER) and translesion synthesis (TLS) are dependent on proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory protein. Recently, homozygosity for p.Ser228Ile mutation in the PCNA gene was reported in patients with neurodegeneration and impaired NER. Using exome sequencing, we identified a homozygous deleterious mutation, c.648delAG, in the PARP10 gene, in a patient suffering from severe developmental delay. In agreement, PARP10 protein was absent from the patient cells. We have previously shown that PARP10 is recruited by PCNA to DNA damage sites and is required for DNA damage resistance. The patient cells were significantly more sensitive to hydroxyurea and UV-induced DNA damage than control cells, resulting in increased apoptosis, indicating DNA repair impairment in the patient cells. PARP10 deficiency joins the long list of DNA repair defects associated with neurodegenerative disorders, including ataxia telangiectasia, xeroderma pigmentosum, Cockayne syndrome, and the recently reported PCNA mutation.

Congenital toxoplasmosis represents the second most commonly recognized congenital infection. Ocular and neurological abnormalities are considered the most frequent sequelae. Endocrinological manifestations are rare and have received little attention. We report a 3.5-month-old female infant who presented with failure to thrive and recurrent hypoglycemic attacks, diagnosed as growth hormone deficiency due to sequelae of congenital toxoplasmosis. Although endocrinological sequelae of congenital toxoplasmosis are uncommon, they represent potentially treatable conditions. Here, we stress on the importance of monitoring pituitary function and growth in children in particular, with congenital toxoplasmosis, keeping in mind other possible, potentially treatable, endocrinological manifestations.

Here, we describe a single patient from a consanguineous family, who suffers from developmental delay, intellectual disability, hypermetropia, moderate alternating esotropia, unsteady gait, and peripheral polyneuropathy. Brain MRI revealed basal ganglia disease. Exome analysis disclosed a homozygous variant, c.452G>C (p.(Arg151Thr)), in TID1, encoding a mitochondrial J-protein chaperone that is known for its function in assisting the Hsp70 chaperone, mortalin, in mediating the refolding of denatured protein and dissolving protein aggregates. Results from in vitro import assays showed that both wild type and c.452G>C (p.(Arg151Thr)) are efficiently imported into isolated mitochondria. However, the import rate of the c.452G>C (p.(Arg151Thr)) variant was less than that of the wild-type protein. In the second part of this study, we demonstrated, in vitro, that the disaggregation function of the mortalin/Tid1 team is compromised in the TID1 c.452G>C (p.(Arg151Thr)) variant, as its chaperone activity has a level similar to that of the non-functional H→Q HPD domain variant. The results shed light on the essential function played by Tid1 during neuronal development.

ObjectiveTo identify the genetic basis of a childhood-onset syndrome of variable severity characterised by progressive spinocerebellar ataxia, mental retardation, psychotic episodes and cerebellar atrophy.MethodsIdentification of the underlying mutations by whole exome and whole genome sequencing. Consequences were examined in patients’ cells and in yeast.ResultsTwo brothers from a consanguineous Palestinian family presented with progressive spinocerebellar ataxia, mental retardation and psychotic episodes. Serial brain imaging showed severe progressive cerebellar atrophy. Whole exome sequencing revealed a novel mutation: pitrilysin metallopeptidase 1 (PITRM1) c.2795C>T, p.T931M, homozygous in the affected children and resulting in 95% reduction in PITRM1 protein. Whole genome sequencing revealed a chromosome X structural rearrangement that also segregated with the disease. Independently, two siblings from a second Palestinian family presented with similar, somewhat milder symptoms and the same PITRM1 mutation on a shared haplotype. PITRM1T931M carrier frequency was 0.027 (3/110) in the village of the first family evaluated, and 0/300 among Palestinians from other locales. PITRM1 is a mitochondrial matrix enzyme that degrades 10–65 amino acid oligopeptides, including the mitochondrial fraction of amyloid-beta peptide. Analysis of peptide cleavage activity by the PITRM1T931M protein revealed a significant decrease in the degradation capacity specifically of peptides ≥40 amino acids.ConclusionPITRM1T931M results in childhood-onset recessive cerebellar pathology. Severity of PITRM1-related disease may be affected by the degree of impairment in cleavage of mitochondrial long peptides. Disruption and deletion of X linked regulatory segments may also contribute to severity.

Background L-serine plays an essential role in neuronal development and function. Although a non-essential amino acid, L-serine must be synthesised within the brain because of its poor permeability by the blood–brain barrier. Within the brain, its synthesis is confined to astrocytes, and its shuttle to neuronal cells is performed by a dedicated neutral amino acid transporter, ASCT1. Methods and results Using exome analysis we identified the recessive mutations, p.E256K, p.L315fs, and p.R457W, in SLC1A4 , the gene encoding ASCT1, in patients with developmental delay, microcephaly and hypomyelination; seizure disorder was variably present. When expressed in a heterologous system, the mutations did not affect the protein level at the plasma membrane but abolished or markedly reduced L-serine transport for p.R457W and p.E256K mutations, respectively. Interestingly, p.E256K mutation displayed a lower L-serine and alanine affinity but the same substrate selectivity as wild-type ASCT1. Conclusions The clinical phenotype of ASCT1 deficiency is reminiscent of defects in L-serine biosynthesis. The data underscore that ASCT1 is essential in brain serine transport. The SLC1A4 p.E256K mutation has a carrier frequency of 0.7% in the Ashkenazi-Jewish population and should be added to the carrier screening panel in this community.

Nephrogenic diabetes insipidus (NDI) is a urinary concentrating defect resulting from resistance of the collecting duct to the antidiuretic action of vasopressin (AVP). The X-linked recessive form is the most frequent genetic cause of inherited NDI and can be caused by mutations in the gene encoding the V2 vasopressin receptor (AVPR2). A Palestinian male infant presented in the neonatal period with failure to thrive, vomiting, irritability, fever, and polyuria, and had biochemical findings consistent with NDI. The diagnosis of NDI was established based on the clinical picture, absent response to desmopressin, and a similarly affected elder brother. Sequencing of the AVPR2 gene for the patient and his affected brother revealed a novel missense mutation with replacement of G by A in codon 82 located in exon 2 (TGC → TAC), causing a cysteine to tyrosine substitution (C82Y). Testing of the mother showed that she was the carrier of that mutation. This is the identified AVPR2 mutation in a Palestinian family. Knowledge of these mutations will allow genetic counseling and early diagnosis of affected males.

Objective We report an infant with panhypopituitarism presenting with cholestatic jaundice, hypoglycemia, and high ferritin level. Methods We conducted clinical and laboratory investigations, including metabolic, infectious, and hormonal evaluation. Results Hormonal evaluation revealed panhypopituitarism (cortisol deficiency, growth hormone deficiency, and central hypothyroidism). Other causes of cholestasis were ruled out. Surprisingly, serum ferritin level was very high suggesting neonatal hemochromatosis, which was ruled out by the absence of hemosiderin deposition in buccal mucosal biopsy. Replacement therapy with glucocorticoids and L-thyroxin showed improvement of liver function tests, resolved cholestatic jaundice, and significantly decreased serum ferritin level. These findings support the assumption that thyroid hormone and cortisol affect the bile acid-independent bile flow. Conclusion This is the first description of an infant with congenital panhypopituitarism, presenting with cholestasis, hypoglycemia, and high serum ferritin level. Panhypopituitarism should be considered in any infant who presents with cholestasis, hypoglycemia, and other manifestations of pituitary malfunction. High serum ferritin level probably reflects acute phase reaction.

Primary bile acid malabsorption (PBAM) is associated with congenital diarrhea, steatorrhea, and a block in the intestinal return of bile acids in the enterohepatic circulation. Mutations in the ileal Na+-dependent bile acid transporter (ASBT; SLC10A2) can cause PBAM, but do not appear to account for most familial cases. Another major transporter involved in the intestinal reclamation of bile acids is the heteromeric Organic Solute Transporter alpha-beta (OSTα-OSTβ; SLC51A-SLC51B), which exports bile acid across the basolateral membrane. Here we report the first patients with OSTβ deficiency, clinically characterized by chronic diarrhea, severe fat soluble vitamin deficiency, and features of cholestatic liver disease including elevated serum gamma-glutamyltransferase activity. Whole exome sequencing revealed a homozygous single nucleotide deletion in codon 27 of SLC51B, resulting in a frameshift and premature termination at codon 50. Functional studies in transfected cells showed that the SLC51B mutation resulted in markedly reduced taurocholic acid uptake activity and reduced expression of the OSTα partner protein. Conclusion: The findings identify OSTβ deficiency as a new cause of congenital chronic diarrhea with features of cholestatic liver disease. These studies underscore OSTα-OSTβ's key role in the enterohepatic circulation of bile acids in humans. This article is protected by copyright. All rights reserved.

In response to Ravera et al. "Fanconi anemia: from DNA repair to metabolism" commenting on our recent publication by Abu-Libdeh, Douiev et al., describing a pathogenic variant in the COX 4I1 gene simulating Fanconi anemia, we wish to add supplementary, pertinent information linking cytochrome c oxidase (COX, mitochondrial respiratory chain complex IV) dysfunction to oxidative stress and nuclear DNA damage. Elevated production of reactive oxygen species (ROS) in COX 4I1 deficient fibroblasts was detected in cells grown in glucose free medium and normalized by ascorbate or N-acetylcysteine supplementation. A pilot study shows positive nuclear staining with antibodies against Phospho-Histone H2A.X (Ser 139) indicating double-stranded DNA breaks (DBSs) both in COX 4I1 and in COX6B1 deficient fibroblasts. Additional investigation is required, and ongoing, to elucidate the precise mechanism of DNA damage in mitochondrial respiratory chain dysfunction and how it could be prevented.

Ubiquitination is a posttranslational modification that regulates many cellular processes including protein degradation, intracellular trafficking, cell signaling, and protein-protein interactions. Deubiquitinating enzymes (DUBs), which reverse the process of ubiquitination, are important regulators of the ubiquitin system. OTUD6B encodes a member of the ovarian tumor domain(OTU)-containing subfamily of deubiquitinating enzymes. Herein, we report biallelic pathogenic variants in OTUD6B in 12 individuals from 6 independent families with an intellectual disability syndrome associated with seizures and dysmorphic features. In subjects with predicted loss-of-function alleles, additional features include global developmental delay, microcephaly, absent speech, hypotonia, growth retardation with prenatal onset, feeding difficulties, structural brain abnormalities, congenital malformations including congenital heart disease, and musculoskeletal features. Homozygous Otud6b knockout mice were subviable, smaller in size, and had congenital heart defects, consistent with the severity of loss-of-function variants in humans. Analysis of peripheral blood mononuclear cells from an affected subject showed reduced incorporation of 19S subunits into 26S proteasomes, decreased chymotrypsin-like activity, and accumulation of ubiquitin-protein conjugates. Our findings suggest a role for OTUD6B in proteasome function, establish that defective OTUD6B function underlies a multisystemic human disorder, and provide additional evidence for the emerging relationship between the ubiquitin system and human disease.

This study describes the course of an OXA-48-producing Enterobacteriaceae (OPE) outbreak that started in March 2012 in a neonatal intensive care unit (NICU) in Jerusalem, Israel. During the peak of the outbreak (January to August 2012), there were 49 patients who had proven or suspected acquisition of OPE in the NICU, including 16 with invasive infections, out of a total of 156 patients who were hospitalized during that period. Three children hospitalized in the pediatric ICU were identified as carriers of OPE. Three patients with a previous stay in the affected NICU were identified as OPE carriers upon admission to another hospital. The Ministry of Health was notified and then intervened in July 2012. Intervention included cohorting colonized patients, conducting frequent rectal-culture surveillance, and improving the implementation of infection control practices. As a result, the incidence of OPE acquisition declined to 5 cases in the first 4 months, followed by no new cases in the next 3 months. Thirty-one patient-unique isolates were available for analysis: 29 Klebsiella pneumoniae isolates, all belonging to a single clone (sequence type 39 [ST39]), and 2 isolates from Enterobacter cloacae . All isolates possessed the bla OXA-48 and bla CTX-M-14 genes, which are located on the same plasmid. This plasmid, similar to the global bla OXA-48 -harboring vector, has now acquired bla CTX-M-14 , leading to resistance to all β-lactam agents.

Introduction Glycine encephalopathy (GE), also known as non-ketotic hyperglycinemia (NKH), is a rare inborn error of glycine metabolism caused by a defect in glycine cleavage system, a multi-enzyme complex located in mitochondrial membrane. This defect results in elevated glycine concentration in plasma and cerebrospinal fluid (CSF). Clinical manifestations vary from severe lethargy, hypoactivity and apneic episodes in the neonatal form, mild or moderate psychomotor delay and seizures in the infantile form, and abnormal behaviors, ataxia and choreoathetoid movements in late onset form. More than 50 GLDC mutations were found, reflecting large heterogeneity of the gene. Methods We describe the clinical, biochemical and molecular characteristics of three Palestinian siblings who have distinct clinical phenotypes. Molecular study was performed utilizing standard Polymerase Chain Reaction (PCR) amplification then direct DNA sequencing for the affected family members. Results Their phenotypes included severe symptoms in neonatal period, infantile onset of seizure and psychomotor delay and a mild late-onset form with speech delay at age 20 months. All siblings were homozygous for a novel mutation Y164H in exon 4 of GLDC gene. The described novel homozygous variant in our study is predicted deleterious and pathogenic. Conclusions This article further expands the genetic spectrum of glycine encephalopathy and adds an evidence of the clinical heterogeneity of glycine encephalopathy even in siblings with identical mutation.

Mutation in a growing spectrum of genes is known to either cause or contribute to primary or secondary microcephaly. In primary microcephaly the genetic determinants frequently involve mutations that contribute to or modulate the microtubule cytoskeleton by causing perturbations of neuronal proliferation and migration. Here we describe four patients from two unrelated families each with an infantile neurodegenerative disorder characterized by loss of developmental milestones at 9–24 months of age followed by seizures, dystonia and acquired microcephaly. The patients harboured homozygous missense mutations (A475T and A586V) in TBCD, a gene encoding one of five tubulin-specific chaperones (termed TBCA-E) that function in concert as a nanomachine required for the de novo assembly of the α/β tubulin heterodimer. The latter is the subunit from which microtubule polymers are assembled. We found a reduced intracellular abundance of TBCD in patient fibroblasts to about 10% (in the case of A475T) or 40% (in the case of A586V) compared to age-matched wild type controls. Functional analyses of the mutant proteins revealed a partially compromised ability to participate in the heterodimer assembly pathway. We show via in utero shRNA-mediated suppression that a balanced supply of tbcd is critical for cortical cell proliferation and radial migration in the developing mouse brain. We conclude that TBCD is a novel functional contributor to the mammalian cerebral cortex development, and that the pathological mechanism resulting from the mutations we describe is likely to involve compromised interactions with one or more TBCD-interacting effectors that influence the dynamics and behaviour of the neuronal cytoskeleton.

Desbuquois dysplasia (DD) is characterized by antenatal and postnatal short stature, multiple dislocations, and advanced carpal ossification. Two forms have been distinguished on the basis of the presence (type 1) or the absence (type 2) of characteristic hand anomalies. We have identified mutations in calcium activated nucleotidase 1 gene (CANT1) in DD type 1. Recently, CANT1 mutations have been reported in the Kim variant of DD, characterized by short metacarpals and elongated phalanges. DD has overlapping features with spondyloepiphyseal dysplasia with congenital joint dislocations (SDCD) due to Carbohydrate (chondroitin 6) Sulfotransferase 3 (CHST3) mutations. We screened CANT1 and CHST3 in 38 DD cases (6 type 1 patients, 1 Kim variant, and 31 type 2 patients) and found CANT1 mutations in all DD type 1 cases, the Kim variant and in one atypical DD type 2 expanding the clinical spectrum of hand anomalies observed with CANT1 mutations. We also identified in one DD type 2 case CHST3 mutation supporting the phenotype overlap with SDCD. To further define function of CANT1, we studied proteoglycan synthesis in CANT1 mutated patient fibroblasts, and found significant reduced GAG synthesis in presence of beta-D-xyloside, suggesting that CANT1 plays a role in proteoglycan metabolism. Hum Mutat 33:1261-1266, 2012. (c) 2012 Wiley Periodicals, Inc.

Ethylmalonic encephalopathy (EE) is a rare autosomal recessive disorder caused by mutations in the ETHE1 gene and characterized by chronic diarrhea, encephalopathy, relapsing petechiae and acrocyanosis. Nephrotic syndrome has been described in an infant with EE but the renal histology findings were not described in previous reports. We report a Palestinian girl with EE who presented with chronic diarrhea, encephalopathy, petechial rash and acrocyanosis. Subsequently, she developed progressive deterioration of renal function caused by rapidly progressive glomerulonephritis resulting in death within few days. This is, to our knowledge, the first reported occurrence of rapidly progressive glomerulonephritis in a child with ethylmalonic encephalopathy. Its presence is a serious complication associated with poor prognosis and may be explained by the diffuse vascular damage.

Propionic acidemia manifesting with hyperglycemia is rare. Few cases have been reported mainly of the neonatal-onset form associated with high mortality. We report a 9-month-old Palestinian boy who manifested with coma, severe hyperglycemia and ketoacidosis mimicking diabetic ketoacidosis. Family history of unexplained infant deaths was helpful in reaching the correct diagnosis. In response to therapy, the patient regained consciousness without neurologic deficits and had normal examination. This is, to our knowledge, the first case report of late-onset propionic acidemia that had this presentation and survived.

The composition of the neuronal cell surface dictates synaptic plasticity and thereby cognitive development. This remodeling of the synapses is governed by the endocytic network which internalize transmembrane proteins, then sort them back to the cell surface or carry them to the lysosome for degradation. The multi-protein retromer complex is central to this selection, capturing specific transmembrane proteins and remodeling the cell membrane to form isolated cargo-enriched transport carriers. We investigated a consanguineous family with four patients who presented in infancy with intractable myoclonic epilepsy and lack of psychomotor development. Using exome analysis, we identified a homozygous deleterious mutation in SNX27, which encodes sorting nexin 27, a retromer cargo adaptor. In western analysis of patient fibroblasts, the encoded mutant protein was expressed at an undetectable level when compared with a control sample. The patients' presentation and clinical course recapitulate that reported for the SNX27 knock-out mouse. Since the cargo proteins for SNX27-mediated sorting include subunits of ionotropic glutamate receptors and endosome-to-cell surface synaptic insertion of AMPA receptors is severely perturbed in SNX27(-/-) neurons, it is proposed that at least part of the neurological aberrations observed in the patients is attributed to defective sorting of ionotropic glutamate receptors. SNX27 deficiency is now added to the growing list of neurodegenerative disorders associated with retromer dysfunction.

Mucolipidosis II (ML II) and Mucolipidosis type III (ML III) are autosomal recessive disorders of lysosomal hydrolases trafficking due to the deficiency of the multimeric enzyme, UDP- N -acetylglucosamine-1-phosphotransferase. The α/β subunits encoded by the GNPTA gene is the catalytic subunit of the enzyme while the gamma recognition subunit is encoded by the GNPTAG gene. We report the molecular analysis of GNPTA in 21 families with ML II and 3 families with ML III. The ML II mutant genotypes included three splice-site mutations [IVS1-2A > G; IVS17 + 1G > A; IVS18 + 1G > A] in seven Palestinian, Israeli Arab-Muslims, and Turkish patients; a two base pair deletion [c.3502_3delCT] in 11 patients from Israel, Turkey, and Ireland; two nonsense mutations [c.2533C > T (Q845X); c.3613C > T (R1205X)], in a Turkish and an Arab-Muslim patient from the Nablus area, respectively, and an insertion mutation [c.2916insT] in a patient from Nablus. The ML III mutant genotypes included a splice-site mutation [IVS17 + 6T > G] in two patients from Irish/Scottish origin who were compound heterozygous for a nonsense mutation [c.3565C > T (R1189X)] and the deletion mutation [c.3502_3delCT], respectively. The third ML III patient from France was compound heterozygous for a missense mutation [c.1196C > T] and the same deletion [c.3502_3delCT] found homozygous in 11 ML II patients. The 21 ML II patients were homozygous while the three ML III patients were compound heterozygous for mutations in GNPTA. The results of this study confirm that ML II or ML III phenotype is not due to the localization of the mutations, but rather to the severity of the mutations, ML II and ML III might be allelic, and ML III is genetically heterogeneous. We suggest that the diseases due to mutations in GNPTA represent a clinical continuum between ML III and ML II, and the classification of these diseases should be based on the age of onset, clinical symptoms, and severity.

We studied three newly diagnosed xeroderma pigmentosum complementation group G patients with markedly different clinical features. An Israeli-Palestinian girl (XP96TA) had severe abnormalities suggestive of the xeroderma pigmentosum/Cockayne syndrome complex including sun sensitivity, neurologic and developmental impairment, and death by age 6 y. A Caucasian girl (XP82DC) also had severe sun sensitivity with neurologic and developmental impairment and died at 5.8 y. In contrast, a mildly affected 14-y-old Caucasian female (XP65BE) had sun sensitivity but no neurologic abnormalities. XP96TA, XP82DC, and XP65BE fibroblasts showed marked reductions in post-ultraviolet cell survival and DNA repair but these were higher in XP65BE than in XP82DC. XP96TA fibroblasts had very low XPG mRNA expression levels whereas XP65BE fibroblasts had nearly normal levels. Host cell reactivation of an ultraviolet-treated reporter assigned all three fibroblast strains to the rare xeroderma pigmentosum complementation group G (only 10 other patients previously reported). XP96TA and XP82DC cells had mutations in both XPG alleles that are predicted to result in severely truncated proteins including stop codons and two base frameshifts. The mild XP65BE patient had an early stop codon mutation in the paternal allele. The XP65BE maternal allele had a single base missense mutation (G2817A, Ala874Thr) that showed residual ability to complement xeroderma pigmentosum complementation group G cells. These observations agree with earlier studies demonstrating that XPG mutations, which are predicted to lead to severely truncated proteins in both alleles, were associated with severe xeroderma pigmentosum/Cockayne syndrome neurologic symptoms. Retaining residual functional activity in one allele was associated with mild clinical features without neurologic abnormalities.

Background Celiac disease (CD) is a complex autoimmune disorder that can lead to an inflammatory small intestinal villous atrophy and malabsorption. Hartnup disease is an autosomal recessive disorder caused by increased urinary excretion of neutral amino acids. Co-occurrence of Hartnup disease and CD is extremely rare with only a single case reported. Case presentation We report a 3-year girl with chronic diarrhea, Hypoalbuminemia and exfoliative erythema. She was diagnosed with celiac disease, which did not improve on gluten free diet. Hartnup disease was suspected and was confirmed by neutral aminoaciduria. Niacin was started and followed by dramatic improvement. Conclusion Presence of Celiac and Hartnup disease in single individual is very rare. Complete nutritional assessment of refractory celiac patient can reveal underlying nutritional deficiency.

We report on a female infant with congenital iron storage disease, facial dysmorphism, intractable diarrhea, and hair abnormalities. The intractable diarrhea failed to resolve despite total parenteral nutrition and complete bowel rest for more than 3 weeks. The patient also had elevated liver enzymes and failure to thrive. Histopathologic examination of the liver revealed marked iron deposits in hepatocytes with portal edema, fibrosis, and septal formation. No metabolic abnormalities could be detected. She died at the age of 10 months. We suggest that this case could have a specific iron storage syndrome that is similar to the two sibs reported by Stankler et al. [1982; Arch Dis Child 57:212-216] and Verloes et al. [1997; Am J Med Genet 68:391-395]. The condition was called the tricho-hepato-enteric (THE) syndrome.

DNA repair mechanisms such as Nucleotide Excision Repair (NER) and Translesion Synthesis (TLS) are dependent on proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory protein. Recently, homozygosity for p.Ser228Ile mutation in the PCNA gene was reported in patients with neurodegeneration and impaired NER. Using exome sequencing we identified a homozygous deleterious mutation, c.648delAG, in the PARP10 gene, in a patient suffering from infantile neurodegeneration. In agreement, PARP10 protein was absent from the patient cells. We have previously shown that PARP10 is recruited by PCNA to DNA damage sites and is required for DNA damage resistance. The patient cells were significantly more sensitive to hydroxyurea and UV-induced DNA damage than control cells, resulting in increased apoptosis, indicating DNA repair impairment in the patient cells. PARP10 deficiency joins the long list of DNA repair defects associated with neurodegenerative disorders, including ataxia telangiectasia, xeroderma pigmentosum, Cockayne syndrome and the recently reported PCNA mutation.

A 7-month old girl with GM1 gangliosidosis type 1 manifested with diffuse ecchymosis and Mongolian spots. The cutaneous lesions were present at birth before the appearance of the other features of the disease. We postulate that dermal pigmentation may be recognized as an early sign of GM1 gangliosidosis.

The land of Palestine is among the most storied and fought-over parts of the world. Having drawn together in city-states, one of which was Jericho, the Canaanites were the earliest known inhabitants of Palestine, with roots there extending as far back as the third millennium bc. Located at the intersection of routes connecting three continents, Asia, Africa, and Europe, Palestine became a natural meeting place, as well as a battleground, for culture and religious influences from Syria, Mesopotamia, Egypt, and Asia Minor. Although the Hebrews, Semitic tribes from Mesopotamia, began to steadily immigrate into Palestine after the fourteenth century bc, it was not until around 1125 bc, more than 150 years after Moses led his people out of serfdom in Egypt, that they finally defeated the Canaanites. A more formidable opponent to the Hebrews proved to be the Philistines, who had established an independent state on the southern coast of Palestine and controlled the Canaanite town of Jerusalem. Owing to their military superiority, they soundly defeated the Israelites around 1050 bc. The Union of the Israelite tribes under King David, however, enabled the Hebrews to defeat the Philistines approximately 50 years later and assimilate with the Canaanites. After David’s death in 922 bc, the kingdom was divided into two sections, Israel, which fell to Assyria in 722 bc, and Judah, which fell to Babylonia in 586; as a result, Jerusalem was destroyed and most of the Jews were exiled. Not long afterward, however, Cyrus the Great of Persia conquered Babylonia and allowed the Jews to return, permitting them significant autonomy in the process.

Hyperornithinemia, hyperammonemia, and homocitrullinuria (HHH) syndrome is caused by mutations in the SLC25A15 (ORNT1) gene encoding the mitochondrial ornithine transporter, but the mechanism of pathogenesis of the encephalopathy, spastic paraparesis and hepatopathy remains undetermined. HHH syndrome was diagnosed in a 2-year-old Palestinian boy with developmental delay and seizures, and subsequently in his 13-year-old brother with developmental delay. Direct sequencing of the PCR products of SLC25A15 exon amplifications revealed that both brothers were homozygous for a novel 446G deletion in exon 3 as well as for a 760A>T (I254L) polymorphism in exon 5, which is downstream of a premature termination codon produced by the frameshift resulting from the 446G deletion. The index patient had elevated liver enzymes as well as hyperalaninemia, lactic acidemia with an elevated lactate to pyruvate ratio, and increased urinary excretion of lactate, glutarate and Krebs cycle intermediates. These findings are indicative of mitochondrial dysfunction and are in accordance with ultrastructural studies showing increased numbers of large and bizarre mitochondria in liver, muscle, leukocytes and fibroblasts of some HHH patients. Neurologic and hepatic manifestations are characteristic of some primary mitochondrial disorders. Secondary mitochondrial dysfunction may contribute to the pathogenesis of these same features in HHH syndrome.

Congenital afibrinogenemia is a rare autosomal recessive disorder characterized by the complete absence of detectable fibrinogen. We previously identified the first causative mutations for this disease, homozygous deletions of approximately 11 kb of the fibrinogen alpha chain gene (FGA). Subsequent analyses revealed that most afibrinogenemia alleles are truncating mutations of FGA, although mutations in all 3 fibrinogen genes, FGG, FGA andFGB have been identified. In this study, we performed the first prenatal diagnosis for afibrinogenemia. The causative mutation in a Palestinian family was a novel nonsense mutation in theFGB gene, Trp467Stop (W467X). Expression of the Trp467Stop mutant FGB cDNA in combination with wild-typeFGA and FGG cDNAs showed that fibrinogen molecules containing the mutant beta chain are not secreted into the media. The fetus was found to be heterozygous for the Trp467Stop mutation by direct sequencing and by linkage analysis, a result that was confirmed in the newborn by intermediate fibrinogen levels.

In 1975 Say et al. (Humangenetik 26:267-269) reported on a new dominantly inherited syndrome of cleft palate, short stature, microcephaly, large ears, and hand anomalies in 4 members of a family. This is a report of a 13-month-old girl with cleft palate, short stature, microcephaly, sparse scalp hair, large abnormally shaped ears, small hands with tapering fingers, delayed bone age, unusual dermatoglyphics, proximal renal tubular acidosis with cystic dysplasia of the kidneys, and developmental delay. This case appears to be the second report of this syndrome which presumably occurred as a new mutation in this family.