Fulminant Neonatal Liver Failure in MPV 17-Related Mitochondrial DNA Depletion Syndrome.

Mitochondrial depletion syndromes are well established causes of liver failure in infants. Hepatocerebral variant related to MPV17 gene defect is characterized by infantile onset of progressive liver failure, developmental delay, neurological manifestations, lactic acidosis, hypoglycemia, and mtDNA depletion in liver tissue. We report a hepatocerebral variant of mitochondrial DNA depletion syndrome in a neonate who presented with septic shock picture, hypoglycemia, jaundice, hypotonia, and rotatory nystagmus. Family history was significant for consanguinity and a brother who died at the age of 4 months. Investigations showed mild liver function derangement contrasting with severe coagulopathy, hyperlactatemia, and generalized aminoaciduria. The brain MRI was normal. Next generation sequencing (NGS) panel identified a MPV17 gene missense homozygous pathogenic variant. The infant expired at the age of 2 weeks with refractory ascites. This case illustrates a challenging diagnosis causing liver failure and death in neonatal period. Genetic testing of mitochondrial DNA depletion syndromes should be a part of liver failure workup in addition to other treatable disorders presenting with encephalo-hepatopathy in infancy.

Case report: Homozygous variants of NEB and KLHL40 in two Arab patients with nemaline myopathy.

Objective: Nemaline myopathies are a heterogeneous group of congenital myopathies caused by mutations in different genes associated with the structural and functional proteins of thin muscular filaments. Most patients have congenital onset characterized by hypotonia, respiratory issues, and abnormal deep tendon reflexes, which is a phenotype encountered in a wide spectrum of neuromuscular disorders. Whole-exome sequencing (WES) contributes to a faster diagnosis and facilitates genetic counseling. Methods: Here, we report on two Arab patients from consanguineous families diagnosed with nemaline myopathy of different phenotype spectrum severities. Results: Clinical assessment and particular prenatal history raised suspicion of neuromuscular disease. WES identified homozygous variants in NEB and KLHL40. Muscle biopsy and muscle magnetic resonance imaging studies linked the genetic testing results to the clinical phenotype. The novel variant in the NEB gene resulted in a classical type 2 nemaline myopathy, while the KLHL40 gene variant led to a severe phenotype of nemaline myopathy, type 8. Both patients were identified as having other gene variants with uncertain roles in their complex phenotypes. Conclusions: This study enriches the phenotypic spectrum of nemaline myopathy caused by NEB and KLHL40 variants and highlights the importance of detailed prenatal, neonatal, and infancy assessments of muscular weakness associated with complex systemic features. Variants of uncertain significance in genes associated with nemaline myopathy may be correlated with the phenotype. Early, multidisciplinary intervention can improve the outcome in patients with mild forms of nemaline myopathies. WES is essential for clarifying complex clinical phenotypes encountered in patients from consanguineous families. Targeted carrier screening of extended family members would enable accurate genetic counseling and potential genetic prevention.

Clinico-radiological features, molecular spectrum, and identification of prognostic factors in developmental and epileptic encephalopathy due to inosine triphosphate pyrophosphatase (ITPase) deficiency.

Developmental and epileptic encephalopathy 35 (DEE 35) is a severe neurological condition caused by biallelic variants in ITPA, encoding inosine triphosphate pyrophosphatase, an essential enzyme in purine metabolism. We delineate the genotypic and phenotypic spectrum of DEE 35, analyzing possible predictors for adverse clinical outcomes. We investigated a cohort of 28 new patients and reviewed previously described cases, providing a comprehensive characterization of 40 subjects. Exome sequencing was performed to identify underlying ITPA pathogenic variants. Brain MRI (magnetic resonance imaging) scans were systematically analyzed to delineate the neuroradiological spectrum. Survival curves according to the Kaplan-Meier method and log-rank test were used to investigate outcome predictors in different subgroups of patients. We identified 18 distinct ITPA pathogenic variants, including 14 novel variants, and two deletions. All subjects showed profound developmental delay, microcephaly, and refractory epilepsy followed by neurodevelopmental regression. Brain MRI revision revealed a recurrent pattern of delayed myelination and restricted diffusion of early myelinating structures. Congenital microcephaly and cardiac involvement were statistically significant novel clinical predictors of adverse outcomes. We refined the molecular, clinical, and neuroradiological characterization of ITPase deficiency, and identified new clinical predictors which may have a potentially important impact on diagnosis, counseling, and follow-up of affected individuals.

New Cohort of Patients With CEDNIK Syndrome Expands the Phenotypic and Genotypic Spectra.

OBJECTIVE: To report 6 new patients with cerebral dysgenesis, neuropathy, ichthyosis, and keratoderma (CEDNIK) syndrome. METHODS: Clinical exome or targeted sequencing were performed to elucidate the molecular genetic cause in patients with neurocognitive abnormalities and brain imaging findings. RESULTS: CEDNIK syndrome is a rare genetic condition caused by biallelic pathogenic loss-of-function variants in synaptosomal-associated protein 29 (SNAP29), which encodes a vesicular membrane fusion protein. Clinical manifestations include significant developmental delay/intellectual disability (DD/ID), brain abnormalities, failure to thrive, and skin abnormalities. To date, 19 patients from 10 unrelated families with CEDNIK syndrome have been reported. We report 5 additional patients with homozygous predicted loss-of-function variants in SNAP29 and one with compound heterozygous variants: a frameshift SNAP29 variant and a 370 kb deletion on 22q11.2. All patients exhibit DD/ID, ichthyosis and/or palmoplantar keratoderma, and hypotonia. Four of 6 subjects had hypomyelinated white matter on MRI, 2 of 6 had early puberty, and 4 of 6 had strabismus, which were previously rarely reported. Other phenotypes were variably present, including dysmorphic features, feeding difficulties, and recurrent respiratory infections. The cohort includes 2 siblings with a c.2T>C variant who have a relatively milder phenotype, a patient with the most C-terminal variant yet described (c.622G>T), and 3 patients with previously described variants (c.354dupG, c.487dupA). CONCLUSIONS: This cohort of 6 additional patients expands the genotypic and phenotypic spectrum of CEDNIK syndrome, highlighting previously under-recognized features such as hypomyelination, seizures, and early puberty. Owing to reduced penetrance of the skin phenotype, cerebral dysgenesis, and neuropathy, we propose renaming this syndrome SNAP29-related disorder.

A novel bi-allelic loss-of-function mutation in STIM1 expands the phenotype of STIM1-related diseases.

STIM1, the stromal interaction molecule 1, is the key protein for maintaining calcium concentration in the endoplasmic reticulum by triggering the Store Operated Calcium Entry (SOCE). Bi-allelic mutations in STIM1 gene are responsible for a loss-of-function in patients affected with a CRAC channelopathy syndrome in which severe combined immunodeficiency syndrome (SCID-like), autoimmunity, ectodermal dysplasia and muscle hypotonia are combined. Here, we studied two siblings from a consanguineous Syrian family, presenting with muscle weakness, hyperlaxity, elastic skin, tooth abnormalities, dysmorphic facies, hypoplastic patellae and history of respiratory infections. Using exome sequencing, we have identified a new homozygous frameshift mutation in STIM1: c.685delT [p.(Phe229Leufs*12)], leading to a complete loss of STIM1 protein. In this study, we describe an unusual phenotype linked to STIM1 mutations, combining clinical signs usually observed in different STIM1-related diseases. In particular, we confirmed that the complete loss of STIM1 function is not always associated with severe immune disorders. Altogether, our results broaden the spectrum of phenotypes associated with mutations in STIM1 and opens new perspectives on the pathological mechanisms associated with a defect in the proteins constituting the SOCE complex.

Bi-allelic GOT2 Mutations Cause a Treatable Malate-Aspartate Shuttle-Related Encephalopathy.

Early-infantile encephalopathies with epilepsy are devastating conditions mandating an accurate diagnosis to guide proper management. Whole-exome sequencing was used to investigate the disease etiology in four children from independent families with intellectual disability and epilepsy, revealing bi-allelic GOT2 mutations. In-depth metabolic studies in individual 1 showed low plasma serine, hypercitrullinemia, hyperlactatemia, and hyperammonemia. The epilepsy was serine and pyridoxine responsive. Functional consequences of observed mutations were tested by measuring enzyme activity and by cell and animal models. Zebrafish and mouse models were used to validate brain developmental and functional defects and to test therapeutic strategies. GOT2 encodes the mitochondrial glutamate oxaloacetate transaminase. GOT2 enzyme activity was deficient in fibroblasts with bi-allelic mutations. GOT2, a member of the malate-aspartate shuttle, plays an essential role in the intracellular NAD(H) redox balance. De novo serine biosynthesis was impaired in fibroblasts with GOT2 mutations and GOT2-knockout HEK293 cells. Correcting the highly oxidized cytosolic NAD-redox state by pyruvate supplementation restored serine biosynthesis in GOT2-deficient cells. Knockdown of got2a in zebrafish resulted in a brain developmental defect associated with seizure-like electroencephalography spikes, which could be rescued by supplying pyridoxine in embryo water. Both pyridoxine and serine synergistically rescued embryonic developmental defects in zebrafish got2a morphants. The two treated individuals reacted favorably to their treatment. Our data provide a mechanistic basis for the biochemical abnormalities in GOT2 deficiency that may also hold for other MAS defects.

Current management of Duchenne muscular dystrophy in the Middle East: expert report.

Aim: Duchenne muscular dystrophy (DMD) is a severe and rare X-linked neuromuscular childhood disorder that results in functional decline, loss of ambulation and early death due to cardiac or respiratory failure. The objective of this paper is to address different aspects of the current management of DMD in the Middle East, north Africa (MENA) region, and to gather experts' recommendations on how to optimally diagnose and treat patients suffering from this disease. Methods: A group of experts (neuromuscular medicine, neuropediatricians and geneticists) convened to discuss the diagnosis and management of DMD in the MENA region. A list of practical statements was prepared by the chair of the meeting to guide the discussions around critical aspects relating to the current and future management of DMD. Results & conclusion: Ideally, DMD management should be a multidisciplinary approach. Nevertheless, few tertiary care hospitals in the region are currently able to provide the full spectrum of medical expertise and services needed by DMD patients. Clinical practice in the region remains heterogeneous. Specific guidelines for diagnosis and treatment are needed in the MENA region to improve outcomes. Disease awareness among the general public and the medical community is lacking. Now that mutation-specific therapies are being developed and more widely studied, general education programs regarding early signs and symptoms, a standardized referral and diagnosis pathway, patient registries and support groups will significantly improve the management of the disease.

Decreased expression of circulating microRNA-126 in patients with type 2 diabetic nephropathy: A potential blood-based biomarker.

Circulating microRNAs (miRNAs) have been proposed as promising biomarkers for multiple diseases. miR-126 is reported to be associated with type 2 diabetes mellitus (T2D), diabetic nephropathy (DN) and end stage renal disease. The aim of this study was to investigate the expression of circulating miR-126 and to assess its potential as a blood-based biomarker for DN in T2D patients. In 52 patients with T2D without history of DN (with noromoalbuminuria), 50 patients with T2D and DN (29 with microalbuminuria and 21 with macroalbuminuria), and 50 non-diabetic healthy controls, the expression of circulating miR-126 in peripheral whole blood was evaluated by quantitative polymerase chain reaction. The expression levels of circulating miR-126 were significantly decreased in T2D patients and further decreased in DN patients compared with those in the controls. Multivariate logistic regression analysis confirmed the independent association of lower miR-126 levels with T2D [adjusted odds ratio (OR), 0.797; 95% confidence interval (CI), 0.613-0.960] and DN (adjusted OR, 0.513; 95% CI, 0.371-0.708). miR-126 levels were associated with the degree of albuminuria and showed significantly low expression in DN patients with microalbuminuria (adjusted OR, 0.781; 95% CI; 0.698-0.952) and further lower expression in DN patients with macroalbuminuria (adjusted OR, 0.433; 95% CI, 0.299-0.701), respectively compared with T2D patients with normoalbuminuria. miR-126 levels negatively correlated with albuminuria positively with glomerular filtration rate (P<0.05), and in addition, negatively correlated with fasting glucose, glycated hemoglobin, triglyceride and LDL (P<0.05). Stepwise multiple regression analysis identified albuminuria as a significant predictor of miR-126 (P<0.001). miR-126 in peripheral blood yielded area under the receiver operating characteristic curves of 0.854 (95% CI, 0.779-0.929) and 0.959 (95% CI, 0.916-1.000) in the differentiation of DN patients from T2D patients and DN patients from non-diabetic controls respectively. These data suggest that decreased expression of circulating miR-126 is associated with the development of DN in T2D patients, and may be a promising blood-based biomarker for DN risk estimation.

Exome Sequencing and the Management of Neurometabolic Disorders.

BACKGROUND: Whole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level. METHODS: To uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient's clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes. RESULTS: We performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 probands had been born to predominantly nonconsanguineous parents of European descent. In 37 probands, we identified variants in 2 genes newly implicated in disease, 9 candidate genes, 22 known genes with newly identified phenotypes, and 9 genes with expected phenotypes; in most of the genes, the variants were classified as either pathogenic or probably pathogenic. Complex phenotypes of patients in five families were explained by coexisting monogenic conditions. We obtained a diagnosis in 28 of 41 probands (68%) who were evaluated. A test of a targeted intervention was performed in 18 patients (44%). CONCLUSIONS: Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%. (Funded by BC Children's Hospital Foundation and others.).

Among a panel of polymorphisms in genes related to oxidative stress, CAT-262 C>T, GPX1 Pro198Leu and GSTP1 Ile105Val influence the risk of developing BCR-ABL negative myeloproliferative neoplasms.

OBJECTIVES: To analyze the relationship between six polymorphisms in genes related to oxidative stress, namely CAT-262 C>T, MnSOD Ala16Val, GPX1 Pro198Leu, GSTM1 and GSTT1 null genotypes, and GSTP1 Ile105Val, and the occurrence of BCR-ABL negative myeloproliferative neoplasms (polycythemia vera, essential thrombocythemia, and primary myelofibrosis). METHODS: We genotyped for these polymorphisms 328 patients with a known mutation status for JAK2 V617F, MPL and CALR, and 363 controls, using molecular genetics assays. RESULTS: The CAT-262 C>T and GPX1 Pro198Leu polymorphisms were seen significantly less frequently, while the GSTP1 IleVal105 polymorphism was seen significantly more frequently in patients with BCR-ABL negative myeloproliferative neoplasms, regardless of the molecular sub-type (e.g. JAK2 V617F or CALR mutated). DISCUSSION AND CONCLUSION: Our study provides evidence that variation in genes related to oxidative stress might modulate the risk of developing BCR-ABL negative myeloproliferative neoplasms.

Time-course effect of high-glucose-induced reactive oxygen species on mitochondrial biogenesis and function in human renal mesangial cells.

The present study investigated the time-course effect of high-glucose-induced reactive oxygen species (ROS) on mitochondrial biogenesis and function in human renal mesangial cells and the effect of direct inhibition of ROS on mitochondria. The cells were cultured for 1, 4, and 7 days in normal glucose or high glucose in the presence and absence of Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP) or catalase. Mitochondrial ROS production was assessed by confocal microscope. mtDNA copy number and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), nuclear respiratory factors 1 (NRF-1), and mitochondrial transcription factor A (TFAM) transcripts were analyzed by real-time PCR. PGC-1α, NRF-1, and TFAM proteins were analyzed by Western blotting. Mitochondrial function was determined by assessing mitochondrial membrane potential and adenosine triphosphate (ATP) levels. High glucose induced significant increases in mitochondrial superoxide and hydrogen peroxide (H2 O2 ) at day 1, which remained significantly elevated at days 4 and 7. The copy number of mtDNA and expression of PGC-1α, NRF-1, and TFAM were significantly increased at 1 day in high glucose but were significantly decreased at 4 and 7 days. A progressive decrease in mitochondrial membrane potential was observed at 1, 4, and 7 days in high glucose, and this was associated with decreased ATP levels. Treatment of cells with MnTBAP or catalase during high-glucose incubation attenuated ROS production and reversed the alterations in mitochondrial biogenesis and function. Increased mitochondrial biogenesis in human renal mesangial cells may be an early adaptive response to high-glucose-induced ROS, and prolonged ROS production induced by chronic high glucose decreased mitochondrial biogenesis and impaired mitochondrial function. Protection of mitochondria from high-glucose-induced ROS may provide a potential approach to retard the development and progression of diabetic nephropathy.

[Use of MLPA test in the detection of subtelomeric rearrangements--case report]. / Utilitatea testului MLPA in depistarea rearanjamentelor subtelomerice--discutii pe marginea unor cazuri de retard mintal idiopatic.

Genetic causes of mental retardation (MR) are heterogeneous, but subtelomeric rearrangements are an important one. MLPA technique provides the best results in case detection. We have used MLPA to identify subtelomeric rearrangements in children with idiopatic MR. The protocol included: clinical selection; karyotype; antiFMRP test; MLPA. We have selected cases using de Vries diagnostic score. Patient data were recorded in a database. The group was formed of 142 MR children. In 24 (16.9%) the karyotype was abnormal. 16 cases (11.3%) presented speech delay/autism, but antiFMRP test was normal. 60 MLPA tests were done: 46 cases (76.7% were normal, 6 (10%) abnormal, 4 (6.7%) had polymorphism and 4 (6.7%) could not be interpreted. Clinical features of the cases identified are illustrated. In conclusion, the diagnostic score is useful in case selection for further testing and MLPA proves to be efficient in diagnosing subtelomeric rearrangements as a possible cause of idiopatic MR.

[MLPA technique--principles and use in practice]. / Tehnica MLPA. Principii si utilitate practica.

MLPA (Multiplex Ligation-dependent Probe Amplification) is a recently introduced method, based on PCR principle, useful for the detection of different genetic abnormalities (aneuploidies, gene deletions/duplications, subtelomeric rearrangements, methylation status etc). The technique is simple, reliable and cheap. We present this method to discuss its importance for a modern genetic service and to underline its multiple advantages.

Failure to detect DUP25 in lymphoblastoid cells derived from patients with panic disorder and control individuals representing European and American populations.

Investigation of the co-occurrence of panic and phobic disorders with joint laxity led to the identification of interstitial duplications involving human chromosome 15q24-26 (named 'DUP25') in a Spanish population. DUP25 was observed in 97% of patients and in 7% of control individuals. In the present study, we used two different methods to detect DUP25: high-throughput molecular gene dosage analysis and fluorescence in situ hybridization (FISH). We evaluated 56 lymphoblastoid cell lines derived from 26 unrelated patients with panic disorder obtained from several European and American populations and 30 normal controls. We could not find any cell line showing a result consistent with DUP25. These data do not support any association of DUP25 with panic disorder.

Retinoblastoma, pinealoma, and mild overgrowth in a boy with a deletion of RB1 and neighbor genes on chromosome 13q14.

We report on a 10-year-old boy with a normal karyotype and a chromosome 13q14 deletion of the retinoblastoma gene (RB1) by fluorescence in situ hybridization (FISH). He showed subtle signs of overgrowth, including macrocephaly, hepatomegaly, and inguinal hernia. The boy also had cryptorchism and mild developmental delay. In his first months of life, variant Wiedemann-Beckwith syndrome was tentatively suspected and he was included in a careful tumor prevention program. At the age of 11 months, bifocal retinoblastoma of the left eye was diagnosed. Pinealoma was suspected at the age of 19 months and was removed by neurosurgery at the age of 29 months. At 4 years and 4 months, the deletion of the RB1 gene was suspected on clinical grounds and was diagnosed by FISH and molecular studies. At that time, he was a near-normal healthy playful kindergarten child, height 107 cm (-0.3 SD), OFC 52.5 cm (+0.8 SD), developmental age 3-3.5 years. The combination of retinoblastoma, pinealoma, and deletion of the RB1 gene diagnosed by FISH has not been reported previously. The deletion spans at least 370-420 kb in size and is predicted to include proximal and distal neighbor genes. This report may assist in establishing the clinical signs of the contiguous gene syndrome at the RB1 locus on 13q14.

Molecular cytogenetic characterization of a 10p14 deletion that includes the DGS2 region in a patient with multiple anomalies.

We report on a prenatally diagnosed four-month-old boy with DiGeorge-like phenotype and a deletion of chromosome 10pter --> 14. Fluorescence in situ hybridization (FISH) experiments using phage artificial chromosome (PAC) and yeast artificial chromosome (YAC) clones indicated that the chromosomal breakpoint was located at the proximal boundary of the DiGeorge syndrome 2 (DGS2) critical region. The patient demonstrated a high forehead, high arched eyebrows, short palpebral fissures, sparse eyelashes, prominent nose with bulbous tip, small mouth, receding chin, round ears with deficient helices, cardiac defects atrial septal defect (ASD), ventricular septal defect (VSD), mild brachytelephalangy, mild syndactyly, hypoplastic left kidney, undescended testes, muscular hypertonia, dorsally flexed big toes, and developmental delay. The phenotype corresponded well with the clinical signs of 10p deletion of this region that were described previously. The facial features appeared different from the typical face with the 22q11 deletion.