Muddathir H. Hamad

Loss-of-Function Mutations in FRRS1L Lead to an Epileptic-Dyskinetic Encephalopathy

Glutamatergic neurotransmission governs excitatory signaling in the mammalian brain, and abnormalities of glutamate signaling have been shown to contribute to both epilepsy and hyperkinetic movement disorders. The etiology of many severe childhood movement disorders and epilepsies remains uncharacterized. We describe a neurological disorder with epilepsy and prominent choreoathetosis caused by biallelic pathogenic variants in FRRS1L, which encodes an AMPA receptor outer-core protein. Loss of FRRS1L function attenuates AMPA-mediated currents, implicating chronic abnormalities of glutamatergic neurotransmission in this monogenic neurological disease of childhood.

Management of convulsive status epilepticus in children: an adapted clinical practice guideline for pediatricians in Saudi Arabia

Objective: To increase the use of evidence-based approaches in the diagnosis, investigations and treatment of Convulsive Status Epilepticus (CSE) in children in relevant care settings. Method: A Clinical Practice Guideline (CPG) adaptation group was formulated at a university hospital in Riyadh. The group utilized 2 CPG validated tools including the ADAPTE method and the AGREE II instrument. Results: The group adapted 3 main categories of recommendations from one Source CPG. The recommendations cover; (i)first-line treatment of CSE in the community; (ii)treatment of CSE in the hospital; and (iii)refractory CSE. Implementation tools were built to enhance knowledge translation of these recommendations including a clinical algorithm, audit criteria, and a computerized provider order entry. Conclusion: A clinical practice guideline for the Saudi healthcare context was formulated using a guideline adaptation process to support relevant clinicians managing CSE in children.

Mutation in GM2A Leads to a Progressive Chorea-dementia Syndrome.

Background The etiology of many cases of childhood-onset chorea remains undetermined, although advances in genomics are revealing both new disease-associated genes and variant phenotypes associated with known genes. Methods We report a Saudi family with a neurodegenerative course dominated by progressive chorea and dementia in whom we performed homozygosity mapping and whole exome sequencing. Results We identified a homozygous missense mutation in GM2A within a prominent block of homozygosity. This mutation is predicted to impair protein function. Discussion Although discovered more than two decades ago, to date, only five patients with this rare form of GM2 gangliosidosis have been reported. The phenotype of previously described GM2A patients has been typified by onset in infancy, profound hypotonia and impaired volitional movement, intractable seizures, hyperacusis, and a macular cherry red spot. Our findings expand the phenotypic spectrum of GM2A mutation-positive gangliosidosis to include generalized chorea without macular findings or hyperacusis and highlight how mutations in neurodegenerative disease genes may present in unexpected ways.

Auto-immune anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis: three case reports

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a recently identified auto-immune disorder characterised by severe memory deficit, a decreased level of consciousness, seizures, autonomic dysfunction and movement disorders. Three girls with the disorder are reported; they were aged 4 years, 5 years and 10 months. The 10-month-old infant who is one of the youngest patients reported with anti-NMDAR encephalitis worldwide, had MRI features suggestive of herpes simplex encephalitis (known to trigger anti-NMDAR encephalitis), but CSF PCR for herpes simplex was negative. All the patients presented with seizures, behavioural change, regression of speech, dystonia and choreo-athetosis. Anti-NMDAR antibodies were detected in all patients’ sera and cerebrospinal fluid (CSF). Intravenous immunoglobulin, corticosteroids and rituximab were administered at different intervals. Cases 1 and 2 made a full recovery, but case 3 has mild motor and speech delay. Patients who present with encephalopathy, seizures and movement disorders should be tested for anti-NMDAR antibodies in serum and CSF in addition to being screened for herpes simplex encephalitis.

Glutaric aciduria type 1 as a cause of dystonic cerebral palsy

Glutaric aciduria type 1 (GA1) is an inherited inborn error of metabolism caused by a deficiency of the enzyme glutaryl Co-A dehydrogenase (GCDH). Here, we report a 14-month-old Saudi boy with GA1 who presented with severe dystonia and was mis-diagnosed as cerebral palsy (CP). He presented to our institute with encephalopathy following an episode of gastroenteritis. His physical examination showed dystonia and spastic quadriplegia. His investigations revealed elevated both urinary 3-hydroxy glutaric acid, and serum glutarylcarnitine. The DNA analysis confirmed homozygosity for a mutation in the GCDH-coding gene (c.482G>A;p.R161Q). This case alerts pediatricians to consider GA1 as a differential diagnosis of children presenting with dystonic CP.

Mutations in the AMPA receptor complex protein FRRS1L cause an inherited Huntington-like chorea-dementia syndrome

OBJECTIVES: To unravel the cause of a novel Huntington-like phenotype in humans. BACKGROUND: Although most patients with progressive chorea and dementia harbor CAG expansions in Huntington disease (HTT), a proportion of patients are HTT-negative. DESIGN/METHODS: In a multiplex, consanguineous Saudi family with four siblings with juvenile onset chorea, dementia and seizures with normal HTT alleles, we applied a combined homozygosity mapping and exome sequencing approach to identify novel genes. RESULTS: Our studies uncovered a homozygous premature truncation mutation in FRRS1L, an AMPA receptor complex constituent, that segregated with affected status within the family. We detected an additional unrelated patient with biallelic mutations and a similar phenotype. Validation studies revealed markedly decreased protein abundance and evidence of protein mislocalization, consistent with loss of the membrane-interacting domain. CONCLUSIONS: These results indicate that mutations in FRRS1L cause a novel Huntington-like phenotype in humans and implicate AMPA receptor dysfunction in hereditary chorea, dementia and seizures. Disclosure: Dr. Salih has nothing to disclose. Dr. Madeo has nothing to disclose. Dr. Fields has nothing to disclose. Dr. Jepperson has nothing to disclose. Dr. Seidahmed has nothing to disclose. Dr. El Khashab has nothing to disclose. Dr. Hamad has nothing to disclose. Dr. Kruer has nothing to disclose.

Impact of PYROXD1 deficiency on cellular respiration and correlations with genetic analyses of limb-girdle muscular dystrophy in Saudi Arabia and Sudan

Next generation sequencing is commonly used to screen for pathogenic mutations in families with Mendelian disorders, but due to the pace of discoveries, gaps have widened for some diseases between genetic and pathophysiological knowledge. We recruited and analyzed 16 families with limb-girdle muscular dystrophy (LGMD) of Arab descent from Saudi Arabia and Sudan who did not have confirmed genetic diagnoses. The analysis included both traditional and next generation sequencing approaches. Cellular and metabolic studies were performed on Pyroxd1 siRNA C2C12 myoblasts and controls. Pathogenic mutations were identified in 8 of the 16 families. One Sudanese family of Arab descent residing in Saudi Arabia harbored a homozygous c.464A>G, p.Asn155Ser mutation in PYROXD1, a gene recently reported in association with myofibrillar myopathy and whose protein product reduces thiol residues. Pyroxd1 deficiency in murine C2C12 myoblasts yielded evidence for impairments of cellular proliferation, migration, and differentiation. Similar results were obtained with overexpression of p.Asn155Ser mutant human PYROXD1 in C2C12 myoblasts. Knockdown of CG10721 (Pyroxd1 fly homologue) in Drosophila yielded a lethal phenotype. Further investigations indicated that Pyroxd1 does not localize to mitochondria, yet Pyroxd1 deficiency is associated with decreased cellular respiration. This study identified pathogenic mutations in half of the LGMD families from the cohort, including one in PYROXD1. Developmental impairments were demonstrated in vitro for Pyroxd1 deficiency and in vivo for CG10721 deficiency, with reduced metabolic activity in vitro for Pyroxd1 deficiency.Next-generation sequencing is commonly used to screen for pathogenic mutations in families with Mendelian disorders, but due to the pace of discoveries, gaps have widened for some diseases between genetic and pathophysiological knowledge. We recruited and analyzed 16 families with limb-girdle muscular dystrophy (LGMD) of Arab descent from Saudi Arabia and Sudan who did not have confirmed genetic diagnoses. The analysis included both traditional and next-generation sequencing approaches. Cellular and metabolic studies were performed on Pyroxd1 siRNA C2C12 myoblasts and controls. Pathogenic mutations were identified in eight of the 16 families. One Sudanese family of Arab descent residing in Saudi Arabia harbored a homozygous c.464A>G, p.Asn155Ser mutation in PYROXD1, a gene recently reported in association with myofibrillar myopathy and whose protein product reduces thiol residues. Pyroxd1 deficiency in murine C2C12 myoblasts yielded evidence for impairments of cellular proliferation, migration, and differentiation, while CG10721 (Pyroxd1 fly homolog) knockdown in Drosophila yielded a lethal phenotype. Further investigations indicated that Pyroxd1 does not localize to mitochondria, yet Pyroxd1 deficiency is associated with decreased cellular respiration. This study identified pathogenic mutations in half of the LGMD families from the cohort, including one in PYROXD1. Developmental impairments were demonstrated in vitro for Pyroxd1 deficiency and in vivo for CG10721 deficiency, with reduced metabolic activity in vitro for Pyroxd1 deficiency.

Assessment of physicians’ knowledge and attitudes in the management of febrile seizures

OBJECTIVE To assess the knowledge and attitudes of physicians in different specialties who are involved in the care of children with FS. METHODS We assessed knowledge and attitudes in the management of Febrile seizure (FS) among physicians working in different specialties in the Kingdom of Saudi Arabia using a questionnaire-based cross-sectional study conducted from September-December 2016. RESULTS Of the 300 physicians who responded to the questionnaire, 178 (59.3%) were males, 119 (39.7%) were consultants, 92 (30.7%) were specialists, and 89 (29.7%) were residents. The majority were general pediatric consultants. Our study showed that the consultants were more aware of the definition of simple FS in comparison to other groups of physicians, and the difference was statistically significant. However, there was no difference between pediatric neurologists and general pediatricians. There was a statistically significant difference among various specialties in the perceived need to perform routine lumbar puncture, neuroimaging, and serum electrolyte determination in the evaluation of children with FS. On the other hand, there was no difference in the perceived need to perform an electroencephalogram among physicians in different specialties. CONCLUSION The study highlighted the wide variation in knowledge and attitudes of physicians in different specialties with different levels of experience toward the management of FS. The use of clinical practice guidelines will help minimize this diversity.

A novel mutation in ornithine transcarbamylase gene causing mild intermittent hyperammonemia

We report a 3-year-old Saudi boy with recurrent episodes of vomiting, poor feeding, and altered mental status accompanied by an intermittent mild hyperammonemia, and a large elevation of urinary orotic acid. Sanger sequencing of the ornithine transcarbamylase (OTC) gene revealed a novel hemizygous deletion at the fourth nucleotide of intron 4 (c.386+4delT) in the proband and his asymptomatic mother. This novel mutation in the OTC gene is responsible for the late-onset phenotype of OTC deficiency.

Identification of 2 novel homozygous mutations in the methylmalonyl-CoA mutase gene in Saudi patients

The aim of this report is to analyze the clinical features, and mutations of the methylmalonyl CoA mutase (MUT) gene in 2 patients with methylmalonic aciduria (MMA) attending King Saud University Medical City, Riyadh, Saudi Arabia in January 2014. The infants aged 6 days (patient 1) and 3 months (patient 2) with sepsis-like picture, metabolic acidosis, and hyperammonemia were presented. Investigations revealed high propionylcarnitine (C3), elevated urinary methylmalonic acids, 3-hydroxypropionic acids and methylcitrate, consistent with MMA. Sanger-sequencing detected a homozygous novel mutation (c.329A>G; p.Y110C) in the MUT gene in patient 1 and a heterozygous in parents. This mutation is predicted to have a damaging effect on the protein structure and function. In patient 2, we detected a novel homozygous nonsense mutation (c.2200C>T; p.Q734X) and a heterozygous in parents. This mutation leads to a premature stop-codon at codon 734 of the MUT gene. We identified 2 novel mutations in the MUT gene causing isolated MMA.