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LYRM7-associated mitochondrial complex III deficiency with non-cavitating leukoencephalopathy and stroke-like episodes

Alfattal R, Alfarhan M, Algaith AM, Albash B, Elshafie RM, Alshammari A, et al.

Am J Med Genet A, 2023 May;191(5):1401-1411.
PMID: 36757047 DOI: 10.1002/ajmg.a.63143

Defects of respiratory chain complex III (CIII) result in characteristic but rare mitochondrial disorders associated with distinct neuroradiological findings. The underlying molecular defects affecting mitochondrial CIII assembly factors are few and yet to be identified. LYRM7 assembly factor is required for proper CIII assembly where it acts as a chaperone for the Rieske iron-sulfur (UQCRFS1) protein in the mitochondrial matrix and stabilizing it. We present here the seventeenth individual with LYRM7-associated mitochondrial leukoencephalopathy harboring a previously reported rare pathogenic homozygous LYRM 7 variant, c.2T>C, (p.Met1?). Like previously reported individuals, our 5-year-old male proband presented with recurrent metabolic and lactic acidosis, encephalopathy, and fatigue. Further, he has additional, previously unreported features, including an acute stroke like episode with bilateral central blindness and optic neuropathy, recurrent hyperglycemia and hypertension associated with metabolic crisis. However, he has no signs of psychomotor regression. He has been stable clinically with residual left-sided reduced visual acuity and amblyopia, and no more metabolic crises for 2-year-period while on the mitochondrial cocktail. Although the reported brain MRI findings in other affected individuals are homogenous, it is slightly different in our index, revealing evidence of bilateral almost symmetric multifocal periventricular T2 hyperintensities with hyperintensities of the optic nerves, optic chiasm, and corona radiata but with no cavitation or cystic changes. This report describes new clinical and radiological findings of LYRM7-associated disease. The report also summarizes the clinical and molecular data of previously reported individuals describing the full phenotypic spectrum.
Fulltext Challenges to and the future of medication safety in Saudi Arabia: A qualitative study

Aljadhey H, Mahmoud MA, Hassali MA, Alrasheedy A, Alahmad A, Saleem F, et al.

Saudi Pharm J, 2014 Sep;22(4):326-32.
PMID: 25161376 DOI: 10.1016/j.jsps.2013.08.001

BACKGROUND: Medication safety is a global concern among healthcare providers. However, the challenges to and the future of medication safety in Saudi Arabia have not been explored.
OBJECTIVES: We explored the perspectives of healthcare practitioners on current issues about medication safety in hospitals and community settings in Saudi Arabia in order to identify challenges to improving it and explore the future of medication safety practice.
METHODS: A total of 65 physicians, pharmacists, academics and nurses attended a one-day meeting in March 2010, designed especially for the purpose of this study. The participants were divided into nine round-table discussion sessions. Three major themes were explored in these sessions, including: major factors contributing to medication safety problems, challenges to improving medication safety practice, and participants' suggestions for improving medication safety. The round-table discussion sessions were videotaped and transcribed verbatim and analyzed by two independent researchers.
RESULTS: The round-table discussions revealed that major factors contributing to medication safety problems included unrestricted public access to medications from various hospitals and community pharmacies, communication gaps between healthcare institutions, limited use of important technologies such as computerized provider order entry, and the lack of medication safety programs in hospitals. Challenges to current medication safety practice identified by participants included underreporting of medication errors and adverse drug reactions, multilingualism and differing backgrounds of healthcare professionals, lack of communication between healthcare providers and patients, and high workloads. Suggestions for improving medication safety practices in Saudi Arabia included continuous education for healthcare professionals and competency assessment focusing on medication safety, development of a culture that encourages medication error and adverse drug reactions reporting, use of technology proven to decrease medication errors, and promotion and implementation of national patient safety initiatives.
CONCLUSIONS: Healthcare professionals have identified major challenges and opportunities for medication safety in Saudi Arabia. Policy makers and practitioners should consider these factors when designing future programs aimed at improving the safe use of medications.
Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants

Aburezq M, Alahmad A, Alsafi R, Al-Tawari A, Ramadan D, Shafik M, et al.

Orphanet J Rare Dis, 2023 Sep 05;18(1):271.
PMID: 37670342 DOI: 10.1186/s13023-023-02888-y

BACKGROUND: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare autosomal recessive neurometabolic disorder that is caused by biallelic pathogenic SLC19A3 variants and is characterized by subacute encephalopathy associated with confusion, convulsions, dysphagia, dysarthria, or other neurological manifestations.
METHODS: A retrospective review of the data registry in Kuwait Medical Genetics Center for all cases diagnosed clinically and radiographically and confirmed genetically with BTBGD.
RESULTS: Twenty one cases from 13 different families were diagnosed with BTBGD in Kuwait. Most cases (86%) presented with confusion, dystonia, convulsions, or dysarthria, while three individuals were diagnosed pre-symptomatically during familial targeted genetic screening. Symptoms resolved completely within 2-week of treatment in two-thirds of the symptomatic cases but progressed in six of them to a variety of severe symptoms including severe cogwheel rigidity, dystonia and quadriparesis due to delayed presentation and management. Neuroradiological findings of the symptomatic cases revealed bilateral central changes in the basal ganglia. Two novel homozygous missense SLC19A3 variants were detected in a Kuwaiti and a Jordanian individuals, in addition to the previously reported Saudi founder homozygous variant, c.1264A > G; p.(Thr422Ala) in the remaining cases. Age of diagnosis ranged from newborn to 32 years, with a median age of 2-3 years. All cases are still alive receiving high doses of biotin and thiamine.
CONCLUSION: This is the first study reporting the phenotypic and genotypic spectrum of 21 individuals with BTBGD in Kuwait and describing two novel SLC19A3 variants. BTBGD is a treatable neurometabolic disease that requires early recognition and treatment initiation. This study highlights the importance of performing targeted molecular testing of the founder variant in patients presenting with acute encephalopathy in the region.
Fulltext Bi-allelic pathogenic variants in NDUFC2 cause early-onset Leigh syndrome and stalled biogenesis of complex I

Alahmad A, Nasca A, Heidler J, Thompson K, Oláhová M, Legati A, et al.

EMBO Mol Med, 2020 11 06;12(11):e12619.
PMID: 32969598 DOI: 10.15252/emmm.202012619

Leigh syndrome is a progressive neurodegenerative disorder, most commonly observed in paediatric mitochondrial disease, and is often associated with pathogenic variants in complex I structural subunits or assembly factors resulting in isolated respiratory chain complex I deficiency. Clinical heterogeneity has been reported, but key diagnostic findings are developmental regression, elevated lactate and characteristic neuroimaging abnormalities. Here, we describe three affected children from two unrelated families who presented with Leigh syndrome due to homozygous variants (c.346_*7del and c.173A>T p.His58Leu) in NDUFC2, encoding a complex I subunit. Biochemical and functional investigation of subjects' fibroblasts confirmed a severe defect in complex I activity, subunit expression and assembly. Lentiviral transduction of subjects' fibroblasts with wild-type NDUFC2 cDNA increased complex I assembly supporting the association of the identified NDUFC2 variants with mitochondrial pathology. Complexome profiling confirmed a loss of NDUFC2 and defective complex I assembly, revealing aberrant assembly intermediates suggestive of stalled biogenesis of the complex I holoenzyme and indicating a crucial role for NDUFC2 in the assembly of the membrane arm of complex I, particularly the ND2 module.
Fulltext Bi-allelic LETM1 variants perturb mitochondrial ion homeostasis leading to a clinical spectrum with predominant nervous system involvement

Kaiyrzhanov R, Mohammed SEM, Maroofian R, Husain RA, Catania A, Torraco A, et al.

Am J Hum Genet, 2022 Sep 01;109(9):1692-1712.
PMID: 36055214 DOI: 10.1016/j.ajhg.2022.07.007

Leucine zipper-EF-hand containing transmembrane protein 1 (LETM1) encodes an inner mitochondrial membrane protein with an osmoregulatory function controlling mitochondrial volume and ion homeostasis. The putative association of LETM1 with a human disease was initially suggested in Wolf-Hirschhorn syndrome, a disorder that results from de novo monoallelic deletion of chromosome 4p16.3, a region encompassing LETM1. Utilizing exome sequencing and international gene-matching efforts, we have identified 18 affected individuals from 11 unrelated families harboring ultra-rare bi-allelic missense and loss-of-function LETM1 variants and clinical presentations highly suggestive of mitochondrial disease. These manifested as a spectrum of predominantly infantile-onset (14/18, 78%) and variably progressive neurological, metabolic, and dysmorphic symptoms, plus multiple organ dysfunction associated with neurodegeneration. The common features included respiratory chain complex deficiencies (100%), global developmental delay (94%), optic atrophy (83%), sensorineural hearing loss (78%), and cerebellar ataxia (78%) followed by epilepsy (67%), spasticity (53%), and myopathy (50%). Other features included bilateral cataracts (42%), cardiomyopathy (36%), and diabetes (27%). To better understand the pathogenic mechanism of the identified LETM1 variants, we performed biochemical and morphological studies on mitochondrial K+/H+ exchange activity, proteins, and shape in proband-derived fibroblasts and muscles and in Saccharomyces cerevisiae, which is an important model organism for mitochondrial osmotic regulation. Our results demonstrate that bi-allelic LETM1 variants are associated with defective mitochondrial K+ efflux, swollen mitochondrial matrix structures, and loss of important mitochondrial oxidative phosphorylation protein components, thus highlighting the implication of perturbed mitochondrial osmoregulation caused by LETM1 variants in neurological and mitochondrial pathologies.