Aminoglycosides (AGs) are important antibiotics in the treatment of Gram-negative sepsis. However, they are associated with the risk of irreversible sensorineural hearing loss (SNHL). Several genetic ...variants have been implicated in the development of ototoxicity.
To evaluate the pharmacogenetic determinants of AG-related ototoxicity.
This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses and was registered on Prospero (CRD42022337769). In Dec 2022, PubMed, Cochrane Library, Embase and MEDLINE were searched. Included studies were those reporting original data on the effect of the AG-exposed patient's genome on the development of ototoxicity.
Of 10 202 studies, 31 met the inclusion criteria. Twenty-nine studies focused on the mitochondrial genome, while two studied the nuclear genome. One study of neonates found that 30% of those with the m.1555A > G variant failed hearing screening after AG exposure (level 2 evidence). Seventeen additional studies found the m.1555A > G variant was associated with high penetrance (up to 100%) of SNHL after AG exposure (level 3-4 evidence). Nine studies of m.1494C > T found the penetrance of AG-related SNHL to be up to 40%; however, this variant was also identified in those with SNHL without AG exposure (level 3-4 evidence). The variants m.1005T > C and m.1095T > C may be associated with AG-related SNHL; however, further studies are needed.
This review found that the m.1555A > G and m.1494C > T variants in the MT-RNR1 gene have the strongest evidence in the development of AG-related SNHL, although study quality was limited (level 2-4). These variants were associated with high penetrance of a SNHL phenotype following AG exposure.
Introduction
Perinatal depression and sleep difficulties are common among studies conducted in high income countries (HIC). This study examines the relationship between sleep difficulties and ...depression during the perinatal period and over an eight-year follow-up period in South Africa, a middle income country.
Method
A population cohort of 1238 pregnant women (mean age = 26.33) in 24 township neighborhoods in South Africa were recruited and reassessed six times over the next 8 years post birth with follow-up rates of 96–83%. The relationship between maternal depressed mood and sleep difficulties was examined over time, as well as the relationship of sleep with other socioeconomic, environmental, and psychiatric risk factors.
Results
Thirty-five percent of the women reported sleep difficulties during the perinatal period; whereas only 8% reported sleep difficulties at 8-year follow-up. Perinatal sleep difficulties were associated with lower income, lower educational attainment, less access to electricity, more food insecurity, higher rates of interpersonal violence and HIV, alcohol consumption, and depressed mood at 8 years. However, the severity of depressed mood was the strongest predictor of sleep problems longitudinally and cross-sectionally, after accounting for all other risk factors.
Conclusions
We found that the severity of depressed mood is highly associated with sleep difficulties from pregnancy to 8 years post-birth and in a linear relationship, so that higher depressed mood is associated with more sleep problems.
Trial Registration:
ClinicalTrials.gov registration: # NCT00996528.
Significance
Sleep is understudied among people living in poverty in LMIC’s. To our knowledge this is the first study to (a) investigate the relationship between sleep difficulties and depression in a sample of high-risk, black women living in poverty in a LMIC and (b) study the relationship between sleep and depression continuously from the perinatal period through 8 years post-partum in a LMIC. The study finds that sleep difficulties and depression are highly correlated during this period even after accounting for other socioeconomic, environmental and psychiatric risk factors in this high-risk population.
About 250 million children under the age of 5 years in low- and middle-income countries (LMICs) lose lifelong cognitive potential. However, the primary focus of interventions has been to increase ...survival and promote growth. All pregnant women in 24 non-contiguous, low-income areas in Cape Town, South Africa (N=1 238) were recruited between 2009 and 2010 and reassessed six times over 8 years post birth. Mothers in half of the 24 areas were randomised to receive home visits by community health workers, concentrated during the pregnancy and the first 6 months of life. At 18 months, the children’s cognitive development was at the global norm, i.e a mean standard deviation (SD) value of 100 (15). By 5 years of age, the mean cognitive development fell to one SD below the global norm (<85; mean = 83) and 60% of children had scores below the global mean. By 8 years of age, cognitive development scores significantly fell again (mean = 73; 88% of children <85). The magnitude of the loss was substantial and warrants sustained interventions throughout childhood that support children’s cognitive development in LMICs. The first 1 00 days of life are important, but insufficient to inoculate children against the negative consequences of poverty and coping with multiple, chronic community challenges (e.g. HIV, alcohol abuse, interpersonal violence)
Hyperekplexia is a rare, but potentially fatal, neuromotor disorder characterized by exaggerated startle reflexes and hypertonia in response to sudden, unexpected auditory or tactile stimuli. This ...disorder is primarily caused by inherited mutations in the genes encoding the glycine receptor (GlyR) alpha1 subunit (GLRA1) and the presynaptic glycine transporter GlyT2 (SLC6A5). In this study, systematic DNA sequencing of GLRA1 in 88 new unrelated human hyperekplexia patients revealed 19 sequence variants in 30 index cases, of which 21 cases were inherited in recessive or compound heterozygote modes. This indicates that recessive hyperekplexia is far more prevalent than previous estimates. From the 19 GLRA1 sequence variants, we have investigated the functional effects of 11 novel and 2 recurrent mutations. The expression levels and functional properties of these hyperekplexia mutants were analyzed using a high-content imaging system and patch-clamp electrophysiology. When expressed in HEK293 cells, either as homomeric alpha1 or heteromeric alpha1beta GlyRs, subcellular localization defects were the major mechanism underlying recessive mutations. However, mutants without trafficking defects typically showed alterations in the glycine sensitivity suggestive of disrupted receptor function. This study also reports the first hyperekplexia mutation associated with a GlyR leak conductance, suggesting tonic channel opening as a new mechanism in neuronal ligand-gated ion channels.
Clinical finding of cutis laxa, characterized by wrinkled, redundant, sagging, nonelastic skin, is of growing significance due to its occurrence in several different inborn errors of metabolism ...(IEM). Metabolic cutis laxa results from Menkes syndrome, caused by a defect in the ATPase copper transporting alpha (ATP7A) gene; congenital disorders of glycosylation due to mutations in subunit 7 of the component of oligomeric Golgi (COG7)–congenital disorders of glycosylation (CDG) complex; combined disorder of N- and O-linked glycosylation, due to mutations in ATPase H+ transporting V0 subunit a2 (ATP6VOA2) gene; pyrroline-5-carboxylate reductase 1 deficiency; pyrroline-5-carboxylate synthase deficiency; macrocephaly, alopecia, cutis laxa, and scoliosis (MACS) syndrome, due to Ras and Rab interactor 2 (RIN2) mutations; transaldolase deficiency caused by mutations in the transaldolase 1 (TALDO1) gene; Gerodermia osteodysplastica due to mutations in the golgin, RAB6-interacting (GORAB or SCYL1BP1) gene; and mitogen-activated pathway (MAP) kinase defects, caused by mutations in several genes protein tyrosine phosphatase, non-receptor-type 11 (PTPN11), RAF, NF, HRas proto-oncogene, GTPase (HRAS), B-Raf proto-oncogene, serine/threonine kinase (BRAF), MEK1/2, KRAS proto-oncogene, GTPase (KRAS), SOS Ras/Rho guanine nucleotide exchange factor 2 (SOS2), leucine rich repeat scaffold protein (SHOC2), NRAS proto-oncogene, GTPase (NRAS), and Raf-1 proto-oncogene, serine/threonine kinase (RAF1), which regulate the Ras-MAPK cascade. Here, we further expand the list of inborn errors of metabolism associated with cutis laxa by describing the clinical presentation of a 17-month-old girl with Leigh-like syndrome due to enoyl coenzyme A hydratase, short chain, 1, mitochondria (ECHS1) deficiency, a mitochondrial matrix enzyme that catalyzes the second step of the beta-oxidation spiral of fatty acids and plays an important role in amino acid catabolism, particularly valine.
The differential diagnostics in Rett syndrome has evolved with the development of next generation sequencing‐based techniques and many patients have been diagnosed with other syndromes or variants in ...newly described genes where the associated phenotype(s) is yet to be fully explored. The term Rett‐like refers to phenotypes with distinct overlapping features of Rett syndrome where the clinical criteria are not completely fulfilled. In this study we have combined a review of Rett‐like disorders with data from a Danish cohort of 35 patients with Rett‐like phenotypes emphasizing the diagnostic overlap with Pitt‐Hopkins syndrome, Cornelia de Lange syndrome with SMC1A variants, and epileptic encephalopathies, for example, due to STXBP1 variants. We also found a patient with a pathogenic variant in KCNB1, which has not been previously linked to a Rett‐like phenotype. This study underlines the clinical and genetic heterogeneity of a Rett syndrome spectrum, and provides an overview of the Rett syndrome‐related genes described to date, and hence serves as a guide for diagnosing patients with Rett‐like phenotypes.
Exploring the genes in Rett‐like phenotypes.
This study aimed to compare the phenotype of Rett syndrome cases with C-terminal deletions to that of cases with different MECP2 mutations and to examine the phenotypic variation within C-terminal ...deletions.
Cases were selected from InterRett, an international database and from the population-based Australian Rett Syndrome Database. Cases (n=832) were included if they had a pathogenic MECP2 mutation in which the nature of the amino acid change was known. Three severity scale systems were used, and individual aspects of the phenotype were also compared.
Lower severity was associated with C-terminal deletions (n=79) compared to all other MECP2 mutations (e.g. Pineda scale C-terminals mean 15.0 (95% CI 14.0-16.0) vs 16.2 (15.9-16.5). Cases with C-terminal deletions were more likely to have a normal head circumference (odds ratio 3.22, 95% CI 1.53 - 6.79) and weight (odds ratio 2.97, 95% CI 1.25-5.76). Onset of stereotypies tended to be later (median age 2.5 years vs 2 years, p<0.001 from survival analysis), and age of learning to walk tended to be earlier (median age 1.6 years vs 2 years, p=0.002 from survival analysis). Those with C-terminal deletions occurring later in the region had lower average severity scores than those occurring earlier in the region.
In terms of overall severity C-terminal deletion cases would appear to be in the middle of the range. In terms of individual aspects of phenotype growth and ability to ambulate appear to be particular strengths. By pooling data internationally this study has achieved the case numbers to provide a phenotypic profile of C-terminal deletions in Rett syndrome.
Inborn errors of metabolism are collectively common, frequently severe and in many instances difficult or impossible to treat. Accordingly, there is a compelling need to explore novel therapeutic ...modalities, including gene therapy, and examine multiple phenotypes where the risks of experimental therapy are outweighed by potential benefits to trial participants. Among available gene delivery systems recombinant AAV shows special promise for the treatment of metabolic disease given the unprecedented efficiencies achieved in transducing key target tissues, such as liver and muscle, in small animal models. To date over 30 metabolic disease phenotypes have been investigated in small animal studies with complete phenotype correction being achieved in a substantial proportion. Achieving adequately widespread transduction within the central nervous system, however, remains a major challenge, and will be critical to realization of the therapeutic potential of gene therapy for many of the most clinically troubling metabolic disease phenotypes. Despite the relatively low immunogenicity of AAV vectors, immune responses are also emerging as a factor requiring special attention as efforts accelerate toward human clinical translation. Four metabolic disease phenotypes have reached phase I or I/II trials with one, targeting lipoprotein lipase deficiency, showing exciting early evidence of efficacy.
Rett syndrome (RTT) is a severe neurodevelopmental disorder, predominantly caused by mutations in the X-linked Methyl-CpG-binding protein 2 (MECP2) gene. Patients present with numerous functional ...deficits including intellectual disability and abnormalities of movement. Clinical and biochemical features may overlap with those seen in patients with primary mitochondrial respiratory chain disorders. In the late stages of the disorder, patients suffer from motor deterioration and usually require assisted mobility. Using a mouse model of RTT (Mecp2(tm1Tam)), we studied the mitochondrial function in the hind-limb skeletal muscle of these mice. We identified a reduction in cytochrome c oxidase subunit I (MTCO1) at both the transcript and protein level, in accordance with our previous findings in RTT patient brain studies. Mitochondrial respiratory chain (MRC) enzyme activity of complexes II+III (COII+III) and complex IV (COIV), and glutathione (GSH) levels were significantly reduced in symptomatic mice, but not in the pre-symptomatic mice. Our findings suggest that mitochondrial abnormalities in the skeletal muscle may contribute to the progressive deterioration in mobility in RTT through the accumulation of free radicals, as evidenced by the decrease in reduced glutathione (GSH). We hypothesise that a diminution in GSH leads to an accumulation of free radicals and an increase in oxidative stress. This may impact on respiratory chain function and contribute in part to the progressive neurological and motor deterioration seen in the Mecp2-mutant mouse. Treatment strategies aimed at restoring cellular GSH levels may prove to be a novel target area to consider in future approaches to RTT therapies.
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