RESUMEN
PURPOSE: Genetic variants causing aberrant premessenger RNA splicing are increasingly being recognized as causal variants in genetic disorders. In this study, we devise standardized practices for polymerase chain reaction (PCR)-based RNA diagnostics using clinically accessible specimens (blood, fibroblasts, urothelia, biopsy). METHODS: A total of 74 families with diverse monogenic conditions (31% prenatal-congenital onset, 47% early childhood, and 22% teenage-adult onset) were triaged into PCR-based RNA testing, with comparative RNA sequencing for 19 cases. RESULTS: Informative RNA assay data were obtained for 96% of cases, enabling variant reclassification for 75% variants that can be used for genetic counseling (71%), to inform clinical care (32%) and prenatal counseling (41%). Variant-associated mis-splicing was highly reproducible for 28 cases with samples from ≥2 affected individuals or heterozygotes and 10 cases with ≥2 biospecimens. PCR amplicons encompassing another segregated heterozygous variant was vital for clinical interpretation of 22 of 79 variants to phase RNA splicing events and discern complete from partial mis-splicing. CONCLUSION: RNA diagnostics enabled provision of a genetic diagnosis for 64% of recruited cases. PCR-based RNA diagnostics has capacity to analyze 81.3% of clinically significant genes, with long amplicons providing an advantage over RNA sequencing to phase RNA splicing events. The Australasian Consortium for RNA Diagnostics (SpliceACORD) provide clinically-endorsed, standardized protocols and recommendations for interpreting RNA assay data.
Asunto(s)
Empalme del ARN , ARN , Adolescente , Adulto , Preescolar , Humanos , Mutación , ARN/genética , Empalme del ARN/genética , Análisis de Secuencia de ARN , Secuenciación del ExomaRESUMEN
BACKGROUND: In the clinical setting, identification of the genetic cause in patients with early-onset dementia (EOD) is challenging due to multiple types of genetic tests required to arrive at a diagnosis. Whole-genome sequencing (WGS) has the potential to serve as a single diagnostic platform, due to its superior ability to detect common, rare and structural genetic variation. METHODS: WGS analysis was performed in 50 patients with EOD. Point mutations, small insertions/deletions, as well as structural variants (SVs) and short tandem repeats (STRs), were analysed. An Alzheimer's disease (AD)-related polygenic risk score (PRS) was calculated in patients with AD. RESULTS: Clinical genetic diagnosis was achieved in 7 of 50 (14%) of the patients, with a further 8 patients (16%) found to have established risk factors which may have contributed to their EOD. Two pathogenic variants were identified through SV analysis. No expanded STRs were found in this study cohort, but a blinded analysis with a positive control identified a C9orf72 expansion accurately. Approximately 37% (7 of 19) of patients with AD had a PRS equivalent to >90th percentile risk. DISCUSSION: WGS acts as a single genetic test to identify different types of clinically relevant genetic variations in patients with EOD. WGS, if used as a first-line clinical diagnostic test, has the potential to increase the diagnostic yield and reduce time to diagnosis for EOD.
RESUMEN
OBJECTIVE: When a genetic cause is suspected in a person with dementia, it creates unique diagnostic and management challenges to the treating clinician. Many clinicians may be unaware of the practicalities surrounding genetic testing for their patients, such as when to test and what tests to use and how to counsel patients and their families. This review was conducted to provide guidance to clinicians caring for patients with dementia regarding clinically relevant genetics. METHODS: We searched PubMed for studies that involved genetics of dementia up to March 2020. Patient file reviews were also conducted to create composite cases. RESULTS: In addition to families where a strong Mendelian pattern of family history is seen, people with younger age of onset, especially before the age of 65 years were found to be at an increased risk of harbouring a genetic cause for their dementia. This review discusses some of the most common genetic syndromes, including Alzheimer disease, frontotemporal dementia, vascular dementia, Parkinson disease dementia/dementia with Lewy bodies and some rarer types of genetic dementias, along with illustrative clinical case studies. This is followed by a brief review of the current genetic technologies and a discussion on the unique genetic counselling issues in dementia. CONCLUSIONS: Inclusion of genetic testing in the diagnostic pathway in some patients with dementia could potentially reduce the time taken to diagnose the cause of their dementia. Although a definite advantage as an addition to the diagnostic repository, genetic testing has many pros and cons which need to be carefully considered first.
Asunto(s)
Enfermedad de Alzheimer , Demencia Vascular , Demencia Frontotemporal , Genética Médica , Anciano , Enfermedad de Alzheimer/genética , Pruebas Genéticas , HumanosRESUMEN
The rapid evolution and wide applicability of genomic testing means that medical practitioners outside the field are not appropriately skilled to understand the utility of genomics for their patients. Rotating junior doctors through genomic medicine provides them with the hands-on experience necessary to understand the complexities in this field. In this study, we analysed the training experience of 12 hospital medical officers who rotated through genomic medicine at the Royal Melbourne Hospital. Here, we demonstrate that immersion in clinical genomics aids in mainstreaming genomics knowledge.
Asunto(s)
Genómica , Medicina , Curriculum , Hospitales , Humanos , Cuerpo Médico de HospitalesRESUMEN
In the original version of this Article, the affiliation details for Lei Zhang were given as Monash University. While working on the Article Dr. Zhang was also affiliated with the Department of Epidemiology and Biostatistics, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, PR China. This has now been corrected in both the PDF and HTML versions of the Article.
RESUMEN
PURPOSE: To consider the impact and cost-effectiveness of offering preventive population genomic screening to all young adults in a single-payer health-care system. METHODS: We modeled screening of 2,688,192 individuals, all adults aged 18-25 years in Australia, for pathogenic variants in BRCA1/BRCA2/MLH1/MSH2 genes, and carrier screening for cystic fibrosis (CF), spinal muscular atrophy (SMA), and fragile X syndrome (FXS), at 71% testing uptake using per-test costs ranging from AUD$200 to $1200 (~USD$140 to $850). Investment costs included genetic counseling, surveillance, and interventions (reimbursed only) for at-risk individuals/couples. Cost-effectiveness was defined below AUD$50,000/DALY (disability-adjusted life year) prevented, using an incremental cost-effectiveness ratio (ICER), compared with current targeted testing. Outcomes were cancer incidence/mortality, disease cases, and treatment costs reduced. RESULTS: Population screening would reduce variant-attributable cancers by 28.8%, cancer deaths by 31.2%, and CF/SMA/FXS cases by 24.8%, compared with targeted testing. Assuming AUD$400 per test, investment required would be between 4 and 5 times higher than current expenditure. However, screening would lead to substantial savings in medical costs and DALYs prevented, at a highly cost-effective ICER of AUD$4038/DALY. At AUD$200 per test, screening would approach cost-saving for the health system (ICER = AUD$22/DALY). CONCLUSION: Preventive genomic screening in early adulthood would be highly cost-effective in a single-payer health-care system, but ethical issues must be considered.
Asunto(s)
Fibrosis Quística/diagnóstico , Síndrome del Cromosoma X Frágil/diagnóstico , Atrofia Muscular Espinal/diagnóstico , Neoplasias/diagnóstico , Adolescente , Adulto , Australia/epidemiología , Proteína BRCA1/genética , Proteína BRCA2/genética , Análisis Costo-Beneficio/economía , Fibrosis Quística/epidemiología , Fibrosis Quística/genética , Atención a la Salud/economía , Femenino , Síndrome del Cromosoma X Frágil/epidemiología , Síndrome del Cromosoma X Frágil/genética , Humanos , Masculino , Metagenómica/economía , Atrofia Muscular Espinal/epidemiología , Atrofia Muscular Espinal/genética , Homólogo 1 de la Proteína MutL/genética , Proteína 2 Homóloga a MutS/genética , Neoplasias/epidemiología , Neoplasias/genética , Años de Vida Ajustados por Calidad de Vida , Adulto JovenRESUMEN
INTRODUCTION: Individuals with homozygosity for the apolipoprotein E (APOE) ε4 allele are in the highest risk category for late-onset Alzheimer's disease (LOAD). However, some individuals in this category do not develop LOAD beyond the age of 75 years, despite being at elevated genetic risk. These "resilient" individuals may carry protective genetic factors. METHODS: This study aimed to systematically review any previous studies that involved resilient APOE ε4 homozygotes and to identify possible modifying or protective genetic factors. RESULTS: Fifteen studies met our inclusion criteria and reported genetic factors contributing to reduced risk. We found that only two single nucleotide polymorphisms, CASP7 rs10553596 and SERPINA3 rs4934-A/A, had strong evidence. DISCUSSION: We found a paucity of studies adequately designed to discover protective genetic factors against LOAD. Many studies combined APOE ε4 homozygotes and heterozygotes together because of small sample sizes and used control populations too young to be clearly defined as controls for LOAD.
Asunto(s)
Enfermedad de Alzheimer , Apolipoproteína E4/genética , Homocigoto , Factores Protectores , Alelos , Enfermedad de Alzheimer/epidemiología , Enfermedad de Alzheimer/genética , Humanos , Polimorfismo de Nucleótido Simple , Factores de RiesgoRESUMEN
OBJECTIVE: Friedreich ataxia (FRDA) is an inherited neurodegenerative disease characterized by ataxia and cardiomyopathy. Homozygous GAA trinucleotide repeat expansions in the first intron of FXN occur in 96% of affected individuals and reduce frataxin expression. Remaining individuals are compound heterozygous for a GAA expansion and a FXN point/insertion/deletion mutation. We examined disease-causing mutations and the impact on frataxin structure/function and clinical outcome in FRDA. METHODS: We compared clinical information from 111 compound heterozygotes and 131 individuals with homozygous expansions. Frataxin mutations were examined using structural modeling, stability analyses and systematic literature review, and categorized into four groups: (1) homozygous expansions, and three compound heterozygote groups; (2) null (no frataxin produced); (3) moderate/strong impact; and (4) minimal impact. Mean age of onset and the presence of cardiomyopathy and diabetes mellitus were compared using regression analyses. RESULTS: Mutations in the hydrophobic core of frataxin affected stability whereas surface residue mutations affected interactions with iron sulfur cluster assembly and heme biosynthetic proteins. The null group of compound heterozygotes had significantly earlier age of onset and increased diabetes mellitus, compared to the homozygous expansion group. There were no significant differences in mean age of onset between homozygotes and the minimal and moderate/strong impact groups. INTERPRETATION: In compound heterozygotes, expression of partially functional mutant frataxin delays age of onset and reduces diabetes mellitus, compared to those with no frataxin expression from the non-expanded allele. This integrated analysis of categorized frataxin mutations and their correlation with clinical outcome provide a definitive resource for investigating disease pathogenesis in FRDA.
Asunto(s)
Diabetes Mellitus/epidemiología , Diabetes Mellitus/genética , Ataxia de Friedreich/epidemiología , Ataxia de Friedreich/genética , Proteínas de Unión a Hierro/genética , Pérdida de Heterocigocidad/genética , Adolescente , Adulto , Distribución por Edad , Causalidad , Niño , Preescolar , Comorbilidad , Femenino , Marcadores Genéticos/genética , Predisposición Genética a la Enfermedad/epidemiología , Predisposición Genética a la Enfermedad/genética , Humanos , Incidencia , Lactante , Masculino , Pronóstico , Factores de Riesgo , Distribución por Sexo , Victoria/epidemiología , Adulto Joven , FrataxinaRESUMEN
BACKGROUND: Gorlin syndrome (nevoid basal cell carcinoma syndrome) is a rare genetic predisposition to basal cell carcinomas (BCC), keratocysts of the jaw and calcification of the falx cerebri among other clinical features. With the advent of sonic hedgehog inhibitors for the treatment of BCC, it is timely to establish a cohort of individuals with Gorlin syndrome and collect standardised phenotypic information on these individuals. Moreover, the health-related quality of life (QoL) in individuals with Gorlin syndrome is not well studied. AIM: To establish a Victorian cohort of Gorlin syndrome and study the QoL in these individuals. METHODS: Phenotypic data were obtained by reviewing medical records of individuals attending two major tertiary/quaternary genetic referral centres in Victoria, followed by telephone or face-to-face interviews where possible. QoL information was obtained utilising the AQoL-6D quality of life survey form. RESULTS: The median number of BCC in the 19 individuals studied was 17.5 (interquartile range 3-70). The number of patients with ≥100 BCC in this group was similar to a previously described national cohort (22.2 vs 27% respectively). A total of 58% of referrals to the genetics clinics originated from maxillofacial surgeons and 42% from dermatologists. Individuals with ≥100 BCC had worse median QoL scores compared to those with <100 BCC (36 vs 29, P-value of 0.031). CONCLUSION: The clinical features in our cohort were congruent with those previously described in Australia. The QoL is adversely correlated with increased BCC burden.
Asunto(s)
Síndrome del Nevo Basocelular/diagnóstico , Síndrome del Nevo Basocelular/psicología , Carcinoma Basocelular/diagnóstico , Carcinoma Basocelular/psicología , Fenotipo , Calidad de Vida/psicología , Adolescente , Adulto , Anciano , Síndrome del Nevo Basocelular/epidemiología , Carcinoma Basocelular/epidemiología , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Victoria/epidemiología , Adulto JovenRESUMEN
INTRODUCTION: Young onset dementia (YOD) by its nature is difficult to diagnose. Despite involvement of multidisciplinary neurogenetics services, patients with YOD and their families face significant diagnostic delays. Genetic testing for people with YOD currently involves a staggered, iterative approach. There is currently no optimal single genetic investigation that simultaneously identifies the different genetic variants resulting in YOD. AREAS COVERED: This review discusses the advances in clinical genomic testing for people with YOD. Whole genome sequencing (WGS) can be employed as a 'one stop shop' genomic test for YOD. In addition to single nucleotide variants, WGS can reliably detect structural variants, short tandem repeat expansions, mitochondrial genetic variants as well as capture single nucleotide polymorphisms for the calculation of polygenic risk scores. EXPERT OPINION: WGS, when used as the initial genetic test, can enhance the likelihood of a precision diagnosis and curtail the time taken to reach this. Finding a clinical diagnosis using WGS can reduce invasive and expensive investigations and could be cost effective. These advances need to be balanced against the limitations of the technology and the genetic counseling needs for these vulnerable patients and their families.
RESUMEN
This study evaluated patient experiences with genetic testing for inherited retinal diseases (IRDs) and the association between underlying knowledge, testing outcomes, and the perceived value of the results. An online survey was distributed to adults with IRDs and parents/guardians of dependents with IRDs who had had genetic testing. Data included details of genetic testing, pre- and post- test perceptions, Decision Regret Scale, perceived value of results, and knowledge of gene therapy. Of 135 responses (85% from adults with IRDs), genetic testing was primarily conducted at no charge through public hospitals (49%) or in a research setting (30%). Key motivations for genetic testing were to confirm IRD diagnosis and to contribute towards research. Those who had received a genetic diagnosis (odds ratio: 6.71; p < 0.001) and those self-reported to have good knowledge of gene therapy (odds ratio: 2.69; p = 0.018) were more likely to have gained confidence in managing their clinical care. For over 80% of respondents, knowing the causative gene empowered them to learn more about their IRD and explore opportunities regarding clinical trials. Key genetic counselling information needs include resources for family communications, structured information provision, and ongoing genetic support, particularly in the context of emerging ocular therapies, to enhance consistency in information uptake.
Asunto(s)
Retina , Enfermedades de la Retina , Adulto , Humanos , Estudios Transversales , Enfermedades de la Retina/diagnóstico , Enfermedades de la Retina/genética , Enfermedades de la Retina/terapia , Pruebas Genéticas , Aprendizaje , Evaluación del Resultado de la Atención al PacienteRESUMEN
BACKGROUND: Significant recent efforts have facilitated increased access to clinical genetics assessment and genomic sequencing for children with rare diseases in many centres, but there remains a service gap for adults. The Austin Health Adult Undiagnosed Disease Program (AHA-UDP) was designed to complement existing UDP programs that focus on paediatric rare diseases and address an area of unmet diagnostic need for adults with undiagnosed rare conditions in Victoria, Australia. It was conducted at a large Victorian hospital to demonstrate the benefits of bringing genomic techniques currently used predominantly in a research setting into hospital clinical practice, and identify the benefits of enrolling adults with undiagnosed rare diseases into a UDP program. The main objectives were to identify the causal mutation for a variety of diseases of individuals and families enrolled, and to discover novel disease genes. METHODS: Unsolved patients in whom standard genomic diagnostic techniques such as targeted gene panel, exome-wide next generation sequencing, and/or chromosomal microarray, had already been performed were recruited. Genome sequencing and enhanced genomic analysis from the research setting were applied to aid novel gene discovery. RESULTS: In total, 16/50 (32%) families/cases were solved. One or more candidate variants of uncertain significance were detected in 18/50 (36%) families. No candidate variants were identified in 16/50 (32%) families. Two novel disease genes (TOP3B, PRKACB) and two novel genotype-phenotype correlations (NARS, and KMT2C genes) were identified. Three out of eight patients with suspected mosaic tuberous sclerosis complex had their diagnosis confirmed which provided reproductive options for two patients. The utility of confirming diagnoses for patients with mosaic conditions (using high read depth sequencing and ddPCR) was not specifically envisaged at the onset of the project, but the flexibility to offer recruitment and analyses on an as-needed basis proved to be a strength of the AHA-UDP. CONCLUSION: AHA-UDP demonstrates the utility of a UDP approach applying genome sequencing approaches in diagnosing adults with rare diseases who have had uninformative conventional genetic analysis, informing clinical management, recurrence risk, and recommendations for relatives.
Asunto(s)
Enfermedades Raras , Humanos , Adulto , Femenino , Masculino , Australia , Enfermedades Raras/genética , Enfermedades Raras/diagnóstico , Enfermedades no Diagnosticadas/genética , Enfermedades no Diagnosticadas/diagnóstico , Pruebas Genéticas/métodos , Persona de Mediana Edad , Adulto JovenRESUMEN
PURPOSE: Accurate genotyping of individuals with inherited retinal diseases (IRD) is essential for patient management and identifying suitable candidates for gene therapies. This study evaluated the diagnostic yield of next generation sequencing (NGS) in IRDs. DESIGN: Systematic review and meta-analysis. METHODS: This systematic review was prospectively registered (CRD42021293619). Ovid MEDLINE and Ovid Embase were searched on 6 June 2022. Clinical studies evaluating the diagnostic yield of NGS in individuals with IRDs were eligible for inclusion. Risk of bias assessment was performed. Studies were pooled using a random...effects inverse variance model. Sources of heterogeneity were explored using stratified analysis, meta-regression, and sensitivity analysis. RESULTS: This study included 105 publications from 28 countries. Most studies (90 studies) used targeted gene panels. The diagnostic yield of NGS was 61.3% (95% confidence interval: 57.8-64.7%; 51 studies) in mixed IRD phenotypes, 58.2% (51.6-64.6%; 41 studies) in rod-cone dystrophies, 57.7% (46.8-68.3%; eight studies) in macular and cone/cone-rod dystrophies, and 47.6% (95% CI: 41.0-54.3%; four studies) in familial exudative vitreoretinopathy. For mixed IRD phenotypes, a higher diagnostic yield was achieved pooling studies published between 2018-2022 (64.2% [59.5-68.7%]), studies using exome sequencing (73.5% [58.9-86.1%]), and studies using the American College of Medical Genetics variant interpretation standards (65.6% [60.8-70.4%]). CONCLUSION: The current diagnostic yield of NGS in IRDs is between 52-74%. The certainty of the evidence was judged as low or very low. A key limitation of the current evidence is the significant heterogeneity between studies. Adoption of standardized reporting guidelines could improve confidence in future meta-analyses.
Asunto(s)
Distrofias de Conos y Bastones , Enfermedades de la Retina , Humanos , Secuenciación de Nucleótidos de Alto Rendimiento , Enfermedades de la Retina/diagnóstico , Enfermedades de la Retina/genética , Retina , FenotipoRESUMEN
Few studies have measured the effect of genetic factors on dementia and cognitive decline in healthy older individuals followed prospectively. We studied cumulative incidence of dementia and cognitive decline, stratified by APOE genotypes and polygenic risk score (PRS) tertiles, in 12,978 participants of the ASPirin in Reducing Events in the Elderly (ASPREE) trial. At enrolment, participants had no history of diagnosed dementia, cardiovascular disease, physical disability or cognitive impairment. Dementia (adjudicated trial endpoint) and cognitive decline, defined as a >1.5 standard deviation decline in test score for either global cognition, episodic memory, language/executive function or psychomotor speed, versus baseline scores. Cumulative incidence for all-cause dementia and cognitive decline was calculated with mortality as a competing event, stratified by APOE genotypes and tertiles of a PRS based on 23 common non-APOE variants. During a median 4.5 years of follow-up, 324 participants developed dementia, 503 died. Cumulative incidence of dementia to age 85 years was 7.4% in all participants, 12.6% in APOE ε3/ε4 and 26.6% in ε4/ε4. APOE ε4 heterozygosity/homozygosity was associated with a 2.5/6.3-fold increased dementia risk and 1.4/1.8-fold cognitive decline risk, versus ε3/ε3 (p < 0.001 for both). High PRS tertile was associated with a 1.4-fold dementia risk versus low (CI 1.04-1.76, p = 0.02), but was not associated with cognitive decline (CI 0.96-1.22, p = 0.18). Incidence of dementia among healthy older individuals is low across all genotypes; however, APOE ε4 and high PRS increase relative risk. APOE ε4 is associated with cognitive decline, but PRS is not.
Asunto(s)
Apolipoproteína E4/metabolismo , Disfunción Cognitiva/genética , Demencia/genética , Factores de Edad , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Factores de RiesgoRESUMEN
INTRODUCTION: Diversity in cognition among apolipoprotein E (APOE) ε4 homozygotes can range from early-onset Alzheimer's disease (AD) to a lifetime with no symptoms. METHODS: We evaluated a phenotypic extreme polygenic risk score (PRS) for AD between cognitively healthy APOE ε4 homozygotes aged ≥75 years (n = 213) and early-onset APOE ε4 homozygote AD cases aged ≤65 years (n = 223) as an explanation for this diversity. RESULTS: The PRS for AD was significantly higher in APOE ε4 homozygote AD cases compared to older cognitively healthy APOE ε4/ε4 controls (odds ratio [OR] 8.39; confidence interval [CI] 2.0-35.2; P = .003). The difference in the same PRS between APOE ε3/ε3 extremes was not as significant (OR 3.13; CI 0.98-9.92; P = .053) despite similar numbers and power. There was no statistical difference in an educational attainment PRS between these age extreme case-controls. DISCUSSION: A PRS for AD contributes to modified cognitive expression of the APOE ε4/ε4 genotype at phenotypic extremes of risk.
RESUMEN
Currently there is no secured ongoing funding in Australia for next generation sequencing (NGS) such as exome sequencing (ES) for adult neurological disorders. Studies have focused on paediatric populations in research or highly specialised settings, utilised standard NGS pipelines focusing only on small insertions, deletions and single nucleotide variants, and not explored impacts on management in detail. This prospective multi-site study performed ES and an extended bioinformatics repeat expansion analysis pipeline, on patients with broad phenotypes (ataxia, dementia, dystonia, spastic paraparesis, motor neuron disease, Parkinson's disease and complex/not-otherwise-specified), with symptom onset between 2 and 60 years. Genomic data analysis was phenotype-driven, using virtual gene panels, reported according to American College of Medical Genetics and Genomics guidelines. One-hundred-and-sixty patients (51% female) were included, median age 52 years (range 14-79) and median 9 years of symptoms. 34/160 (21%) patients received a genetic diagnosis. Highest diagnostic rates were in spastic paraparesis (10/25, 40%), complex/not-otherwise-specified (10/38, 26%) and ataxia (7/28, 25%) groups. Findings were considered 'possible/uncertain' in 21/160 patients. Repeat expansion detection identified an unexpected diagnosis of Huntington disease in an ataxic patient with negative ES. Impacts on management, such as more precise and tailored care, were seen in most diagnosed patients (23/34, 68%). ES and a novel bioinformatics analysis pipepline had a substantial diagnostic yield (21%) and management impacts for most diagnosed patients, in heterogeneous, complex, mainly adult-onset neurological disorders in real-world settings in Australia, providing evidence for NGS and complementary multiple, new technologies as valuable diagnostic tools.
Asunto(s)
Exoma , Pruebas Genéticas , Adolescente , Adulto , Anciano , Australia , Niño , Biología Computacional , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Estudios Prospectivos , Adulto JovenRESUMEN
Autosomal dominant optic atrophy (ADOA) is a neuro-ophthalmic condition characterized by bilateral degeneration of the optic nerves. Although heterozygous mutations in OPA1 represent the most common genetic cause of ADOA, a significant number of cases remain undiagnosed.Here, we describe a family with a strong ADOA history with most family members spanning three generation having childhood onset of visual symptoms. The proband, in addition to optic atrophy, had neurological symptoms consistent with relapsing remitting multiple sclerosis. Clinical exome analysis detected a novel mutation in the AFG3L2 gene (NM_006796.2:c.1010G > A; p.G337E), which segregated with optic atrophy in family members. AFG3L2 is a metalloprotease of the AAA subfamily which exerts quality control in the inner mitochondrial membrane. Interestingly, the identified mutation localizes close to the AAA domain of AFG3L2, while those localized in the proteolytic domain cause dominant spinocerebellar ataxia type 28 (SCA28) or recessive spastic ataxia with epilepsy (SPAX5). Functional studies in patient fibroblasts demonstrate that the p.G337E AFG3L2 mutation strongly destabilizes the long isoforms of OPA1 via OMA hyper-activation and leads to mitochondrial fragmentation, thus explaining the family phenotype. This study widens the clinical spectrum of neurodegenerative diseases caused by AFG3L2 mutations, which shall be considered as genetic cause of ADOA.
Asunto(s)
Proteasas ATP-Dependientes/genética , ATPasas Asociadas con Actividades Celulares Diversas/genética , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Dominio AAA/genética , Adolescente , Niño , Preescolar , Femenino , GTP Fosfohidrolasas/metabolismo , Humanos , Masculino , Metaloendopeptidasas/metabolismo , Mutación Missense , LinajeRESUMEN
Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal recessive disorder which leads to accumulation of poorly soluble 2,8-dihydroxyadenine in kidneys resulting in nephrolithiasis as well as chronic kidney disease from crystal nephropathy. This report describes a 55-year-old previously fit man who presented with shortness of breath and the investigative pathway that eventually led to a diagnosis of APRT deficiency. Early diagnosis has aided in timely institution of allopurinol, thereby improving his renal function and possibility of weaning off renal replacement therapy. Genetic testing has enabled early identification of other family members at risk and prevention of renal failure by commencing xanthine oxidoreductase (XOR) inhibitors. The issues surrounding kidney donation by a member of this family are also discussed. This case represents the importance of awareness and recognition of the signs and symptoms of this rare condition, complications of which can be easily prevented by early institution of XOR inhibitor therapy.
Asunto(s)
Adenina Fosforribosiltransferasa/deficiencia , Errores Innatos del Metabolismo/diagnóstico , Urolitiasis/diagnóstico , Adenina Fosforribosiltransferasa/genética , Alopurinol/uso terapéutico , Diagnóstico Precoz , Inhibidores Enzimáticos/uso terapéutico , Humanos , Masculino , Errores Innatos del Metabolismo/tratamiento farmacológico , Errores Innatos del Metabolismo/genética , Persona de Mediana Edad , Linaje , Urolitiasis/tratamiento farmacológico , Urolitiasis/genéticaRESUMEN
We present a case of monocytopaenia and mycobacteria-related infection (MonoMac) syndrome in a 30-year-old man of Indian origin. The clinical diagnosis of GATA2 haploinsufficiency was suspected after an unusual neurological presentation on a background of myelodysplastic syndrome and childhood pulmonary tuberculosis. The patient had a longitudinally extensive spinal cord lesion and a lesion in the medulla. No obvious infective cause for the spinal cord MRI abnormality was found, and the lesions were presumed to be inflammatory in nature. The family history consisted of autosomal dominant clinical features suggestive of GATA2 haploinsufficiency. Genetic testing in peripheral leucocytes revealed a pathogenic mutation in GATA2 This is the first-ever published case of possible MonoMac syndrome with a neurological presentation. The case highlights the rarity and complexity of the diagnosis and the clinical sequelae that ensued with the patient dying of gram-negative septicaemia while receiving intravenous steroid therapy for the spinal cord lesion.