RESUMEN
Developmental and epileptic encephalopathies (DEEs) are a heterogeneous group of epilepsies characterized by early-onset, refractory seizures associated with developmental regression or impairment, with a heterogeneous genetic landscape including genes implicated in various pathways and mechanisms. We retrospectively studied the clinical and genetic data of patients with genetic DEE who presented at two tertiary centers in Egypt over a 10-year period. Exome sequencing was used for genetic testing. We report 74 patients from 63 unrelated Egyptian families, with a high rate of consanguinity (58%). The most common seizure type was generalized tonic-clonic (58%) and multiple seizure types were common (55%). The most common epilepsy syndrome was early infantile DEE (50%). All patients showed variable degrees of developmental impairment. Microcephaly, hypotonia, ophthalmological involvement and neuroimaging abnormalities were common. Eighteen novel variants were identified and the phenotypes of five DEE genes were expanded with novel phenotype-genotype associations. Obtaining a genetic diagnosis had implications on epilepsy management in 17 patients with variants in 12 genes. In this study, we expand the phenotype and genotype spectrum of DEE in a large single ethnic cohort of patients. Reaching a genetic diagnosis guided precision management of epilepsy in a significant proportion of patients.
Asunto(s)
Epilepsia Generalizada , Epilepsia , Niño , Humanos , Egipto/epidemiología , Estudios Retrospectivos , Epilepsia/diagnóstico , Convulsiones/genética , Convulsiones/complicaciones , FenotipoRESUMEN
Hereditary spastic paraplegias (HSP) are rare, inherited neurodegenerative or neurodevelopmental disorders that mainly present with lower limb spasticity and muscle weakness due to motor neuron dysfunction. Whole genome sequencing identified bi-allelic truncating variants in AMFR, encoding a RING-H2 finger E3 ubiquitin ligase anchored at the membrane of the endoplasmic reticulum (ER), in two previously genetically unexplained HSP-affected siblings. Subsequently, international collaboration recognized additional HSP-affected individuals with similar bi-allelic truncating AMFR variants, resulting in a cohort of 20 individuals from 8 unrelated, consanguineous families. Variants segregated with a phenotype of mainly pure but also complex HSP consisting of global developmental delay, mild intellectual disability, motor dysfunction, and progressive spasticity. Patient-derived fibroblasts, neural stem cells (NSCs), and in vivo zebrafish modeling were used to investigate pathomechanisms, including initial preclinical therapy assessment. The absence of AMFR disturbs lipid homeostasis, causing lipid droplet accumulation in NSCs and patient-derived fibroblasts which is rescued upon AMFR re-expression. Electron microscopy indicates ER morphology alterations in the absence of AMFR. Similar findings are seen in amfra-/- zebrafish larvae, in addition to altered touch-evoked escape response and defects in motor neuron branching, phenocopying the HSP observed in patients. Interestingly, administration of FDA-approved statins improves touch-evoked escape response and motor neuron branching defects in amfra-/- zebrafish larvae, suggesting potential therapeutic implications. Our genetic and functional studies identify bi-allelic truncating variants in AMFR as a cause of a novel autosomal recessive HSP by altering lipid metabolism, which may potentially be therapeutically modulated using precision medicine with statins.
Asunto(s)
Inhibidores de Hidroximetilglutaril-CoA Reductasas , Paraplejía Espástica Hereditaria , Animales , Humanos , Paraplejía Espástica Hereditaria/tratamiento farmacológico , Paraplejía Espástica Hereditaria/genética , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Pez Cebra , Mutación , Neuronas Motoras , Receptores del Factor Autocrino de Motilidad/genéticaRESUMEN
Fumaric aciduria resulting from fumarate hydratase deficiency is a rare inherited disorder of the Krebs tricarboxylic acid cycle that is characterized by neurologic manifestations, a spectrum of brain abnormalities, and the excretion of fumaric acid in urine. We describe a 3 year old Sri Lankan boy who was referred at age 10 months with poor weight gain and hypotonia for further laboratory investigations. In addition to global developmental delay, there were noticeable dysmorphic features with a prominent forehead, low-set ears, micrognathia, and hypertelorism with persistent neutropenia. Urine organic acid assay revealed a massive elevation of fumaric acid on 2 occasions. Molecular analysis revealed a homozygous likely pathogenic missense variant, NM000143.3:c.1048C>T p. (Arg350Trp), in the FH gene, confirming the biochemical diagnosis. Our patient was the first patient in Sri Lanka molecularly diagnosed with fumaric aciduria. This case study highlights the importance of performing organic acid assays in children presenting with neurologic manifestations especially when these are suspected to have a metabolic basis.
Asunto(s)
Pruebas Diagnósticas de Rutina , Hipotonía Muscular , Niño , Preescolar , Fumarato Hidratasa/deficiencia , Fumarato Hidratasa/genética , Fumarato Hidratasa/metabolismo , Humanos , Lactante , Masculino , Errores Innatos del Metabolismo , Hipotonía Muscular/diagnóstico , Hipotonía Muscular/genética , Trastornos Psicomotores , Sri LankaRESUMEN
Biallelic changes in the ZNFX1 gene have been recently reported to cause severe familial immunodeficiency. Through a search of our bio/databank with information from genetic testing of >55 000 individuals, we identified nine additional patients from seven families with six novel homozygous ZNFX1 variants. Consistent with the previously described phenotype, our patients suffered from monocytosis, thrombocytopenia, hepatosplenomegaly, recurrent infections, and lymphadenopathy. The two most severely affected probands also had renal involvement and clinical presentations compatible with hemophagocytic lymphohistiocytosis. The disease was less lethal among our patients than previously reported. We identified two missense changes, two variants predicted to result in complete protein loss through nonsense-mediated decay, and two frameshift changes that likely introduce a truncation. Our findings (i) independently confirm the role of ZNFX1 in primary genetic immunodeficiency, (ii) expand the genetic and clinical spectrum of ZNFX1-related disease, and (iii) illustrate the utility of large, well-curated, and continually updated genotype-phenotype databases in resolving molecular diagnoses of patients with initially negative genetic testing findings.
Asunto(s)
Alelos , Antígenos de Neoplasias/genética , Enfermedades Hematológicas/diagnóstico , Enfermedades Hematológicas/genética , Mutación , Enfermedades de Inmunodeficiencia Primaria/diagnóstico , Enfermedades de Inmunodeficiencia Primaria/genética , Mapeo Cromosómico , Biología Computacional/métodos , Análisis Mutacional de ADN , Bases de Datos Genéticas , Facies , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Homocigoto , Humanos , Linaje , FenotipoAsunto(s)
Proteínas de Anclaje a la Quinasa A/genética , Proteínas del Citoesqueleto/genética , Regulación de la Expresión Génica , Síndrome de QT Prolongado/genética , Metoprolol/uso terapéutico , Torsades de Pointes/diagnóstico por imagen , Anciano de 80 o más Años , Ecocardiografía Doppler/métodos , Electrocardiografía/métodos , Servicio de Urgencia en Hospital , Estudios de Seguimiento , Hematoma Subdural/diagnóstico , Hematoma Subdural/etiología , Humanos , Síndrome de QT Prolongado/complicaciones , Síndrome de QT Prolongado/diagnóstico por imagen , Síndrome de QT Prolongado/tratamiento farmacológico , Masculino , Multimorbilidad , Mutación/genética , Síncope/diagnóstico , Síncope/etiología , Torsades de Pointes/complicaciones , Torsades de Pointes/tratamiento farmacológico , Resultado del TratamientoRESUMEN
Hyperphenylalaninemias (HPAs) are genetic diseases predominantly caused by a wide range of variants in the phenylalanine hydroxylase (PAH) gene. In vitro expression analysis of PAH variants offers the opportunity to elucidate the molecular mechanisms involved in HPAs and to clarify whether a disease-associated variant is genuinely pathogenic, while investigating the severity of a metabolic phenotype, and determining how a variant exerts its deleterious effects on the PAH enzyme. To study the effects of gene variants on PAH activity, we investigated eight variants: c.611A>G (p.Y204C), c.635T>C (p.L212P), c.746T>C (p.L249P), c.745C>T (p.L249F), c.809G>A (p.R270K), c.782G>C (p.R261P), c.587C>A (p.S196Y) and c.1139C>T (p.T380M), associated with different phenotypic groups. Transient expression of mutant full-length cDNAs in COS-7 cells yielded PAH proteins with PAH activity levels between 7% and 51% compared to the wild-type enzyme. With one exception (p.Y204C, which had no significant impact on PAH function), lower PAH activity was associated with a more severe phenotype (e.g. p.L249P with 7% PAH activity, 100% of classic PKU and no BH4 responsiveness), while higher activity correlated with milder phenotypes (e.g. p.T380M with 28% PAH activity, 97% of mild HPA and 83% of BH4 responsiveness). The results of the in vitro residual PAH activity have major implications, both for our understanding of genotype-phenotype correlations, and thereby existing inconsistencies, but also for the elucidation of the molecular basis of tetrahydrobiopterin (BH4) responsiveness.
Asunto(s)
Mutación Missense , Fenilalanina Hidroxilasa , Fenilcetonurias , Sustitución de Aminoácidos , Animales , Biopterinas/análogos & derivados , Biopterinas/genética , Biopterinas/metabolismo , Células COS , Chlorocebus aethiops , Humanos , Fenilalanina Hidroxilasa/genética , Fenilalanina Hidroxilasa/metabolismo , Fenilcetonurias/enzimología , Fenilcetonurias/genéticaRESUMEN
Small supernumerary marker chromosomes (sSMCs) originating from chromosome 10 are rare. A limited number of cases are documented. We report a new diagnosis of a mosaic sSMC (10) in a normal female who asked for genetic evaluation before undergoing controlled ovarian hyperstimulation, in vitro fertilization, and embryo transfer. Chromosome preparations from peripheral lymphocyte cultures were performed according to standard procedures. QFQ-banded chromosomes confirmed the presence of an sSMC: 47,XX,+mar[49]/46,XX[51]. FISH and array CGH analysis showed that the sSMC consisted of chromosome 10 with a gain of the 10p11.1p11.21 (2.5 Mb) chromosomal region. The presence of sSMC (10) was also confirmed in the patient's mother and sister. It did not appear to affect the phenotype of the women who were phenotypically normal and healthy, and at the time of writing the woman became pregnant naturally. Phenotypes associated with an sSMC vary from normal to severely abnormal. It has been shown that variations in the chromosomal region of sSMCs result in observable differences in clinical outcome. The phenotypical consequences of sSMCs are difficult to predict because of differences in euchromatic DNA content, chromosomal origin, and varying degrees of mosaicism. Therefore, the continued investigation of a larger number of sSMC cases, in particular those originating from chromosome 10 that are the infrequently encountered and characterized, and a better understanding of the genetic content is important in order to improve the delineation of karyotype-phenotype correlation, contributing to a more informed prenatal counseling or prognosis.
Asunto(s)
Aberraciones Cromosómicas , Cromosomas Humanos Par 10 , Adulto , Femenino , Humanos , FenotipoRESUMEN
We investigated the mutation spectrum of the phenylalanine hydroxylase gene (PAH) in a cohort of patients from 33 Italian PKU families. Mutational screening of the known coding region, including conventional intron splice sites, was performed by direct sequencing of the patients' genomic DNA. Thirty-three different disease causing mutations were identified in our patient group, including 19 missense, 6 splicing, 3 nonsense, 5 deletions, with a detection rate of 100%. The most prevalent mutation was the IVS10-11G>A, accounting for 12.1% of PKU alleles studied. Other frequent mutations were: p.R261Q (9.1%), p.P281L (7.6%), and p.R408W (6.1%). We also identified one novel missense mutation, p.H290Q. A spectrum of 31 different genotypes was observed and a genotype based predictions of BH4-responsiveness were assessed. Among all genotypes, 13 were predicted to be BH4-responsive represented by thirteen PKU families. In addition, genotype-phenotype correlations were performed. This study reveals the importance of a full genotyping of PKU patients and the prediction of BH4-responsiveness, not only because of the definitive diagnosis and prediction of the optimal diet, but also to point out those patients that could benefit from new therapeutic approach. They may potentially benefit from BH4 therapy which, combined with a less strict diet, or eventually in special cases as monotherapy, may contribute to reduce nutritional deficiencies and minimize neurological and psychological dysfunctions.
Asunto(s)
Alelos , Biopterinas/análogos & derivados , Fenilcetonurias/tratamiento farmacológico , Fenilcetonurias/genética , Adolescente , Adulto , Biopterinas/farmacología , Biopterinas/uso terapéutico , Niño , Preescolar , ADN/genética , Dieta , Estudios de Asociación Genética , Genotipo , Humanos , Lactante , Italia , Mutación , Fenotipo , Fenilalanina/sangre , Fenilcetonurias/dietoterapia , Pronóstico , Resultado del Tratamiento , Adulto JovenAsunto(s)
Factor VIII/genética , Hemofilia A/genética , Proteínas Mutantes/genética , Mutación , Codón sin Sentido , Estudios de Cohortes , Análisis Mutacional de ADN , Factor VIII/química , Hemofilia A/sangre , Humanos , Mutación INDEL , Italia , Masculino , Proteínas Mutantes/química , Mutación Missense , Eliminación de Secuencia , Inversión de SecuenciaRESUMEN
Classical phenylketonuria (PKU) and mild hyperphenylalaninemia (MHP) are two phenotypes of phenylalanine hydroxylase (PAH) deficiency with different degrees of severity. We have analyzed three families in which classical PKU, MHP and a normal phenotype occurred within each family due to the different combinations of three mutations segregating within the family. Indeed, sequence PAH analysis revealed three different alleles segregating in each family. This report suggests that when discordant phenotypes occur in a family, complete analysis of the PAH gene may be performed in order to support the diagnosis and assist in accurate genetic counseling and patient management. We further support the marked heterogeneity of hyperphenylalaninemia primarily due to allelic heterogeneity at the PAH locus.
Asunto(s)
Familia , Linaje , Fenotipo , Fenilalanina Hidroxilasa/genética , Fenilcetonurias/genética , Adulto , Análisis Mutacional de ADN , Femenino , Asesoramiento Genético , Humanos , MasculinoRESUMEN
BACKGROUND: Mutations in the gene encoding phenylalanine hydroxylase (PAH, EC 1.14.16.1) are associated with various degrees of hyperphenylalaninemia (HPA), including classical phenylketonuria (PKU). OBJECTIVE: The aim of the study was to determine the mutations responsible for mild forms of HPA and to relate different clinical phenotypes of HPA patients to their PAH genotypes in order to better predict the clinical phenotype and implement optimal dietary therapy and prognosis in newborns with the disease. METHODS: Phenylalanine hydroxylase (PAH) gene mutations have been analyzed by direct DNA sequencing in 30 HPA patients (Phe levels ranging from 2 to 6mg/dL) from Southern Italy who were identified in a neonatal screening program and a genotype-phenotype correlation was performed. RESULTS: PAH gene mutation was identified in 39 out of 60 alleles with a mutation detection rate of 65%. Eighteen mutations, 2 undescribed, were observed (13 missense mutations, 1 deletion, 4 splice site mutations). Using the "in vitro" predicted residual activity, a good genotype-phenotype correlation was obtained also in a new mild HPA case, a PAH compound heterozygote, previously undetected. CONCLUSION: A marked genetic heterogeneity was found in HPA patients from Southern Italy and a good genotype-phenotype correlation was obtained. Identification of PAH gene mutations responsible for PAH deficiency will therefore be useful in the prediction of biochemical and clinical phenotypes in HPA patients.