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Fructose-1,6-bisphosphatase (FBPase) deficiency is a rare inborn error of fructose metabolism caused by pathogenic variants in the FBP1 gene. As gluconeogenesis is affected, catabolic episodes can induce ketotic hypoglycemia in patients. FBP1 analysis is the most commonly used approach for the diagnosis of this disorder. Herein, a Brazilian patient is reported. The proband, a girl born to a consanguineous couple, presented with severe hypoglycemia crisis in the neonatal period. At the age 17 months, presented a new crisis accompanied by metabolic acidosis associated with a feverish episode. Genetic analysis was performed by next-generation sequencing (NGS), identifying the NM_000507.3:c.611_614del variant in homozygosis in the FBP1 gene. In silico analysis and 3D modeling were performed, suggesting that this variant is associated with a loss of sites for substrate and Mg2+ binding and for posttranslational modifications of FBPase. The c.611_614del variant is located in a repetitive region of the FBP1 gene that appears to be a hotspot for mutational events. This frameshift creates a premature termination codon in the last coding exon which escapes the nonsense-mediated decay mechanism, according to in silico analysis. This variant results in an intrinsically disordered protein with loss of substrate recognition and post-translational modification sites.

Lysosomal storage disorders (LSDs) constitute a heterogeneous group of approximately 50 genetic disorders. LSDs diagnosis is challenging due to variability in phenotype penetrance, similar clinical manifestations, and a high allelic heterogeneity. A powerful tool for the diagnosis of the disease could reduce the “diagnostic odyssey” for affected families, leading to an appropriate genetic counseling and a better outcome for current therapies, since enzyme replacement therapies have been approved in Brazil for Gaucher, Fabry, and Pompe diseases, and are under development for Niemann-Pick Type B. However, application of next-generation sequencing (NGS) technology in the clinical diagnostic setting requires a previous validation phase. Here, we assessed the application of this technology as a fast, accurate, and cost-effective method to determine genetic diagnosis in selected LSDs. We have designed two panels for testing simultaneously 11 genes known to harbor casual mutations of LSDs. A cohort of 58 patients was used to validate those two panels, and the clinical utility of these gene panels was tested in four novel cases. We report the assessment of a NGS approach as a new tool in the diagnosis of LSDs in our service.

Lysosomal diseases (LDs), also known as lysosomal storage diseases (LSDs), are a heterogeneous group of conditions caused by defects in lysosomal function. LDs may result from deficiency of lysosomal hydrolases, membrane-associated transporters or other non-enzymatic proteins. Interest in the LD field is growing each year, as more conditions are, or will soon be treatable. In this article, we review the diagnosis of LDs, from clinical suspicion and screening tests to the identification of enzyme or protein deficiencies and molecular genetic diagnosis. We also cover the treatment approaches that are currently available or in development, including hematopoietic stem cell transplantation, enzyme replacement therapy, small molecules, and gene therapy.

Brazil is a country of continental dimensions and most genetic services are concentrated in the Southeast and South, including the Medical Genetics Service of the Hospital de Clínicas de Porto Alegre (MGS/HCPA). As many areas on the country do not have adequate medical genetics support, networks were designed to extend the service of the MGS/HCPA reference center. This paper presents the information and diagnosis networks that have their headquarters at MGS/HCPA: SIAT (National Information System on Teratogenic Agents), SIEM (Information Service on Inborn Errors of Metabolism), Alô Genética (Hello Genetics - Medical Genetics Information Service for Primary Health Care Professionals); Rede MPS Brasil (MPS-Mucopolysaccharidosis Brazil Network); Rede EIM Brasil (IEM-Inborn Errors of Metabolism Brazil Network), Rede NPC Brasil (Niemann-Pick C - NPC Brazil Network), Rede DLD Brasil (LSD-Lysosomal Storage Disorders Brazil Network), Rede DXB (MSUD-Maple Syrup Urine Disease Network), RedeBRIM (Brazilian Network of Reference and Information in Microdeletion Syndromes Project), Rede Neurogenética (Neurogenetics Network), and Rede Brasileira de Câncer Hereditário (Brazilian Hereditary Cancer Network). These tools are very useful to provide access to a qualified information and/or diagnostic service for specialized and non-specialized health services, bypassing difficulties that preclude patients to access reference centers.

We studied a family presenting 10 individuals affected by autosomal dominant deafness in all frequencies and three individuals affected by high frequency hearing loss. Genomic scanning using the 50k Affymetrix microarray technology yielded a Lod Score of 2.1 in chromosome 14 and a Lod Score of 1.9 in chromosome 22. Mapping refinement using microsatellites placed the chromosome 14 candidate region between markers D14S288 and D14S276 (8.85 cM) and the chromosome 22 near marker D22S283. Exome sequencing identified two candidate variants to explain hearing loss in chromosome 14 [PTGDR - c.G894A:p.R298R and PTGER2 - c.T247G:p.C83G], and one in chromosome 22 [MYH9, c.G2114A:p.R705H]. Pedigree segregation analysis allowed exclusion of the PTGDR and PTGER2 variants as the cause of deafness. However, the MYH9 variant segregated with the phenotype in all affected members, except the three individuals with different phenotype. This gene has been previously described as mutated in autosomal dominant hereditary hearing loss and corresponds to DFNA17. The mutation identified in our study is the same described in the prior report. Thus, although linkage studies suggested a candidate gene in chromosome 14, we concluded that the mutation in chromosome 22 better explains the hearing loss phenotype in the Brazilian family.

A adrenoleucodistrofia ligada ao X (X-ALD) é uma desordem hereditária do metabolismo peroxissomal, bioquimicamente caracterizada pelo acúmulo de ácidos graxos de cadeia muito longa (‘very long chain fatty acids”- VLCFA) em diferentes tecidos e em fluidos biológicos, sendo os principais ácidos acumulados o hexacosanóico (C26:0) e o tetracosanóico (C24:0). O acúmulo destes ácidos graxos está associado com desmielinização cerebral e insuficiência adrenal. A incidência desta condição é estimada em 1 para 25.000 em homens. Pelo menos seis fenótipos podem ser distinguidos, sendo a adrenoleucodistrofia (ALD) cerebral infantil e a adrenomieloneuropatia (AMN) os mais comuns. O tratamento preconizado consiste na utilização da mistura gliceroltrioleato/ gliceroltrierucato (GTO/GTE), conhecida como Óleo de Lorenzo, combinada com dieta pobre em VLCFA. Existem ainda, terapias alternativas como transplante de medula óssea e imunossupressão, além da utilização de lovastatina e fenilacetato de sódio. Neste trabalho fez-se uma avaliação do tratamento com Óleo de Lorenzo associado à dieta restrita em VLCFA de 7 pacientes homens com X-ALD analisando a evolução clínica e bioquímica. Os pacientes apresentaram uma redução média de 50% nos valores de C26:0 e de 42,8% na razão C26:0/C22:0 após o início do tratamento. A maioria dos pacientes permaneceu clinicamente bem e aproximadamente 30% dos pacientes apresentaram uma progressão rápida no curso clínico da doença. Parece não haver uma clara correlação bioquímico-clínica do tratamento. Os resultados nos mostram que novas terapias mais eficazes para X-ALD são necessárias para que se possa obter um melhor prognóstico da doença com progressão mais lenta dos sintomas apresentados ou mesmo reversão dos sintomas já presentes nos pacientes. X-Linked adrenoleukodystrophy (X-ALD) is a hereditary disorder of the peroxisomal metabolism biochemically characterized by the accumulation of very long chain fatty acids (VLCFA) in tissues and biological fluids. The major accumulated acids are hexacosanoic acid (C26:0) and tetracosanoic acid (C24:0). The disorder is characterized clinically by central and peripheral demyelination and adrenal insufficiency closely related to the accumulation of fatty acids. The incidence of X-ALD is estimated to be 1:25,000 males. At least six phenotypes can be distinguished. The most common phenotypes are childhood cerebral ALD and adrenomyeloneuropathy (AMN). The recommended therapy consists of the use of the glyceroltrioleate/glyceroltrierucate (GTO/GTE) mixture, known as Lorenzo’s Oil, combined with a VLCFA-poor diet. There are alternative treatments such as bone marrow transplantation and immunosuppression, as well as the use of lovastatin and sodium phenylacetate. In the present study we report the clinical and biochemical course of 7 male patients with X-ALD treated with Lorenzo’s Oil and a VLCFA-restricted diet. Treatment produced 50% reduction in C26:0 and 42.8% reduction in the C26:0/ C22:0 ratio. Most patients remained clinically well, although approximately 30% of them presented a rapid clinical deterioration. The results showed a poor biochemical-clinical correlation for treatment, indicating that new therapies for X-ALD are needed in order to obtain a better prognosis for patients.