Browsing by Author "Dias, Aureliano"
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- Arylsulfatase B mutations in Portuguese MPS VI patientsPublication . Amaral, Olga; Dias, Aureliano; Pinto, Eugénia; Ribeiro, Isaura; Sá Miranda, M.C.Mucopolysaccharidosis type VI (MPS VI, OMIM 253200) is a rare autosomal recessive disorder characterized by the deficient activity of arylsulfatase B (ARSB, EC 3.1.6.12). In Portugal, the birth prevalence of the rare MPS VI is 0.42/100000. With the emerging availability of promising enzyme replacement therapy for this disease, mutation analysis becomes an important tool not only for the genetic counselling of individuals at risk, but also in the prognosis of the disease and identification of cases which might benefit of an early therapeutic intervention. In this work we present the preliminary results obtained through mutation analysis of 12 Portuguese patients. This study involved PCR amplification and direct automated sequencing analysis of exons and intron boundaries. The identification of seven mutations is reported: two recently described deletions, three missense mutations (two of them new), one novel nonsense mutation and also one new splicing mutation. Additionally, two previously described point mutations were detected in the form of a complex allele. Seven patients were homozygous for various mutations, while the remaining five were compound heterozygotes. Interestingly, three mutations seem to have an increased frequency in the Portuguese sample studied jointly c.1533del23 (Petry et al.,2003), c.427delG (Karageorgos et al.,2004) and R315Q (Villani et al.,1999) represent 58% of the patients alleles. In some of the cases Western blot analysis was also carried out. The impact of the various mutations at the protein level and the resulting phenotypic implications are discussed.
- Iron-sulfur Cluster ISD11 Deficiency (LYRM4 Gene) Presenting as Cardiorespiratory Arrest and 3-methylglutaconic AciduriaPublication . Coelho, Margarida Paiva; Correia, Joana; Dias, Aureliano; Nogueira, Célia; Bandeira, Anabela; Martins, Esmeralda; Vilarinho, LauraIn the era of genomics, the number of genes linked to mitochondrial disease has been quickly growing, producing massive knowledge on mitochondrial biochemistry. LYRM4 gene codifies for ISD11, a small protein (11 kDa) acting as an iron-sulfur cluster, that has been recently confirmed as a disease-causing gene for mitochondrial disorders. We present a 4-year-old girl patient, born from non-consanguineous healthy parents, with two episodes of cardiorespiratory arrest after respiratory viral illness with progressive decreased activity and lethargy, at the age of 2 and 3 years. She was asymptomatic between crisis with regular growth and normal development. During acute events of illness, she had hyperlactacidemia (maximum lactate 5.2 mmol/L) and urinary excretion of ketone bodies and 3-methylglutaconic acid, which are normalized after recovery. A Next Generation Sequence approach with a broad gene panel designed for mitochondrial disorders revealed a novel probably pathogenic variant in homozygosity in the LYRM4 gene [p.Tyr31Cys (c.92A>G)] with Mendelian segregation. Functional studies in the skeletal muscle confirmed a combined deficiency of the mitochondrial respiratory chain (I, II, and IV complexes). To our knowledge, this is the third case of LYRM4 deficiency worldwide and the first with 3-methylglutaconic aciduria, not reported in any Fe-S cluster deficiency. Remarkably, it appears to be no neurological involvement so far, only with life-threating acute crisis triggered by expectably benign autolimited illnesses. Respiratory chain cofactors and chaperones are a new field of knowledge and can play a remarkable effect in system homeostasis.
- Primary hyperoxaluria Type 1: organic aciduria diagnosed in plasmaPublication . Valongo, Carla; Rodrigues, Marilia; Dias, Aureliano; Vilarinho, LauraBackground: Primary hyperoxaluria Type 1 (PH1) is a rare autosomal recessive inborn error of glyoxylate metabolism, caused by a deficiency of the liver-specific peroxisomal enzyme alanine:glyoxylate aminotransferase. The disorder results in overproduction and excessive urinary excretion of oxalate, causing recurrent urolithiasis and nephrocalcinosis. Patient and methods: The patient, a 38 year-old-woman, was referred to our lab with severe arthritis in the hips and knees, calcinosis and stage V chronic renal failure under hemodialysis. No urine samples were available to perform organic acids analysis so we studied patient plasma. Samples were extracted with ethylacetate and analyzed by GC-MS. Results: Plasmatic organic acids profile in two different samples revealed a marked excretion of oxalate (131 and 125 µmol/L; controls: 0-5) and glycolate (362 and 338 µmol/L; controls: 9-42). Glicerate concentration was normal (17 and 15 µmol/L; controls: 0-24). Conclusions: The usual biochemical indicator of PH1 is a persistently and markedly elevated urine oxalate. In the absence of urine samples, this biochemical diagnosis can also be done in plasma samples. PH1 is a treatable organic aciduria and an early and accurate diagnosis preserves renal function. So, it is important to screen for PH1 in patients with recurrent urolithiasis or unexplained renal insufficiency.
- Sitosterolémia: uma causa rara de hipercolesterolemiaPublication . Padeira, Gonçalo; Garcia, Ana Margarida; Conde, Marta; Carvalho, Rodrigo; João, Alexandre; Gomes, Inês; Correia, Carla; Valongo, Carla; Dias, Aureliano; Alves, Ana Catarina; Medeiros, Ana; Bourbon, Mafalda; Ferreira, Ana CristinaA Sitosterolémia (OMIM 210250) é uma doença autossómica recessiva rara causada por mutações nos genes ABCG5/ABCG8 que codificam o transportador intestinal e biliar dos esteróis vegetais, com consequente acumulação no sangue e tecidos. Caracteriza-se pela presença de xantomas e aterosclerose prematura. O diagnóstico é feito pela deteção de sitosterol, campesterol e stigmasterol no plasma e confirmado por estudo genético. Faz diagnóstico diferencial com a Hipercolesterolemia Familiar (FH). O tratamento inclui a restrição dietética de esteróis vegetais associado a inibidor da absorção intestinal de colesterol.