GM1 gangliosidosis and Morquio B disease: an update on genetic alterations and clinical findings.

GM1 gangliosidosis and Morquio B syndrome, both arising from beta-galactosidase (GLB1) deficiency, are very rare lysosomal storage diseases with an incidence of about 1:100,000-1:200,000 live births worldwide. Here we report the beta-galactosidase gene (GLB1) mutation analysis of 21 unrelated GM1 gangliosidosis patients, and of 4 Morquio B patients, of whom two are brothers. Clinical features of the patients were collected and compared with those in literature. In silico analyses were performed by standard alignments tools and by an improved version of GLB1 three-dimensional models. The analysed cohort includes remarkable cases. One patient with GM1 gangliosidosis had a triple X syndrome. One patient with juvenile GM1 gangliosidosis was homozygous for a mutation previously identified in Morquio type B. A patient with infantile GM1 gangliosidosis carried a complex GLB1 allele harbouring two genetic variants leading to p.R68W and p.R109W amino acid changes, in trans with the known p.R148C mutation. Molecular analysis showed 27 mutations, 9 of which are new: 5 missense, 3 microdeletions and a nonsense mutation. We also identified four new genetic variants with a predicted polymorphic nature that was further investigated by in silico analyses. Three-dimensional structural analysis of GLB1 homology models including the new missense mutations and the p.R68W and p.R109W amino acid changes showed that all the amino acid replacements affected the resulting protein structures in different ways, from changes in polarity to folding alterations. Genetic and clinical associations led us to undertake a critical review of the classifications of late-onset GM1 gangliosidosis and Morquio B disease.

Newborn Screening for Tyrosinemia Type I: Further Evidence that Succinylacetone Determination on Blood Spot Is Essential.

Tyrosinemia type I is a genetic disorder characterized by accumulation in the blood and urine of the toxic metabolite succinylacetone (SUAC), not detectable in healthy samples. In many countries, newborns are screened for tyrosinemia type I using tyrosine as a primary marker. Unfortunately, tyrosine accumulation may take longer to occur and it may be not obvious when specimens are collected, in the first few days of life, as for newborn screening. In 2008, we reported changes to simultaneously measure acylcarnitines, amino acids, and SUAC during expanded newborn screening. We established the usefulness of this method after identifying a first asymptomatic newborn affected by tyrosinemia type I. Now we report a second infant with positive SUAC screening result (14.1 µmol/L, n.v. < 2) and normal tyrosine concentration (74 µmol/L; n.v. < 250). We also performed molecular analysis of FAH gene in both patients after diagnosis at newborn screening. They had consanguineous parents and were both homozygous for two known disease-causing mutations of the FAH gene. The outcome of patients detected in the MS/MS screening is significantly favorable. We also report our results of newborn screening for tyrosinemia type I before and after inclusion of SUAC as a primary marker for this disease.

Effects of atorvastatin and rosuvastatin on thromboxane-dependent platelet activation and oxidative stress in hypercholesterolemia.

OBJECTIVES: We examined the time-dependent effects of atorvastatin and rosuvastatin on in vivo oxidative stress and platelet activation, to assess whether these phenomena are related to any pleiotropic effect of any statin or to their LDL-lowering effect. We also asked whether the presence of specific allele frequencies in carriers of the 3'UTR/lectin-like oxidized LDL receptor-1 (LOX-1) polymorphism may influence the effect of either statin. METHODS: We included 60 hypercholesterolemic subjects, previously screened for LOX-1 3'UTR polymorphism, randomized, according to genetic profile (15 T and 15 C carriers for each arm), to atorvastatin 20mg/day or rosuvastatin 10mg/day. RESULTS: After 8 weeks, atorvastatin and rosuvastatin were associated with comparable, significant reductions in LDL cholesterol (40.8% and 43.6%, respectively), plasma hs-CRP (9.5% vs. 13.8%), urinary 11-dehydro-thromboxane (TX) B(2) (38.9% vs. 27.1%) and 8-iso-prostaglandin (PG) F(2α) (39.4% vs. 19.4%). The impact of rosuvastatin or atorvastatin on CRP, 8-iso-PGF(2α), and 11-dehydro-TXB(2) did not differ according to the LOX-1 haplotype. On multiple regression analyses, only CRP and LDL were independent predictors of 11-dehydro-TXB(2), and only LDL was a significant predictor of 8-iso-PGF(2α). CONCLUSIONS: Both atorvastatin and rosuvastatin cause comparable reductions of thromboxane-dependent platelet activation, lipid peroxidation and inflammation. The presence of 3'UTR/LOX-1 polymorphism does not affect the changes induced by either statin.

3'UTR/T polymorphism of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is associated with modified anti-platelet activity of atorvastatin in hypercholesterolemic subjects.

Oxidized-low density lipoproteins (ox-LDL) and the specific receptor LOX-1 are involved in atherogenesis and atherothrombosis. LOX-1 downregulation is associated with the anti-platelet action of atorvastatin. 3'UTR/T LOX-1 polymorphism has been associated with increased risk of coronary artery disease. This study was planned to determine whether LOX-1 genetic variations could affect anti-platelet action of atorvastatin. We studied by platelet P-selectin (P-sel), CD36 and LOX-1 expression (cytofluorimetric detection) whether differences in cellular activation could be suitable in 109 3'UTR/T carriers out of 201 hypercholesterolemic subjects treated with atorvastatin 20mg/day. Hyperactivated platelets (P-sel in resting cells and % variation upon thrombin activation, p<0.001) were detected at baseline in patients without significant differences between T or C carriers. P-sel and platelet-associated ox-LDL, were significantly decreased (all p<0.001) in C carriers after one week of treatment before LDL reduction. In 3'UTR/T carriers P-sel was reduced (p<0.01) after 6 weeks of treatment according to LDL and ox-LDL reduction. In 3'UTR/T carriers atorvastatin reduced platelet activity by LDL and ox-LDL lowering and not by rapid CD36 and LOX-1 downregulation as in C carriers. Such data suggest that in T carriers LDL lowering is needed to achieve anti-platelet action.