Molecular Genetics of Niemann-Pick Type C Disease in Italy: An Update on 105 Patients and Description of 18 NPC1 Novel Variants.

Niemann-Pick type C (NPC) disease is an autosomal recessive lysosomal storage disorder caused by mutations in NPC1 or NPC2 genes. In 2009, the molecular characterization of 44 NPC Italian patients has been published. Here, we present an update of the genetic findings in 105 Italian NPC patients belonging to 83 unrelated families (77 NPC1 and 6 NPC2). NPC1 and NPC2 genes were studied following an algorithm recently published. Eighty-four different NPC1 and five NPC2 alleles were identified. Only two NPC1 alleles remained non detected. Sixty-two percent of NPC1 alleles were due to missense variants. The most frequent NPC1 mutation was the p.F284Lfs*26 (5.8% of the alleles). All NPC2 mutations were found in the homozygous state, and all but one was severe. Among newly diagnosed patients, 18 novel NPC1 mutations were identified. The pathogenic nature of 7/9 missense alleles and 3/4 intronic variants was confirmed by filipin staining and NPC1 protein analysis or mRNA expression in patient's fibroblasts. Taken together, our previous published data and new results provide an overall picture of the molecular characteristics of NPC patients diagnosed so far in Italy.

Comprehensive Evaluation of Plasma 7-Ketocholesterol and Cholestan-3ß,5α,6ß-Triol in an Italian Cohort of Patients Affected by Niemann-Pick Disease due to NPC1 and SMPD1 Mutations.

Niemann-Pick C disease (NPCD) is a rare autosomal recessive neurovisceral disorder with a heterogeneous clinical presentation. Cholestan-3ß,5α,6ß-triol and 7-ketocholesterol have been proposed as biomarkers for the screening of NPCD. In this work, we assessed oxysterols levels in a cohort of Italian patients affected by NPCD and analyzed the obtained results in the context of the clinical, biochemical and molecular data. In addition, a group of patients affected by Niemann-Pick B disease (NPBD) were also analyzed. NPC patients presented levels of both oxysterols way above the cut off value, except for 5 siblings presenting the variant biochemical phenotype who displayed levels of 3ß,5α,6ß-triol below or just above the cut-off value; 2 of them presented also normal levels of 7-KC. Both oxysterols were extremely high in a patient presenting the neonatal systemic lethal phenotype. All NPB patients showed increased oxysterols levels. In conclusion, the reported LC-MS/MS assay provides a robust non-invasive screening tool for NPCD. However, false negative results can be obtained in patients expressing the variant biochemical phenotype. These data strengthen the concept that the results should always be interpreted in the context of the patients' clinical picture and filipin staining and/or genetic studies might still be undertaken in patients with normal levels of oxysterols if symptoms are highly suggestive of NPCD. Both oxysterols are significantly elevated in NPB patients; thus a differential diagnosis should always be performed in patients presenting isolated hepatosplenomegaly, a common clinical sign of both NPCD and NPBD.

Insulin sensitivity and early-phase insulin secretion in normoglycemic Huntington's disease patients.

BACKGROUND: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by an expanded CAG repeat in exon 1 of the HTT gene. There is increasing evidence pointing towards an involvement of the endocrine system in HD. Recent studies, investigating the increased risk of diabetes mellitus and impaired insulin sensitivity and secretion in HD patients, led to contradictory results. OBJECTIVE: To investigate glucose homeostasis in HD. METHODS: Twenty-eight consecutive patients with HD and 28 healthy controls were matched for age, sex, and BMI. Diagnosis of HD was confirmed genetically. Clinical tools for assessment were the Unified Huntington's Disease Rating Scale (UHDRS) motor section and the Total Function Capacity (TFC). Basal metabolic and endocrine investigations and a 2-hour 75-g oGTT were performed. We used the homeostasis model assessment of insulin resistance (HOMA-IR) as index of insulin sensitivity and the insulinogenic index to assess insulin secretion. RESULTS: HD patients did not differ from the controls with respect to fasting plasma glucose, insulin sensitivity and secretion. CAG expansion size, disease stage and duration, or BMI did not influence HOMA-IR and insulinogenic index. Patients showed lower serum glucose (-19%) and insulin levels (-48%) at 30 min and higher serum insulin levels at 90 (+132%) and 120 min (+380%). CONCLUSIONS: Our data do not support an increased risk of diabetes among HD patients although they show glucose regulation abnormalities with a flat glucose curve and delayed insulin peak after oral glucose load.

Pulse pressure and presence of coronary artery calcification.

BACKGROUND: Coronary calcification (CAC) is found in early stages of CKD. Pulse pressure (PP) predicts CAC in dialysis patients. This study evaluates the accuracy of PP in predicting CAC in patients not yet on dialysis (CKD patients). METHODS: CKD patients (n = 388) underwent coronary calcium score (CAC score) and abdominal x-ray (n = 128) for estimating aorta calcification (AAC). Biochemistry and PP were measured every 3 and 6 months in patients with stage 4 to 5 and 2 to 3 CKD, respectively. The accuracy of PP and AAC was assessed by receiver operating characteristics analysis. RESULTS: PP correlated with CAC score in the whole cohort and in patients with stages 2 to 3 and stages 4 to 5 CKD. PP >60 mmHg predicted CAC score >0 (OR: 2.14; P < 0.001), > or =100 (OR: 2.92; P < 0.001), > or =400 (OR: 6.17; P < 0.001) after multivariable adjustment. Area under the curve (AUC) was 0.626 for CAC score >0, 0.676 for score >100, and 0.746 for score >400. PP >60 mmHg reduced the rate of event-free survival. AAC was found in 58% of patients and correlated with CAC score. AUC was 0.628 for CAC score >0, 0.652 for score >100, 0.831 for score >400. CONCLUSION: PP may identify CKD patients with subclinical CAC who need further evaluation. Accuracy of PP and AAC is nearly similar in predicting CAC. High PP indicates vessel wall alterations leading to adverse outcome.