Simultaneous detection of the C282Y, H63D and S65C mutations in the hemochromatosis gene using quenched-FRET real-time PCR

Hereditary hemochromatosis (HH) is a common autosomal disorder of iron metabolism mainly affecting Caucasian populations. Three recurrent disease-associated mutations have been detected in the hemochromatosis gene (HFE): C282Y, H63D, and S65C. Although HH phenotype has been associated with all three mutations, C282Y is considered the most relevant mutation responsible for hemochromatosis. Clinical complications of HH include cirrhosis of the liver, congestive cardiac failure and cardiac arrhythmias, endocrine pancreatic disease, which can be prevented by early diagnosis and treatment. Therefore, a reliable genotyping method is required for presymptomatic diagnosis. We describe the simultaneous detection of the C282Y, H63D and S65C mutations in the hemochromatosis gene by real-time PCR followed by melting curve analysis using fluorescence resonance energy transfer (FRET) probes. The acceptor fluorophore may be replaced by a quencher, increasing multiplex possibilities. Real-time PCR results were compared to the results of sequencing and conventional PCR followed by restriction digestion and detection by agarose gel electrophoresis (PCR-RFLP). Genotypes from 80 individuals obtained both by the conventional PCR-RFLP method and quenched-FRET real-time PCR were in full agreement. Sequencing also confirmed the results obtained by the new method, which proved to be an accurate, rapid and cost-effective diagnostic assay. Our findings demonstrate the usefulness of real-time PCR for the simultaneous detection of mutations in the HFE gene, which allows a reduction of a significant amount of time in sample processing compared to the PCR-RFLP method, eliminates the use of toxic reagents, reduces the risk of contamination in the laboratory, and enables full process automation.

The Lebanese mutation as an important cause of familial hypercholesterolemia in Brazil

Familial hypercholesterolemia (FH) is a common autosomal disorder that affects about one in 500 individuals in most Western populations and is caused by a defect in the low-density-lipoprotein receptor (LDLr) gene. In this report we determined the molecular basis of FH in 59 patients from 31 unrelated Brazilian families. All patients were screened for the Lebanese mutation, gross abnormalities of the LDLr gene, and the point mutation in the codon 3500 of the apolipoprotein B-100 gene. None of the 59 patients presented the apoB-3500 mutation, suggesting that familial defective ApoB-100 (FDB) is not a major cause of inherited hypercholesterolemia in Brazil. A novel 4-kb deletion in the LDLr gene, spanning from intron 12 to intron 14, was characterized in one family. Both 5' and 3' breakpoint regions were located within Alu repetitive sequences, which are probably involved in the crossing over that generated this rearrangement. The Lebanese mutation was detected in 9 of the 31 families, always associated with Arab ancestry. Two different LDLr gene haplotypes were demonstrated in association with the Lebanese mutation. Our results suggest the importance of the Lebanese mutation as a cause of FH in Brazil and by analogy the same feature may be expected in other countries with a large Arab population, such as North American and Western European countries.

Anti-PGL1 levels in leprosy patients and their contacts

1. We determined the anti-PGL1 levels of 402 individuals from the Ribeir ao Preto region since the phenolic glycolipid (PGL1) is a specific Mycobacterium leprae antigen. This group consisted of 47 leprosy patients (26 with the lepromatous form, 16 with the tuberculoid form and 5 with the borderline form), 12 tuberculosis patients, 19 leprosy contacts, and 324 healthy blood donors from the Hemocenter of the University Hospital, Faculty of Medicine of Ribeir ao Preto, University of S ao Paulo. Anti-PGL1 levels were detected by ELISA. 2. Anti-PGL1 levels were normal in patients with tuberculoid and borderline leprosy, in tuberculosis patients and in almost all of the healthy blood donors. Patients with untreated lepromatous leprosy had elevated anti-PGL1 levels while most patients under treatment (9/16) had normal anti-PGL1 levels. Only 3 per cent of blood donors (10/324) had elevated anti-PGL1 levels, but when these individuals were submitted to clinical and bacilloscopic examination no signs of disease were found. To complete the clinical investigation, these 10 subjects were submitted to the Mitsuda reaction which was negative in 3 of them. All of these 10 subjects are being monitored, since they may be at risk to develop leprosy. 3. On the basis of the present data, it seems that ELISA is a potentially important assay for the detection and chemotherapy of subclinical leprosy, permitting the control of epidemic centers of the disease