Gene variants associated to malignant thyroid disease in familial adenomatous polyposis: a novel APC germline mutation.

BACKGROUND AND AIM: Familial adenomatous polyposis (FAP) is an autosomal inherited syndrome characterized by hundreds to thousands colorectal adenomatous polyps with oncological transformation lifetime risk of 100%. FAP is mainly associated with mutations in APC (autosomal dominant inheritance) or MUTYH (autosomal recessive inheritance) genes. Affected individuals are at increased risk of developing extra-intestinal tumors. Lifetime risk of developing thyroid carcinoma has been described in previous reports of about 2-12%, mainly in females, and the mean age is below 30 yr. About 95% of cancers are papillary thyroid carcinomas (PTC), mostly multifocal. The aim of this study was to evaluate the frequency of PTC among our series of FAP patients and to assess the type of gene mutation associated with the disease. METHODS: Fifty-four subjects from 36 FAP families were selected (29 females/25 males) and the mean age (±SD) at diagnosis was 28.8±10.8 yr. All patients underwent blood examination for thyroid hormones and antibodies, germline mutational analysis of APC and/or MUTYH genes, thyroid ultrasound, and endocrinological evaluation. RESULTS: In 13/54 (24.1%) subjects, an eumetabolic thyroid disease was found: plurinodular disease in 7/54 (13.0%); single nodule in 4/54 (7.4%); in 2/54 patients (3.7%), we found a malignant nodule characterized after total thyroidectomy as a classical PTC. Both patients were female and showed a classic FAP phenotype. Mutational analysis revealed in the first patient the APC germline mutation 3183_87del ACAAA and in the second patient the del9-10 (del9080dup11) novel APC variant; the first mutation has been already reported in association with PTC; to our knowledge the second mutation has never been previously reported in association with FAP. CONCLUSIONS: In the population examined, the estimated prevalence of thyroid malignant diseases was 3.7%. In both patients, the identified APC gene pathogenetic variants mapped within the 5' region of the gene, previously reported as a PTC-associated mutational hot spot. Both patients had classic FAP phenotype and genetic analysis revealed two pathogenetic APC mutations: c.3183_87delACAAA, a recurrent pathogenetic variant and del9-10 (del9080dup11), a novel, not previously described genomic rearrangement. In agreement with previous studies, the morpho-functional surveillance of thyroid in FAP series should be recommended. A better insight into the overall genotype-phenotype correlation of APC gene mutations would be helpful for the identification of at-risk individuals.

Helicobacter pylori diagnosis in patients with liver cirrhosis.

BACKGROUND: In cirrhotics, Helicobacter pylori infection is the major cause of peptic lesions, which are an important cause of upper intestinal haemorrhage in these patients. However, some diagnostic methods are not accurate for H. pylori detection in cirrhotics. AIMS: The study assessed the accuracy of different diagnostic methods for H. pylori detection in cirrhotics with and without gastroduodenal lesions. METHODS: The study population comprised of 53 cirrhotics. All patients underwent upper endoscopy: three biopsies were taken in the antrum and three in the gastric body. Four biopsies were used for Giemsa staining, while two were used for a rapid urease test. A blood sample was obtained for serology using Western blotting, and a [13C]urea breath test was performed in all patients. Histological assessment was regarded as the gold standard for diagnosis of H. pylori infection. RESULTS: H. pylori infection was detected at histological assessment in 28 (52.8%) patients. The [13C]urea breath test, rapid urease test, and serology were positive in 27 (51%) patients, 23 (43.4%) patients, and 34 (64.1%) patients, respectively. Sensitivity and specificity were 92.9 and 96% for the [13C]urea breath test, 78.6 and 96% for the rapid urease test, and 78.6 and 52% for serology. CONCLUSIONS: The [13C]urea breath test is very accurate in cirrhotics, whilst both serology and the rapid urease test give disappointing results.

Cholelithiasis: genetic hypothesis.

In inbred mice gallstone susceptibility is determined by Lith (lithogenic) genes which promote cholesterol hypersecretion in bile as a response to a high-fat diet. At least three major classes of proteins can be considered as candidate genes: (a) enzymes involved in cholesterol metabolism regulation; (b) trans-membrane carrier proteins from hepatocyte into bile; (c) cytosolic transfer proteins which regulate intrahepatocyte trafficking. The main candidates are: Spgp, a transmembrane protein which produces bile salt transport. Its gene map in Lith 1 region (Chromosome 2) and its expression is increased in susceptible inbred strains of mice (C57L) of inbred mice. Cmoat is a carrier protein that promotes the secretion of conjugated substances in bile. Its gene map in Lith 2 region (Chromosome 19) and its expression is increased in susceptible inbred strains of mice fed on a lithogenic diet. HGMR is the enzyme that regulates de novo synthesis of cholesterol in the liver. Its activity increases in resistant strains fed on a lithogenic diet and unvaries in susceptible strains. Its gene does not reside in any Lith region, but one Lith gene could be responsible for its activity regulation. To date, the hypothesis of a genetic basis of cholelithiasis in men has only been investigated in one study, in which the association of cholelithiasis and a mutation in the C7AH gene was documented in a group of Mexican patients.