CTLA4 gene polymorphism in Italian patients with colorectal adenoma and cancer.

BACKGROUND AND AIMS: Colorectal cancer is a major health problem. Colonoscopic colorectal cancer screening is cumbersome and expensive. Identification of genetic risk of colorectal cancer may help to select the subjects who could benefit from colonoscopy. The immune system plays a fundamental role in the human-environment interaction, and the carcinogenic effects of many environmental factors are mediated by the chronic activation of the immune system in a genetic-controlled fashion. Cytotoxic T lymphocyte associated antigen 4 (CTLA4) plays an inhibitory role in regulating lymphocyte functions. The loss of CTLA4 function is responsible for loss of mucosal lymphocyte tolerance. The G allele at position +49 of exon 1 of the CTLA4 gene affects the CTLA4 function. We evaluated in an association study the role of CTLA4 A+49G polymorphism as a risk factor for colorectal neoplasm. PATIENTS AND METHODS: Five hundred and fifty-six patients (male 295; female 261) who underwent colonoscopy at our Centre were enrolled in the study and divided into three groups: Colorectal cancer (132 patients, M/F 68/64, mean age 66+/-11 years); Colorectal adenoma (186 patients, M/F 110/76, mean age 65+/-11 years); Healthy controls (238 patients, M/F 117/121, mean age 63+/-10 years). DNA was extracted from peripheral blood, CTLA4 gene was amplified by using specific primers, and A+49G polymorphism was analysed by restriction enzyme digestion. RESULTS: No statistically significant differences in the genotype distribution among Control and Adenoma groups (p=0.93), Control and Carcinoma groups (p=0.52), and Adenoma and Carcinoma groups (p=0.53) were observed. CONCLUSION: There is no significant correlation between CTLA4 A+49G polymorphism and the risk of colorectal neoplasm among Italian Caucasians.

Recurrent mutations in the iron regulatory element of L-ferritin in hereditary hyperferritinemia-cataract syndrome.

BACKGROUND AND OBJECTIVE: Hereditary hyperferritinemia-cataract syndrome (HHCS) is an autosomal dominant disorder characterized by bilateral cataracts and increased serum and tissue L-ferritin, in the absence of iron overload. The deregulation of ferritin production is caused by heterogeneous mutations in the iron regulatory element (IRE) of L-ferritin that interfere with the binding of iron regulatory proteins. DESIGN AND METHODS: We have identified several patients from three unrelated Italian families with HHCS. Iron parameters were assessed by standard methods. The IRE element of L-ferritin was amplified by PCR using appropriate primers and directly sequenced. RESULTS: Ferritin levels ranged from 918 microg/L to 2490 microg/L in the patients studied. In one family bilateral cataracts were diagnosed early in life, whereas in the others cataracts were diagnosed around 40-50 years. The female proband of family 3 presented with a severe iron deficiency anemia, which was unrecognized because of the increased ferritin values. Sequencing of the IRE element of L-ferritin in the probands of the three families identified three different nucleotide substitutions (+32 GAE A, +40 AAE G and +39 CT) in the IRE of L-ferritin. These mutations have already been reported in unrelated subjects of different ethnic origins. INTERPRETATION AND CONCLUSIONS: Our findings are consistent with recurrent mutations associated with HHCS and underline the importance of this syndrome in the differential diagnosis of unexplained hyperferritinemia. In addition, the findings highlight the role played by transferrin saturation in the diagnosis of iron deficiency in these patients.

Juvenile hemochromatosis locus maps to chromosome 1q.

Juvenile hemochromatosis (JH) is an autosomal recessive disorder that leads to severe iron loading in the 2d to 3d decade of life. Affected members in families with JH do not show linkage to chromosome 6p and do not have mutations in the HFE gene that lead to the common hereditary hemochromatosis. In this study we performed a genomewide search to map the JH locus in nine families: six consanguineous and three with multiple affected patients. This strategy allowed us to identify the JH locus on the long arm of chromosome 1. A maximum LOD score of 5.75 at a recombination fraction of 0 was detected with marker D1S498, and a LOD score of 5. 16 at a recombination fraction of 0 was detected for marker D1S2344. Homozygosity mapping in consanguineous families defined the limits of the candidate region in an approximately 4-cM interval between markers D1S442 and D1S2347. Analysis of genes mapped in this interval excluded obvious candidates. The JH locus does not correspond to the chromosomal localization of any known gene involved in iron metabolism. These findings provide a means to recognize, at an early age, patients in affected families. They also provide a starting point for the identification of the affected gene by positional cloning.

Generation of a transcription map of a 1 Mbase region containing the HFE gene (6p22).

A transcription map was generated of a 1 Mb interval including the HFE gene on 6p22. Thirty-seven unique cDNA fragments were characterised following their retrieval from hybridisation of immobilised YACs to primary pools of cDNAs prepared from RNA of foetal brain, human liver, foetal human liver, placenta, and CaCo2 cell line. All cDNA fragments were positioned on the physical map on the basis of presence in aligned and overlapping YACs and cosmid clones of the region. The isolated cDNAs together with established or published sequence tagged sites (STSs) and markers provided sufficient landmark density to cover approximately 90% of the 1 Mb interval with cosmid clones. The precise localisation of two known genes (NPT1 and RING finger protein) was established. A minimum of 14 additional transcription units has also been integrated. Twenty-eight cDNA fragments showed no similarity with known sequences, but 20 of these detected discrete mRNAs upon northern analysis. Their characterisation is still under investigation. Eleven new polymorphisms were also identified and localised, and the HFE genomic structure was better defined. This integrated transcription map considerably extends a recently published map of the HFE region. It will be useful for the identification of genetic defects mapping to this region and for providing template resources for genomic sequencing.

Juvenile and adult hemochromatosis are distinct genetic disorders.

Juvenile Hemochromatosis (JH) is a rare genetic disorder that causes iron overload. JH clinical features are similar to those of hemochromatosis (HFE), but the clinical course is more severe and is characterized by an earlier onset and by a prevalence of cardiac symptoms and endocrine dysfunctions. Here we describe seven Italian patients belonging to five unrelated families with clinical features typical of JH. In four out of five families the parents were consanguineous. Analysis of HFE gene mutations in all the cases and nucleotide sequence of the gene in one case excluded this gene as responsible for JH. Segregation analysis of 6p markers closely associated with HFE in families with consanguineous parents clearly showed that JH is unlinked to 6p and thus genetically distinct from HFE.