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M Martinetti

Publications and source records attributed to M Martinetti.

At least 37 records · Page 2Linked to original sources
PubMed2000

A peculiar sequence motif in the alpha-1-domain of the HLA-C molecule in psoriasis.

BACKGROUND: Most immunogenetic studies restrict the location of the susceptibility gene for psoriasis to the HLA-C locus. OBJECTIVE: The present study evaluates the amino acid sequences of the HLA-C binding groove associated with the disease in a restricted population of Italian descent: Pavia, Northern Italy. METHOD: Forty patients, affected by psoriasis, underwent genomic analysis of exons 2 and 3 of the HLA-C gene by means of the PCR-SSP technique. RESULTS: The HLA-C*0602 gene frequency was significantly higher in patients with respect to 122 sex-, age- and ethnically matched controls (25 vs. 8.6%, chi(2) = 14.65, p = 0.000129). This frequency rose to 39.5% in patients with a family history positive for psoriasis. In particular, 4 amino acid substitutions were shown to be crucial for the predisposition to the disease, namely Ala 73 and Asn 77 (located in the C pocket of the antigen binding groove), Lys 80 in the F pocket and Asp 90 in the outer loop of the molecule. This peculiar motif, entirely located in the alpha(1)-domain of the HLA-C molecule, was characteristic of psoriatic patients being present in 77.5% of the cases against the 50.82% of controls (chi(2) = 8.77; p = 0.0031). Homozygosity for the amino acids considered at these residues was found in 15% of patients and in 0% of controls (chi(2) = 20.74, p = 0.0000053). CONCLUSION: The most important results emerging from this study indicate that Ala 73, Asn 77, Lys 80 and Asp 90 together form a motif restricted to few pathogenic peptides to be studied in the near future.

Age of Onset↗
PubMed2000

Low serum TNF-alpha levels in subjects at risk for type 1 diabetes.

OBJECTIVE: The aim of our study was to determine whether serum TNF-alpha levels in individuals at risk of developing type 1 diabetes, such as first-degree relatives of diabetic patients and children with incidental hyperglycemia, underwent alterations, and also to establish whether these levels might be used to identify individuals prior to insulin dependence. RESEARCH DESIGN AND METHOD: We studied 71 healthy first-degree relatives (FDR) of type 1 diabetic patients and 11 children with incidental hyperglycemia. We looked for immunogenetic (HLA class II serologic alleles and HLA-DQ alpha/beta genomic polymorphisms), immunologic (islet-cell and insulin autoantibodies) and metabolic (FPIR to IVGTT) markers of type 1 diabetic risk. Serum concentrations of TNF-alpha were quantified using IRMA. RESULTS: We found significantly lower serum TNF-alpha levels in FDR of type 1 diabetic patients (median: 54.3 pg/ml) (p=0.01) and in children with incidental hyperglycemia (median: 10.83 pg/ml) (p<0.0001) compared to controls (median: 76.56 pg/ml). No significant difference was observed between subjects with or without immunogenetic, immunologic and metabolic markers of type 1 diabetic risk. A negative correlation was found between serum TNF-alpha and HbA1c levels (r=-0.27, p=0.023). Two children with incidental hyperglycemia, whose TNF-alpha levels were very low, developed type 1 diabetes 6 and 8 months after this study. CONCLUSION: Our results are compatible with an impaired immune system in the prediabetic period and suggest that serum TNF-alpha concentrations may be considered as an immunological marker useful to identify subjects at risk of developing type 1 diabetes.

Alleles↗
PubMed1999

Human leukocyte antigen class II and III alleles and severity of hepatitis C virus-related chronic liver disease.

Hepatitis C outcome is likely related both to viral factors and host's immune responses. We correlated the severity of liver disease with human leukocyte antigen (HLA) genes (C4A, C4B, TNFA, TNFB, DRB1, DRB3, DRB4, DRB5, DQA1, DQB1, TAP1, and TAP2) in three groups of subjects: 99 patients with chronic hepatitis, 41 asymptomatic carriers, and 179 uninfected controls. Patients with grade/stage 3 to 4 hepatitis significantly differentiated for their low frequency of alleles TNFB*1, DRB1*1104, and DRB3*03, which had a protective role, and high frequency of allele DRB1*1001, which was associated with disease severity. HLA-DRB*11 subtypes were differentially distributed: DRB1*1104 was most frequent in carriers, whereas DRB1*1101 was more frequent in patients. The TAP1C,2A haplotype was also underrepresented in patients with respect to controls. Finally, a decrease of heterozygous subjects was observed in patients with respect to carriers at the DQB1 locus. Multivariate analysis by correspondence analysis and multiple logistic regression indicated that age, sex, and hepatitis C virus (HCV) type were the strongest risk factors; however, some immunogenetic variables (TNFB*1, DRB1*1104, and DRB3*03) showed an independent contribution, especially in comparing patients with extreme manifestations of disease. The involvement of different genes in various HLA subregions suggests that anti-HCV responses are modulated by a complex gene interplay rather than by single alleles.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Parental segregation of autoimmunity in patients with Turner's syndrome: preferential paternal transmission?

The prevalence of autoantibodies has been reported to be increased in both patients with Turner's syndrome and their parents. We evaluated organ-specific and non-organ-specific autoantibodies in 95 patients, ranging in age from infancy to adulthood, and in most of their parents, in order to determine the characteristics of autoimmune disorders in these families and to relate it to the genetic markers usually involved in autoimmunity (HLA, GM and KM genes). A statistically significant difference was observed between Turner patients and controls in the frequencies of organ-specific autoantibodies, in particular thyroid microsomal antibodies and thyroglobulin antibodies; however, the presence of autoantibodies was not associated with overt diseases in most cases. No significant difference was found between parents and controls. A study of the inheritance of the autoimmunity showed that transmission was preferentially paternal, since Turner patients had more chance of presenting autoantibodies when their fathers had autoantibodies rather than their mothers. A positive association was found between the presence of auto-antibodies and HLA-DR7;DQ2 and HLA-DR7;DQ9 haplotypes in Turner patients and fathers. No significant association was found between GM and KM allotype frequencies in Turner patients and their parents and the presence of autoantibodies. No epistatic interaction was demonstrated between HLA and GM or KM genes. Familial segregation was studied and a preferentially paternal transmission of HLA-DR7-carrying haplotypes and possibly also of the KM (1) allotype with autoimmunity was observed.

Adult↗
PubMed1999

Incompatibility for CD31 and human platelet antigens and acute graft-versus-host disease after bone marrow transplantation.

Bone marrow transplantation (BMT) is often complicated by acute graft-versus-host disease (aGVHD). In patients transplanted with an HLA-matched donor the occurrence of this complication is believed to be favoured by disparities at the minor histocompatibility antigens (mHA). However, few of these polymorphic molecules have been identified. We sought to determine whether donor/recipient incompatibility for HPA-1, HPA-2, HPA-3, HPA-5 or CD31 (codon 125) antigens represented a risk factor for aGVHD and genotyped these antigens in 70 bone marrow donors and their HLA-identical recipients. All patients were children who received BMT for haematological malignancies at a single institution according to well-defined therapy protocols. Statistical analysis showed that incompatibility for CD31 (codon 125) was a risk factor for grade II-IV aGVHD in the overall patient population, whereas HPA-3 incompatibility predicted aGVHD occurrence in HLA-A2 patients only. The magnitude of the aGVHD risk was directly related to the number of HPA/CD31 incompatibilities. No correlation was found between non-identity for HPA/CD31 and aGVHD. Since incompatibility but not non-identity for CD31 or HPA-3 was a risk factor for aGVHD, we suggest that allelic variants of these molecules can serve as mHA in BMT recipients from HLA-identical donors.

Adolescent↗
PubMed1999

Lymphocyte expression of human leukocyte antigen class II molecules in patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a multifactorial disorder, deriving from a combination of environmental and genetic factors. Polymorphisms of genes of the human major histocompatibility complex in COPD have been poorly studied in the past. In a preliminary approach, it was difficult to type human leukocyte antigen (HLA) at the protein level and it was hypothesized that there was a reduced surface density of HLA class II molecules. The aims of this study were to analyse, by cytofluorimetry, HLA class I and II molecule densities on peripheral mononuclear cells of COPD patients and to investigate whether there was a correlation with the polymorphisms of DQA and DQB promoter regions which are supposed to be important factors involved in surface expression of HLA-DQ molecules. The study investigated 27 male COPD patients admitted because of disease exacerbation and 49 healthy male controls. Quantitative analysis of fluorescence intensity of HLA class I (A, B, C) and class II (DR, DP, DQ) molecules was performed on blood mononuclear cells by cytoron cytofluorimetry. Polymorphisms of DQA and DQB promoters (QAP and QBP) were determined from the DNA (PCR-SSO). The surface densities of HLA class I and HLA-DQ molecules did not differ between the COPD patients and controls. HLA-DP molecule density seemed to be slightly, but not significantly lower in COPD, whereas surface HLA-DR molecules were significantly reduced (p < 0.005 vs controls). Frequencies of QAP alleles were not different between the COPD patients and controls, but the QBP 5.12 allele was significantly more frequent in COPD than in controls (chi 2 = 10.83, p = 0.0182, RR 5.5). In conclusion, individuals with exacerbated chronic obstructive pulmonary disease have reduced surface DR molecule expression and an increased frequency of the QBP 5.12 allele. The possible relationship between these two features and the possible role of cytokines in reducing human leukocyte antigen-DR expression in exacerbated chronic obstructive pulmonary disease is explored.

Adult↗
PubMed1998

Association between HLA class II alleles and protection from or susceptibility to chronic hepatitis C.

BACKGROUND/AIMS: Recent studies have suggested that the course of chronic hepatitis C may be influenced by the immunogenetic background of the host. Specifically, HLA-DR11 (5) has been associated with less advanced hepatitis C virus (HCV)-related liver disease. The aim of the present study was to investigate whether HLA-DRB1*11 subtypes or HLA-DQA1 and DQB1 genes might be associated with protection from or susceptibility to chronic HCV infection, histological severity of HCV-induced liver disease and infecting HCV genotype. METHODS: Ninety-nine unrelated outpatients with histologically documented chronic hepatitis C were studied and their allele frequencies were compared with those of 179 ethnically matched controls and with those of 41 HCV RNA-positive patients with persistently normal aminotransferase levels (HCV carriers). HLA-DQ types and HLA-DRB1*11 subtypes were determined by polymerase chain reaction gene amplification with sequence specific primers. RESULTS: None of 10 DQA1 or 12 DQB1 alleles was significantly associated with susceptibility to or protection from chronic HCV infection or with histological staging or with HCV genotype. However, analysis of DQA1-DQB1 combinations showed that DQA1*0201-DQB1*0201 combination was significantly more frequent in patients compared to controls, both in cis (26.3% vs 16.2%, p = 0.04, odds ratio = 1.8, 95% confidence interval, 0.96-3.5) and in trans (12.1% vs. 1.1%, p = 0.0001, OR = 12.2, 95% CI, 2.6-113.7). HCV carriers did not differ from controls or from patients in the frequency of DQA1-DQB1 combinations. The extended haplotype DRB1*1104, DQA1*0501, DQB1*0301 was seen significantly less frequently in patients than in controls (8% vs 22.3%, p = 0.0025, OR = 0.31, 95% CI, 0.12-0.7) or HCV-RNA carriers (8% vs 26.8%, p = 0.003, OR = 0.24, 95% CI, 0.08-0.73). CONCLUSIONS: Immunogenetic factors may play a role in determining both protection from and susceptibility to chronic hepatitis C, the trans-dimer DQA1*0201-DQB1*0201 predisposing to and the DRB1*1104, DQA1*0501, DQB1*0301 haplotype protecting from chronic hepatitis C.

Alleles↗
PubMed1998

Exaggerated 17-hydroxyprogesterone response to short-term adrenal stimulation and evidence for CYP21B gene point mutations in true precocious puberty.

OBJECTIVE: Following the observation of two patients affected by true precocious puberty who went on to develop polycystic ovary syndrome (PCOS) and who were found to be heterozygotes (carriers) for 21-hydroxylase deficiency (21-OHD), we decided to evaluate the frequency of heterozygosity for adrenal 21-OHD in patients with true precocious puberty. STUDY DESIGN: We investigated 32 girls affected by true precocious puberty, by the single-dose ACTH stimulation test, HLA typing and the molecular analysis of the CYP21B gene encoding for the 21-OH enzyme, in order to detect gene deletions or point mutations. Twenty-eight cases were on LHRH analogue treatment and the remaining four, untreated owing to parental refusal, were investigated 0.5-1.5 years after spontaneous menarche. RESULTS: After ACTH testing, 13 out of the 32 (41%) cases displayed higher 17-hydroxyprogesterone (17-OHP) levels than normal but less than those found in patients affected by nonclassical adrenal hyperplasia (CAH); these levels were similar to those observed in obligate heterozygotes for CAH due to 21-hydroxylase deficiency (21-OHD). HLA typing showed a significantly increased frequency of the HLA alleles A28 and B14 which are peculiar to the HLA haplotypes of nonclassical CAH due to 21-OHD. Molecular analysis of the CYP21B gene showed that in four out of the 10 tested patients with an exaggerated 17-OHP response there were heterozygous point mutations of the CYP21B gene. In contrast, no CYP21B gene abnormalities were detected in the eight tested patients with normal 17-OHP. No differences were found between carriers and non-carriers of the 21-OHD with regard to age at onset of precocious puberty, clinical features, bone age acceleration and gonadal suppression induced by LH-RH analogue treatment. Two out of the four untreated patients who were investigated after menarche were found to be carriers of the 21-OHD; these girls showed signs of androgen excess, irregular menses and polycystic ovaries. CONCLUSIONS: A high frequency of heterozygosity for adrenal steroid 21-OHD was found in our patients with true precocious puberty. This adrenal defect does not seem to influence the pattern of central precocious puberty, but these patients require long-term follow-up as they might go on to develop polycystic ovary syndrome (PCOS). Whether or not heterozygosity of the 21-OHD may be related to the premature activation of the hypothalamo-pituitary-gonodal axis remains to be defined.

17-alpha-Hydroxyprogesterone↗
PubMed1997

HLA class I and II genes in relation to the genetic structure and epidemiology of an Italian province.

The genetic structure of Pavia province is studied separately with HLA class I and II alleles. The analysis reveals that HLA class I genes reflect the same geographic barriers to migration found also with surnames, while class II gene distribution does not seem to be influenced by the presence of these barriers. The independence of HLA class II allelic distribution from the genetic structure of the area reinforces the hypothesis that environmental factors, rather than genetic drift, influence the frequency of these alleles. An example may be the significant correlation found between the distribution of the DR3-DQ2 haplotype and the prevalence of celiac disease in the province's districts.

Alleles↗
PubMed1996

The genetic structure of a province as revealed by surnames and HLA genes: potential utility in transplantation policy.

The combined use of surnames, which simulate selectively neutral genetic markers, and HLA genes may constitute a useful tool for the genetic survey of a small area. We found a coincidence between HLA genetic structure and surname "selectively neutral' pattern, in an Italian province, although HLA genes indicate a more pronounced genetic isolation for one particular subregion of the province. The patchiness of HLA allele distribution that is sometimes created by drift and/or selection can be used as the basis both of anthropological and of epidemiological studies. The creation of genetic maps of relatively small areas may also constitute a tool for the selection of bone marrow donors.

Cluster Analysis↗
PubMed1996

Hemophagocytic lymphohistiocytosis. Report of 122 children from the International Registry. FHL Study Group of the Histiocyte Society.

Hemophagocytic lymphohistiocytosis (HLH) is a rare, often fatal, disease of early infancy. The diagnosis of HLH is frequently delayed or made at autopsy because no genetic or biologic marker has been identified. To improve the classification and treatment of HLH, the Histiocyte Society has established an 'International Registry for HLH'. Data collected included family history, clinical and laboratory features at the onset of illness, and treatment outcome. Stringent diagnostic criteria (ie fever, splenomegaly, cytopenia, hypertriglyceridemia, and/or hypofibrinogenemia, and hemophagocytosis without evidence of malignancy) were used for patient selection. One hundred and twenty-two patients (61 males, 61 females) were enrolled from 17 centers in 11 countries. The rate of parental consanguinity was 24%. A positive family history was reported in 49% of cases including two pairs of affected male twins. The median age at disease onset was 2.9 months, with no difference between familial and sporadic cases. Age at onset was similar in affected sibs from 10 of 14 families, but in four up to 3-year differences were observed. Hemophagocytosis was present at diagnosis in 75%. An associated infection (usually by common viral pathogens) was reported in 50 of the 122 (41%) cases, of which 25 had familial disease. Natural killer activity was impaired in 36 of 37 patients studied. Chromosome analysis was normal in all tested patients. A decreased frequency of HLA-B7 and B8 alleles and increased frequency of HLA-B21 and DQ3 were observed. The estimated 5-year survival (SE) was 21% (18.7) for all patients. It was 66% (37.8) for patients who received allogeneic bone marrow transplant and 10.1% (9.6) for patients treated with chemotherapy alone (P=0.0001). None of the previously proposed prognostic indicators (age, associated infection, cerebrospinal fluid pleocytosis, family history) correlated with treatment outcome.

Age of Onset↗
PubMed1996

HLA gene frequencies and migration in an Italian province.

HLA class I (HLA-A, HLA-B) and class II (HLA-DR, HLA-DQ) gene frequencies in 6 subareas of Pavia province are calculated in two samples of bone marrow donors. We estimated the degree of genetic differentiation between the 6 sub-areas through the standardized variance FST. On the basis of the island migration model the number of migrants is estimated from FST and compared with the observed migration index in the province according to the 1991 census.

Bone Marrow Examination↗
PubMed1995

Anti-HBV neonatal immunization with recombinant vaccine. Part I. Critical appraisal for a long-lived antibody course.

This study involved 912 infants born to HBsAg-negative mothers from 1 May 1991 to 30 June 1992. The subjects were randomly allocated to an accelerated (Group A) or traditional (Group B) immunization schedule and immunized with 10 micrograms of recombinant HBV vaccine. At the end of the vaccinal cycle 98.14% of both groups were protected against HBV with a high percentage of high responders (88.1% group B and 68% group A). Following a random plan, 345 of the initial 912 infants (144 group A and 201 group B) were serologically evaluated, 15-18 months after the booster dose, to identify the level of long-lasting specific antibody. The data obtained allowed us to identify the non-responder subjects after the seroconversion, to propose the evaluation of antibody titre after the booster dose of vaccine and, because one year after the booster dose 5.6% of the subjects responsive at seroconversion have shown undetectable anti-HBsAg titre, to propose the elevation of the antibody level considered as protective at the end of the vaccinal cycle.

Hepatitis B↗
PubMed1995

Anti-HBV neonatal immunization with recombinant vaccine. Part II. Molecular basis of the impaired alloreactivity.

HLA study was performed in 9 absolute non-responder (serum titre of anti-HBsAg < 2 mIU ml-1) and 8 hyporesponder (serum antibody level between 2 and 9.9 mIU ml-1) babies who underwent, in neonatal period, HBV vaccination with Engerix B recombinant vaccine. The investigation pointed out that many of these subjects carry HLA haplotypes classically involved in autoimmune diseases: namely HLADR7; DQ2, DR4; DQ8 and DR3; DQ2. The genomic typing for DRB1, DRB3, DRB4, DRB5, DQA1, DQB1 and DPB1 genes revealed an increased frequency of the DRB1*0701; DQA1*0201; DQB1*0201 haplotype (23.5 vs 9.9% of the controls) and of DPB*0201 allele (42.3 vs 13.2% of controls). The polymorphism of Bf, C4A and C4B complement serum components, recognized as important "immune-function-related genes", pointed out an increased frequency of the null allele C4AQ0 (34.3 vs 6.8% of the controls) stressing the role of C4A serum complement component in response to foreign peptide. The immunogenetic investigation has been extended to 23 responder babies (titre of anti-HBsAg > 50 mIU ml-1), vaccinated with the same trial as the poor responders. The HLA frequencies observed in this group were comparable to those of control population and, with respect to the HLA markers cited above, absolutely different from the non/hyporesponder infants. From the HLA class II sequence analysis in the group of poor-responder babies some characteristics, peculiar to autoimmune diseases, have been observed: the majority of the infants showed at least an arginine at the 52 residue of the alpha chain of DQ molecule and a non-aspartic acid at the 57 position of the DQ beta chain.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗