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Biomedical subjects

L Castaño

Publications and source records attributed to L Castaño.

At least 19 recordsLinked to original sources
PubMed2007

Association of KIR2DL5B gene with celiac disease supports the susceptibility locus on 19q13.4.

Genome-wide scans have detected linkage to celiac disease (CD) in several genomic locations, including 19q13.4. Killer immunoglobulin-like receptor (KIR) genes map to the region and encode receptors of natural killer (NK) cells and certain T cells that modulate cytolitic activity through interactions with HLA class I ligands, participating in the innate immune response. We performed KIR genotyping in a group of 70 CD patients of Basque origin and compared gene content, genotype and haplotype frequencies to ethnically matched blood-donors. The frequency of gene combination KIR2DL5B(+)/KIR2DL5A(-) was significantly higher in the disease group, and this result was confirmed in a second group of 343 CD patients and 160 controls of Spanish origin, suggesting an implication of this 'unexpressed' gene with increased susceptibility to CD (combined OR of 3.63 (95% CI: 1.76-7.51; P=0.0004)), possibly due to the lack of an efficient inhibitory signal. Our results support the role of the KIR gene cluster in celiac disease and replicate the CD-susceptibility locus at 19q13.4.

Celiac Disease↗
PubMed2006

Conserved extended haplotypes discriminate HLA-DR3-homozygous Basque patients with type 1 diabetes mellitus and celiac disease.

The major susceptibility locus for type 1 diabetes mellitus (T1D) maps to the human lymphocyte antigen (HLA) class II region in the major histocompatibility complex on chromosome 6p21. In southern European populations, like the Basques, the greatest risk to T1D is associated with DR3 homo- and heterozygosity and is comparable to that of DR3/DR4, the highest risk genotype in northern European populations. Celiac disease (CD) is another DR3-associated autoimmune disorder showing certain overlap with T1D that has been explained by the involvement of common genetic determinants, a situation more frequent in DR3-rich populations, like the Basques. As both T1D- and CD-associated HLA alleles are part of conserved extended haplotypes (CEH), we compared DR3-homozygous T1D and CD patients to determine whether CEHs were equally distributed between both disorders or there was a differential contribution of different haplotypes. We observed a very pronounced distribution bias (P<10(-5)) of the two major DR3 CEHs, with DR3-B18 predominating in T1D and DR3-B8 in CD. Additionally, high-density single nucleotide polymorphism (SNP) analysis of the complete CEH [A*30-B*18-MICA*4-F1C30-DRB1*0301-DQB1*0201-DPB1*0202] revealed extraordinary conservation throughout the 4.9 Mbp analyzed supporting the existence of additional diabetogenic variants (other than HLA-DRB1*0301-DQB1*0201), conserved within the DR3-B18 CEH (but not in other DR3 haplotypes) that could explain its enhanced diabetogenicity.

Celiac Disease↗
PubMed2005

Heterogeneity of vitamin D receptor gene association with celiac disease and type 1 diabetes mellitus.

OBJECTIVE: Vitamin D has been shown to exert multiple immunomodulatory effects and is known to suppress T-cell activation by binding to the vitamin D receptor (VDR). To determine whether VDR gene polymorphisms are related to the susceptibility to celiac disease, we investigated its implication as a candidate gene in the Basque population. Because celiac disease and type 1 diabetes share common susceptibility loci, we also analyzed families with type 1 diabetes mellitus. METHODS: A total of 37 families with celiac disease and 64 type 1 diabetic families of Basque origin with at least one affected offspring were genotyped for four VDR restriction-site polymorphisms (Fok I, Bsm I, Apa I and Taq I). The AFBAC approach was used to test for association. RESULTS: Comparison of VDR genotypes of the patients with those of 88 healthy individuals identified "ff" as a risk genotype for celiac disease [p = 0.01; OR = 3.45 (1.12-10.79)]. On the other hand, a significantly higher frequency of haplotype "fBAt" was observed in the type 1 diabetic group [p(c) = 0.02; OR = 4.4 (1.5-15.3)]. CONCLUSION: Our findings suggest that polymorphisms within the vitamin D receptor gene are markers of susceptibility to or protection from autoimmune diseases, although, at least in the Basque population, association of VDR variants with celiac disease and type 1 diabetes seems to be heterogeneous.

Celiac Disease↗
PubMed2002

HLA-DRB1 and MHC class 1 chain-related A haplotypes in Basque families with celiac disease.

The contribution of HLA genes to the genetic risk for celiac disease (CD) has been known for a long time. Recent publications have pointed to the possibility that a second, independent susceptibility locus could be located in the same genomic region, and a triplet repeat polymorphism in exon 5 of the gene MHC class I chain-related protein A (MICA; located between TNFA and HLA-B) has been associated with several autoimmune disorders, including type 1 diabetes mellitus (DM1) and Addison's disease. On the other hand, a single amino acid change in exon 3 of MICA (M129V) has been shown to strongly reduce MICA binding to NKG2D, an activating natural killer receptor expressed also on T cells, and this could have significant effects on autoimmune reactions. In this study, we have analyzed the contribution of these polymorphisms to CD in 37 Basque families, and have constructed MICA-HLA-DRB1 haplotypes to determine whether MICA has an effect independent from the HLA class II conferred risk. In our population, HLA-DRB1*0301 was associated with an increased risk for CD, while HLA-DRB1*1501 conferred protection from the disease (OR: 7.38 and 0.06, respectively). On the other hand, MICA allele A4 was positively associated with the disease (OR: 4.69) whereas allele A9 showed a trend towards protection (OR: 0.18), although significance did not hold after correction. No association of the exon 3 biallelic polymorphism was observed. A positive allelic association was found for haplotypes A5.1-DRB1*0301 (associated with risk for disease), A4-DRB1*0301 and A6-DRB1*07. In view of our results, both HLA-DRB1 and MICA are associated with CD, but stratification analysis did not show any independent contribution of the MICA polymorphisms analyzed to CD risk. Besides, MICA allele A4 (also A5.1 was associated with risk for CD and other diseases) is in strong linkage disequilibrium with HLA-DRB1*0301. Finally, the major histocompatibility complex region's conferred susceptibility to CD, at least in Basque, is very similar to that observed for DM1, with shared risk and protective haplotypes.

Adolescent↗
PubMed2001

Branchio-oto-renal syndrome: identification of a novel mutation in the EYA1 gene.

Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder characterized by the association of branchial cysts or fistulae, external ear malformation and/or preauricular pits, hearing loss, and renal anomalies. Mutations in the EYA1 gene, a human homologue of the Drosophila 'eyes absent' gene, have been identified as cause of the syndrome. We report here two families with BOR syndrome. In one family, with the complete phenotype, a novel splice site mutation in exon 15 (1599 +1 G to A) is described. No mutations in the EYA1 gene were found in a second family presenting with ear pits, deafness, and renal anomalies, but lacking branchial fistulae. These and other findings from the literature suggest the existence of genetic heterogeneity of the BOR, BO, and other related phenotypes, with two or more genes involved.

Branchio-Oto-Renal Syndrome↗
PubMed2001

Familial hypercalcemia and hypercalciuria: no mutations in the Ca2+-sensing receptor gene.

A 6-year-old boy presented with persistent hypercalcemia, hypercalciuria and nephrocalcinosis from early infancy. His 40-year-old father also had hypercalcemia and hypercalciuria. In both individuals serum values of intact parathyroid hormone (PTH) were repeatedly normal. Although these findings suggest a functional abnormality of the calcium-sensing receptor (CaR), no mutations in coding regions of the CaR gene could be demonstrated.

Adult↗
PubMed2001

Molecular analysis of hereditary hyperferritinemia-cataract syndrome in a large Basque family.

Hereditary hyperferritinemia-cataract syndrome is a genetic condition characterized by constitutively increased serum ferritin values in the absence of iron overload and by bilateral cataract. It has been demonstrated that mutations in the stem loop structure of the iron regulatory element (IRE) located in the 5'-untranslated region of the ferritin L-subunit gene (19q13.1) are responsible for the anomalous expression of this protein. Although not clearly explained, cataract formation seems secondary to the increased levels of ferritin in the lens. We analyzed a large Basque family in order to identify possible germline alterations of the iron regulatory element of the ferritin-L gene in affected individuals and first-degree relatives. All members of the family presented hyperferritinemia and cataract except a young child who had hyperferritinemia but did not present cataract. Sequence analysis permitted the identification of an A40-->G mutation in all members, including this child. This could demonstrate that cataract formation is a consequence of ferritin accumulation in the lens.

5' Untranslated Regions↗
PubMed2000

The [HLA-B18, F1C30, DR3] conserved extended haplotype carries a susceptibility gene for IgD deficiency.

We showed previously that the conserved extended MHC haplotype [HLA-B8, SCO1, DR3] carries recessive susceptibility genes for IgA and IgG4 deficiency and dominant genes for IgD and IgG3 deficiency. [HLA-B18, F1C30, DR3] has similar class II and III regions to [HLA-B8, SC01, DR3] and is common in the Basques. We therefore studied serum immunoglobulin concentrations in Basque homozygotes, heterozygotes, and noncarriers of (FIC30, DRB1*0301, DRB3*02, DQA1*0501. DQB1*0201) (F1C30, DR3). As shown by others, no subjects were deficient in IgA, IgM, or IgG subclasses. In contrast, 29% of homozygotes and three of seven double heterozygotes with (SC01, DRB1*0301, DRB3*0101, DQA1*0501, DQB1*0201) (presumed homozygotes for IgD deficiency susceptibility genes) were IgD deficient. Thus, 32% of presumed homozygotes were IgD deficient compared with 1.6% of noncarriers. Of haplotype heterozygotes, 25% were IgD deficient. The high frequency of IgD deficiency in both homozygotes and heterozygotes for (F1C30, DR3) suggests a partially penetrant dominant susceptibility gene for IgD deficiency on [HLA-B18, F1C30, DR3].

Diabetes Mellitus, Type 1↗
PubMed2000

Influence of sex and age at onset on autoantibodies against insulin, GAD65 and IA2 in recent onset type 1 diabetic patients.

METHODS: Autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA) and tyrosine phosphatase IA2 (IA2A) were measured in sera from 448 recent onset patients with type 1 diabetes mellitus (DM) subdivided according to sex (194 female and 254 male) and age at onset (134 patients diagnosed before 10 years, 187 between 10 and 20 years, 66 between 20 and 30 years and 61 over 30 years. RESULTS: Autoantibodies were more frequent in female DM patients (93.8 vs. 86.6%, p = 0.013) due to an increased prevalence of both GADA (86.1 vs. 70.1%) and IA2A (59.3 vs. 49.2%), with GADA levels also significantly higher in women (0.24 vs. 0.18 U, p = 0.0003). When age groups were compared, there was a reduction in prevalence in patients over 20 years for both IAA (70% for patients diagnosed under 20 and 36% for older patients) and IA2A (65 and 25%, respectively). These differences also affected IAA levels, with the highest antibody titres in the youngest group (1,214.1 nU/ml in children under 10 compared to 546.9, 345.6 and 341.1 nU/ml in the subsequent groups; p < 10(-4)). GADA prevalence did not differ significantly between age groups but, nevertheless, autoantibody levels were highest among the oldest type 1 DM patients (0.327 U compared to 0.216, 0.197 and 0.176 U in the decreasing age groups; p < 10(-4)). CONCLUSION: There are sex- and age-related differences affecting the presence and/or titres of beta cell autoantibodies. We speculate that these differences could reflect the severity and specificity of the autoimmune attack against the endocrine pancreas and might influence the rate of progression to type 1 DM or the risk of developing other autoimmune diseases.

Adolescent↗
PubMed2000

Analysis of chromosome 6q in Basque families with type 1 diabetes. GEPV-N. Basque-Navarre Endocrinology and Paediatric Group.

Over the last few years several studies of linkage between non-HLA loci and type 1 diabetes mellitus have mapped several putative susceptibility genes on chromosome 6q; in fact, positive evidence of linkage and/or association of IDDM5 (6q25), IDDM8 (6q27) and IDDM15 (6q21) with type 1 diabetes has been reported. We have studied these loci in diabetic families of Basque origin, a genetically homogeneous population, to avoid artifactual association results due to admixture within the sample analysed. Statistical analyses of linkage were performed using a transmission disequilibrium test (TDT). We could not confirm linkage for IDDM5, IDDM8 and IDDM15 in our population, possibly due to population-specific differences in genetic susceptibility and/or environmental triggering factors to type 1 diabetes.

Adult↗
PubMed1999

Multiple endocrine neoplasia type 1 (MEN1): clinical heterogeneity in a large family with a nonsense mutation in the MEN1 gene (Trp471Stop).

OBJECTIVE: Familial multiple endocrine neoplasia type 1 (MEN1) is an hereditary dominant trait characterized by tumours of the parathyroids, anterior pituitary and endocrine pancreatic glands, among others. The MEN1 gene has recently been cloned, and MEN1-mutations have been identified in several families as well as in a number of sporadic cases. The aim of this study was to search for mutations in a large MEN1-family in order to define the clinical heterogeneity among mutation-carriers. We also analysed DNA from several tumour tissues in order to test the 'two hit' model for inactivation of the MEN1 gene. PATIENTS AND METHODS: We searched for mutations in the MEN1-gene in members of a large MEN1-family. A total of 11 affected and 4 healthy at risk individuals were analysed. DNA was obtained and exons 1 to 10 of the MEN1-gene were PCR-amplified and subjected to automated-direct sequencing. In addition, we isolated DNA from parathyroid tumours of two family members, and compared this DNA with that of the normal tissue counterpart to define if the normal copy of the MEN1-gene was deleted. RESULTS: G to A change at nucleotide 7640 (exon 10) that would convert Trp to Stop at codon 471 was found. This mutation was identified in eleven affected individuals, as well as in four healthy (asymptomatic) family members. These patients showed a wide spectrum of clinical symptoms and ages of presentation. Comparison of normal and tumour DNAs showed the loss of the normal (non-mutated) copy of MEN1 gene in the tumour tissue. CONCLUSION: The different ages of disease presentation and the heterogeneity of symptoms among carriers of the Trp471Stop mutation, which would lead to the synthesis of a truncated non-functional protein, suggest that clinical heterogeneity is a characteristic of MEN1 independent of the type of mutation. Finally, the lack of amplification of the normal MEN1-allele on DNA from parathyroid tumours of two family members indicates that MEN1 is a tumour suppressor gene, the second hit that inactivates the normal copy in mutation carriers being a deletion.

Adolescent↗
PubMed1999

Molecular analysis in familial neurohypophyseal diabetes insipidus: early diagnosis of an asymptomatic carrier.

Familial neurohypophyseal diabetes insipidus (FNDI) is an inherited deficiency of the hormone arginine vasopressin (AVP) and is transmitted as an autosomal dominant trait. In the present study we have analyzed the AVP-neurophysin II (AVP-NPII) gene in a Spanish kindred. Studies were performed on seven members (four clinically affected) of the family. Patients were diagnosed at the Hospital Universitario Gregorio Marañón (Madrid, Spain). The entire coding region of the AVP-NPII gene of all family members was amplified by PCR and sequenced. All affected individuals presented a missense mutation (G1757-->A) that replaces glycine at position 23 with arginine within the NPII domain. The substitution was confirmed by restriction endonuclease analysis and was present in heterozygosis. Additionally, one of the asymptomatic relatives (a girl 8 months old at the time of study) was identified as carrier of the same mutation and developed the disease 3 months later. The alteration found in the second exon of the gene in this family seems to be responsible for the disease, as all individuals harboring the mutation had been previously diagnosed or have eventually developed FNDI. Identification of the molecular defect underlying FNDI in affected families is a powerful tool for early asymptomatic diagnosis in infants.

Arginine Vasopressin↗
PubMed1998

Anomalous behaviour of the 5' insulin gene polymorphism allele 814: lack of association with Type I diabetes in Basques. GEPV-N Group. Basque-Navarre Endocrinology and Paediatrics.

A susceptibility locus (IDDM2) for Type I (insulin-dependent) diabetes mellitus has been identified as allelic variation at a variable number of tandem repeats polymorphic region upstream of the human insulin gene. In Caucasian populations, individuals homozygous for the short length alleles (26 to 63 repeats: class I) have a two- to fivefold increased risk of developing the disease, while the long alleles (more than 140 repeats: class III) are dominantly protective. Recent evidence has shown that class I alleles are not equally predisposing, and in particular, the 42-repeat allele (allele 814) can be protective when paternally inherited. We have assessed the contribution of IDDM2 to disease in a group of Basque families with Type I diabetes. As in other Caucasoid populations, we found that class I alleles, as a whole, are associated with an increased risk of developing the disease. Using a polymerase chain reaction-based assay to more accurately resolve the different sizes of individual class I alleles, we identified 14 different variants and observed that allele 814 has an anomalous behaviour in Basques, being the only class I allele that does not have an increased frequency in the diabetic alleles group. These findings provide additional support for the recently published allele-specific effects of IDDM2 in Type I diabetes pathogenesis.

Adolescent↗