Genetic relationship between Murcia Region (SE Spain) and other populations in the Iberian Peninsula and Mediterranean area with respect to HFE gene mutations distribution

Genotypic Frequencies of Mutations Associated with Alpha-1 Antitrypsin Deficiency in Unrelated Bone Marrow Donors from the Murcia Region Donor Registry in the Southeast of Spain

Alpha-1 antitrypsin (AAT1) deficiency (AAT1D) is an inherited disease with an increased risk of chronic obstructive pulmonary disease (COPD), liver disease, and skin and blood vessel problems. AAT1D is caused by mutations in the SERPINE1 gene (Serine Protease Inhibitor, group A, member 1). Numerous variants of this gene, the Pi system, have been identified. The most frequent allelic variants are Pi*M, Pi*S, and Pi*Z. The development of COPD requires both a genetic predisposition and the contribution of an environmental factor, smoking being the most important. Studies on this deficiency worldwide are very scarce, and it is currently considered a rare disease because it is underdiagnosed. The aim of this study was to analyze the genotypic frequencies of mutations associated with AAT1 deficiency in unrelated bone marrow donors from the donor registry of the Region of Murcia in southeastern Spain due to the high risk of presenting with different pathologies and underdiagnosis in the population. A total of 112 DNA-healthy voluntary unrelated bone marrow donors from different parts of the Region of Murcia were analyzed retrospectively. AAT1 deficiency patient testing involved an automated biochemical screening routine. The three main variants, Pi*M, Pi*Z, and Pi*S, were analyzed in the SERPINE1 gene. Our results showed a frequency of 3.12% of the Pi*Z (K342) mutation in over 224 alleles tested in the healthy population. The frequency of Pi*S (V264) was 11.1%. The frequency of the haplotype with the most dangerous mutation, EK342 EE264, was 4.46%, and the frequency of EK342 EV264 was 1.78% in the healthy population. Frequencies of other EE342 EV264-mutated haplotypes accounted for 18.7%. As for the EE342 VV264 haplotype, 0.89% of the total healthy population presented heterozygous for the EV264 mutation and one individual presented homozygous for the VV264 mutation. In conclusion, the frequencies of Pi mutations in the healthy population of the Region of Murcia were not remarkably different from the few studies reported in Spain. The genotype and haplotype frequencies followed the usual pattern. Health authorities should be aware of this high prevalence of the Pi*S allelic variant and pathological genotypes such as Pi*MZ and Pi*SZ in the healthy population if they consider screening the smoking population.

Allelic diversity of MICA gene and MICA/HLA-B haplotypic variation in a population of the Murcia region in southeastern Spain

Major histocompatibility complex class I-related chain A (MICA) is located at 46 kb centromeric of HLA-B. It is highly polymorphic and interacts with NKG2D, its receptor on the surface of NK, Tgammadelta and T CD8 lymphocytes. Data on MICA polymorphism in different populations are still limited. Our aim was to establish allelic diversity of MICA gene and linkage disequilibrium with HLA-B in our population. DNA was obtained from 154 unrelated healthy individuals from the Murcia region in southeastern Spain. HLA-B genotyping was performed using polymerase chain reaction (PCR)-sequence-specific oligonucleotide probes and allele-specific PCR-sequence-specific primers, and MICA genotyping by using PCR-sequence-specific oligonucleotide probes. A total of 19 MICA alleles were detected on this study. MICA*008 was the most frequent allele (25.3%), followed by MICA*002 (16.1%), MICA*004 (14.9%), MICA*001 (7.8%), MICA*009 and MICA*016 (7.1%), and MICA*010 (4.6%). Eleven alleles had frequencies of <1%. In the haplotype analysis, MICA*008-B*0702 was found to be the most common, followed by MICA*004-B*4403 and MICA*001-B*1801, MICA*002-B*3501, MICA*008-B*4402, MICA*004-B*4901, MICA*008-B*0801, and MICA*002-B*3801. The frequency of MICA*010-B*1501, MICA*008-B*1302, MICA*015-B*4501, and MICA*008-B*4001 was remarkable inasmuch as these two last haplotypes have not been reported in Spanish population. Indeed, MICA*016 linked to B*1402 has also not been reported in the literature. In conclusion, the allelic diversity in our population is similar to other Caucasian populations; however we found a series of less frequent alleles, in addition to as-yet-undescribed haplotypic associations in other populations of Caucasian origin.