Zorana Grubić

Asian Indian HLA-DR2-, DR4-, and DR52-related DR-DQ genotypes analyzed by polymerase chain reaction based nonradioactive oligonucleotide typing unique haplotypes and a novel DR4 subtype

We have employed a PCR-based nonradioactive technique using biotinylated SSOPs to define HLA-DR2-, 4-, DR51-, and DR52-associated DR-DQ genotypes in Asian Indian families. In the DR2 group, most haplotypes described by us in a previous study were confirmed by family analysis. Evidence for one additional haplotype was available in this study. The classic DRB1*1501- and DRB1*1502-associated caucasoid haplotypes occurred with an appreciable frequency in Asian Indians, but two of the DRB1*1601-associated Caucasoid haplotypes were absent. At least six unique and unusual DR2-associated genotypes were encountered. In the DR52 group, the three most common alleles are DRB1*0301, DRB1*1404, and DRB1*1101. The DR6-associated alleles were DRB1*1301, 1302, 1401, and 1404. A few unique haplotypes occurred with low frequency in this group. In the DR4 group, at least three unusual patterns of hybridization were noticed by family analysis. One of these appears to be a novel DR4 subtype upon sequencing. These results demonstrate that, besides HLA-DR2, appreciable complexity occurs in the DR4- and DR52-associated alleles among Asian Indians. The presence of unique DR-DQ haplotypes in addition to those found characteristically among Western Caucasians suggests that the Indian population provides valuable source of many HLA class II haplotypes.

HLA-A, HLA-B and HLA-DRB1 allele and haplotype diversity among volunteer bone marrow donors from Croatia

The determination of human leucocyte antigen (HLA)‐A, HLA‐B and HLA‐DRB1 alleles in the routine procedure of a volunteer hematopoietic stem cell (HSC) donors registration in the Croatian Bone Marrow Donor Registry (CBMDR) is performed to enhance the odds of finding a suitable HLA compatible donor for patients in need of a HSC transplantation worldwide. However, besides its original purpose, it also provides valuable information about the HLA polymorphism among Croats. The aim of the present study was to analyse the HLA allele and haplotype frequencies in a sample of 4000 donors from CBMDR. The distribution of HLA‐A, HLA‐B and HLA‐DRB1 alleles did not demonstrate significant differences from the data reported for other European populations. The higher frequency of B*40:02 allele in comparison with B*40:01 and DRB1*11:04 in comparison with DRB1*11:01 is interesting because it represents a difference in comparison with the Western and Northern European populations which are a main source of donors for Croatian patients. The haplotype frequencies show a greater variation and difference in comparison with data from other registries and populations; however, due to a lack of high‐resolution haplotype data, comparison was possible only with a very limited number of other populations.

Steroid 11-beta hydroxylase deficiency caused by compound heterozygosity for a novel mutation in intron 7 (IVS 7 DS+4A to G) in one CYP11B1 allele and R448H in exon 8 in the other

Congenital adrenal hyperplasia (CAH) due to steroid 11-beta hydroxylase deficiency (11β-OHD) is a rare genetic disorder of steroidogenesis transmitted as an autosomal recessive trait. We describe a new case of 11β-OHD CAH caused by compound heterozygosity for a novel mutation in intron 7 and previously described mutation in exon 8 of CYP 11B1 gene. A 2.5-year-old boy of Croatian descent presented with accelerated growth and bone age, borderline hypertension, and pseudoprecocious puberty. Hormonal studies established diagnosis of 11β-OHD: elevated plasma levels of 11-deoxycortisol, 17-hydroxyprogesterone, androstenedione and testosterone, low levels of cortisol and aldosterone, and suppressed plasma renin activity. Sequencing of the CYP11B1 gene identified compound heterozygous mutation consisting of a novel splicing mutation in intron 7 (IVS 7DS+4A to G) and R448H mutation in exon 8 previously reported mostly in Moroccan Jews. This is the first patient with CAH due to 11β-OHD in Croatia (and Slavic population in general) in whom molecular diagnosis of CYP11B1 gene was performed.

A new extended haplotype Cw*0602-B57-DRB1+0701-DQA1*0201-DQB1+0201 associated with psoriasis in the Croatian population

In this study, we have analysed the distribution of HLA class II alleles and the extended haplotype HLA‐Cw‐B‐DRB1‐DQA1‐DQB1 in Croatian patients with type I and type II psoriasis by hybridization with specific oligonucleotide probes. Type I psoriasis showed a significant association with the DRB1*0701 [P < 0.00001; relative risk (RR) = 5.83], DQA1*0201 (P < 0.00001; RR = 6.12), DQB1*0201 (P = 0.0006; RR = 3.29) and DQB1*0303 alleles (P = 0.0008; RR = 7.51). A negative correlation with type I disease was observed for the DQA1*0102 allele (P = 0.002; RR = 0.26). Type II psoriasis did not show any association with any class II alleles. The extended haplotype HLA‐Cw*0602‐B57‐DRB1*0701‐DQA1*0201‐DQB1*0201 was present at a significantly higher frequency in type I patients (P < 0.00001; RR = 7.72). However, this haplotype was not detected at all in patients with type II psoriasis. In conclusion, the extended haplotype HLA‐Cw*0602‐B57‐DRB1*0701‐DQA1*0201‐DQB1*0201 is a risk haplotype for type I disease in the Croatian population. This particular haplotype has not been reported previously in association with psoriasis in any other ethnic groups.

Two Novel CYP11B1 Gene Mutations in Patients from Two Croatian Families with 11 β -Hydroxylase Deficiency.

Steroid 11β-hydroxylase deficiency (11β-OHD) is the second most common cause of congenital adrenal hyperplasia. Mutations in the CYP11B1 gene, which encodes steroid 11β-hydroxylase, are responsible for this autosomal recessive disorder. Here, we describe the molecular genetics of two previously reported male siblings in whom diagnosis of 11β-OHD has been established based on their hormonal profiles displaying high levels of 11-deoxycortisol and hyperandrogenism. Both patients are compound heterozygous for a novel p.E67fs (c.199delG) mutation in exon 1 and a p.R448H (c.1343G>A) mutation in exon 8. We also report the biochemical and molecular genetics data of one new 11β-OHD patient. Sequencing of the CYP11B1 gene reveals that this patient is compound heterozygous for a novel, previously undescribed p.R141Q (c.422G>A) mutation in exon 3 and a p.T318R (c.953C>G) mutation in exon 5. All three patients are of Croatian (Slavic) origin and there is no self-reported consanguinity in these two families. Results of our investigation confirm that most of the CYP11B1 mutations are private. In order to elucidate the molecular basis for 11β-OHD in the Croatian/Slavic population, it is imperative to perform CYP11B1 genetic analysis in more patients from this region, since so far only four patients from three unrelated Croatian families have been analyzed.

High resolution definition of HLA‐DRB haplotypes by a simplified microsatellite typing technique

In humans, the region configurations DR1, DR8, DR51, DR52 and DR53 are known to display copy number as well as allelic variation, rendering high resolution typing of HLA-DRB haplotypes cumbersome. Advantage was taken of microsatellite D6S2878, present in all DRB genes/pseudogenes with an intact exon 2-intron 2 segment. This DRB-STR is highly polymorphic in composition and length. Recently, it was proven that all exon 2 sequences could be linked to a certain DRB-STR that segregates with the respective DRB allele. Because haplotypes show differential copy numbers and compositions of exon 2-positive DRB genes/pseudogenes, unique DRB-STR patterns could be described that appear to be specific for a particular DRB haplotype. The aim of this workshop project was to approve and to qualify this simple typing protocol in a larger panel covering different European populations. All participants succeeded in correctly defining the DRB-STR amplicons varying from 135 to 222 base pair (bp) lengths. The panel of 101 samples covered 50 DRB alleles distributed over 37 different haplotypes as defined by exon 2 sequence-based typing. These haplotypes could be refined into 105 haplotypes by DRB-STR typing. Thus, discrimination of exon 2-identical DRB alleles was feasible, as well as the exact description of three different crossing-over events that resulted in the generation of hybrid DR region configurations. This typing procedure appears to be a quick and highly robust technique that can easily be performed by different laboratories, even without experience in microsatellite typing; thus, it is suitable for a variety of researchers in diverse research areas.

STR and HLA analysis in paternity testing

Abstract During the 3-year period, 111 cases of paternity disputes were processed in our laboratory. The analysis was performed on nine STR (TH01, VWA31, FES/FPS, F13A01, SE33, D1S1656, D12S391, D18S535, and D22S683) loci and one VNTR (D1S80) locus. Out of 111 cases, 22 were exclusions. In all cases, exclusion was confirmed on at least five loci. STR loci that were informative in majority of cases were SE33 and D12S391. The least informative loci were FES/FPS and F13A01. In 21 cases exclusions were also confirmed by HLA class I, while only in 17 cases HLA class II alleles excluded the alleged father.

Distribution of KIR genes in the Croatian population

The KIR locus with genes involved in immune processes is among the most polymorphic and structurally diverse human loci. KIR genes encode activating and inhibitory receptors that differ in specificity for HLA class I ligands and signaling potential. These receptors are expressed principally by natural killer (NK) cells and subpopulations of T cells. This study represents the first report of the distribution of KIR genes, KIR genotypes and KIR/HLA pairs in 121 unrelated healthy Croatian individuals. Twenty-three different genotypes were observed in the Croatian population and all 16 KIR genes known to date were found. The most frequent KIR genotype was the AA genotype. All individuals had at least one inhibitory KIR/HLA pair with the majority of individuals with three inhibitory KIR/HLA pairs. The most frequent KIR/HLA pair was the KIR2DL3/C1 group. Our results demonstrated the similarity of the Croatian populations KIR repertoire with other Caucasian populations reported so far.

HLA allele and haplotype polymorphisms among Croatian patients in an unrelated hematopoietic stem cell donor search program

The aim of the present study was to investigate HLA alleles and haplotypes among Croatian patients in an unrelated HSCT program, and to analyze HLA matching in patient/donor pairs. Analysis was performed on a group of 105 patients and their donors, and 4000 unrelated donors from our registry (CBMDR) served as controls. PCR-SSO and PCR-SSP high-resolution methods for HLA-A, -B, -C, -DRB1, and -DQB1 loci were used for typing patient/donor pairs. Donors from CBMDR were tested for HLA-A, -B, and -DRB1 by PCR-SSO. No difference in frequency at HLA tested loci among patients and donors from CBMDR was observed. A fully matched donor (10/10) was found for 68 (64.8%) patients, and the highest number of mismatches was found for HLA-DRB1 and HLA-C alleles. The presence of HLA-B alleles (B*15:01, B*18:01, and B*51:01) associated with two or more HLA-C alleles as well as the presence of unusual HLA-B/HLA-C (B*35:01-C*07:01 and B*35:01-C*14:02) combinations resulted in mismatches at the HLA-C locus. Additionally, mismatches at the DRB1 locus were in most cases found for DRB1*11 alleles. The results suggest that the DRB1*11:04 allele might be considered as a limiting factor in finding a 10/10 matched donor. These data may help in the improvement of the searching protocol for unrelated donors for Croatian patients.

The study of the extended haplotypes of rare HLA-B*2730 allele using microsatellite loci

The aim of the present study was to compare haplotypes of the most frequent B*27 alleles among Croatians (B*2702 and *2705) and the rare B*2730 allele. For this purpose, 37 families with members carrying human leukocyte antigen (HLA)-B27 were selected. All individuals were analysed for eight microsatellites (Msats): D6S2927, short tandem repeat - MHC class I-related gene (STR_MICA), D6S2793, D6S2811, tumor necrosis factor a (TNFa), tumor necrosis factor d (TNFd), D6S273 and D6S1014, while individuals carrying the HLA-B27 specificity were subtyped. Of 39 analysed haplotypes, 20 individuals had B*2702, 15 subjects were positive for the B*2705 allele, the B*2730 allele was found in three haplotypes from different families, while one individual carried the B*2703 allele. HLA-A3 and -DRB1*16 were shared by all three B*2730 haplotypes. The DRB1*16 allele was also observed in the majority of B*2702 haplotypes (76.5%), while HLA-A3 was, after HLA-A2, the second most frequent HLA-A specificity in B*2702 haplotypes. No such correlation was found for the B*2705 haplotypes. Msat analysis showed that B*2730 haplotypes also share the same allele at all tested Msats. The D6S2927, D6S2793, MICA and TNFd Msats were not useful in distinguishing B*2702 and B*2705 alleles because D6S2927-213bp, STR_MICA-179bp, D6S2793-206bp, D6S2811-83bp and TNFd-130bp were detected in almost all cases. Conversely, for the TNFa, D6S273 and D6S1014 loci, haplotypes carrying B*2702 and B*2730 shared a single Msat allele in the majority of cases (TNFa-113bp, D6S1014-134bp and D6S273-134bp), which was not observed for B*2705 haplotypes. In conclusion, the similarity between B*2702 and B*2730 DNA sequences as well as their sharing of the same haplotypic combinations corroborates the proposed mechanism of B*2730 evolution from B*2702 by interallelic recombination.