Annika Wennerström

Consistently Replicating Locus Linked to Migraine on 10q22-q23

Here, we present the results of two genome-wide scans in two diverse populations in which a consistent use of recently introduced migraine-phenotyping methods detects and replicates a locus on 10q22-q23, with an additional independent replication. No genetic variants have been convincingly established in migraine, and although several loci have been reported, none of them has been consistently replicated. We employed the three known migraine-phenotyping methods (clinical end diagnosis, latent-class analysis, and trait-component analysis) with robust multiple testing correction in a large sample set of 1675 individuals from 210 migraine families from Finland and Australia. Genome-wide multipoint linkage analysis that used the Kong and Cox exponential model in Finns detected a locus on 10q22-q23 with highly significant evidence of linkage (LOD 7.68 at 103 cM in female-specific analysis). The Australian sample showed a LOD score of 3.50 at the same locus (100 cM), as did the independent Finnish replication study (LOD score 2.41, at 102 cM). In addition, four previously reported loci on 8q21, 14q21, 18q12, and Xp21 were also replicated. A shared-segment analysis of 10q22-q23 linked Finnish families identified a 1.6-9.5 cM segment, centered on 101 cM, which shows in-family homology in 95% of affected Finns. This region was further studied with 1323 SNPs. Although no significant association was observed, four regions warranting follow-up studies were identified. These results support the use of symptomology-based phenotyping in migraine and suggest that the 10q22-q23 locus probably contains one or more migraine susceptibility variants.

HLA-DRB1 allele frequencies and C4 copy number variation in Finnish sarcoidosis patients and associations with disease prognosis.

Sarcoidosis is a multiorgan immune-mediated disease of unknown etiology with varying clinical pictures. We studied 3 genes in the major histocompatibility complex region (HLA-DRB1 and complement C4A and C4B) in patients with resolved disease after a 2-year follow-up (n = 90) and in patients whose disease was still active at that time point (n = 98) and compared them with controls (n = 150). Our primary aim was to detect genetic differences between the patient groups. We observed that the susceptibility allele for sarcoidosis was HLA-DRB1*15:01 (p = 0.011; odds ratio [OR] = 1.67) and the protective allele was HLA-DRB1*01:01 (p = 0.001; OR = 0.43). HLA-DRB1*03:01 was associated with resolving disease when compared with the persistent group (p = 0.011; OR = 2.22). The probability of having resolving disease was even greater if the patient had HLA-DRB1*03:01 and did not have extrapulmonary lesions (p = 0.001; OR = 3.39). By evaluating amino acid variants of the HLA-DRB1 gene, we determined that specific amino acids in pockets 4, 7, and 9 were associated with the prognosis of sarcoidosis. Our results support the importance of HLA-DRB1 as a predisposing gene for sarcoidosis. Particularly, HLA-DRB1*03:01 and polymorphisms of DRB1 pocket residues were associated with a favorable prognosis. Thus, accurate categorization of disease phenotype and HLA-DRB1 sequencing offer a basis for disease course estimation of sarcoidosis.

Major histocompatibility complex class II and BTNL2 associations in sarcoidosis

To the Editor: Sarcoidosis is a multiple organ immune-mediated disease of unknown aetiology. Identified genetic risk factors within the major histocompatibility complex (MHC), such as butyrophilin-like ( BTNL)2 , human leukocyte antigen ( HLA)-DRB1*03 and HLA-DRB1*15 , and protective factors, such as HLA-DRB1*01 , are found in many populations [1, 2]. The vast majority of sarcoidosis patients have a favourable prognosis, but approximately 20% develop a chronic, disabling disease [3]. Chronic beryllium disease (CBD) and chronic sarcoidosis share similarities as granulomatous diseases and they are pathologically indistinguishable from each other. CBD has been associated with HLA-DPB1*02:01 , especially with a glutamic acid residue at position 69 (Glu69) [4]. A functional splice-site polymorphism rs2076530 within the BTNL2 gene has been suggested to predispose to sarcoidosis [5]. However, previous studies have shown conflicting results as to whether HLA-DPB1 also predisposes to sarcoidosis, and whether the BTNL2 association is a result of linkage disequilibrium with HLA-DRB1 [6, 7]. The main objective of this study was to evaluate the HLA-DPB1 polymorphisms and the BTNL2 splice-site variant in Finnish patients suffering from sarcoidosis followed-up for 5–15 years and clinically categorised into subgroups based on disease prognosis. In addition, we constructed haplotypes containing MHC class II genes ( HLA-DRB1 and - DPB1 ) and rs2076530, and studied the influence of MHC markers and their combinations on disease susceptibility. We examined a total of 188 patients with verified pulmonary sarcoidosis. The patients were divided into those with a disease resolved within 2 years (n = 90) and those with persisting activity at …

Diversity of Extended HLA-DRB1 Haplotypes in the Finnish Population

The Major Histocompatibility Complex (MHC, 6p21) codes for traditional HLA and other host response related genes. The polymorphic HLA-DRB1 gene in MHC Class II has been associated with several complex diseases. In this study we focus on MHC haplotype structures in the Finnish population. We explore the variability of extended HLA-DRB1 haplotypes in relation to the other traditional HLA genes and a selected group of MHC class III genes. A total of 150 healthy Finnish individuals were included in the study. Subjects were genotyped for HLA alleles (HLA-A, -B, -DRB1, -DQB1, and -DPB1). The polymorphism of TNF, LTA, C4, BTNL2 and HLA-DRA genes was studied with 74 SNPs (single nucleotide polymorphism). The C4A and C4B gene copy numbers and a 2-bp silencing insertion at exon 29 in C4A gene were analysed with quantitative genomic realtime-PCR. The allele frequencies for each locus were calculated and haplotypes were constructed using both the traditional HLA alleles and SNP blocks. The most frequent Finnish A∼B∼DR -haplotype, uncommon in elsewhere in Europe, was A*03∼B*35∼DRB1*01∶01. The second most common haplotype was a common European ancestral haplotype AH 8.1 (A*01∼B*08∼DRB1*03∶01). Extended haplotypes containing HLA-B, TNF block, C4 and HLA-DPB1 strongly increased the number of HLA-DRB1 haplotypes showing variability in the extended HLA-DRB1 haplotype structures. On the contrary, BTNL2 block and HLA-DQB1 were more conserved showing linkage with the HLA-DRB1 alleles. We show that the use of HLA-DRB1 haplotypes rather than single HLA-DRB1 alleles is advantageous when studying the polymorphisms and LD patters of the MHC region. For disease association studies the HLA-DRB1 haplotypes with various MHC markers allows us to cluster haplotypes with functionally important gene variants such as C4 deficiency and cytokines TNF and LTA, and provides hypotheses for further assessment. Our study corroborates the importance of studying population-specific MHC haplotypes.

Evaluation of HLA-DRB1 imputation using a Finnish dataset.

Owing to the vast amount of alleles, high-resolution human leukocyte antigen (HLA) typing is expensive and time-consuming. Scientists have attempted to develop computational approaches to define HLA alleles with high confidence. We tested the reliability of HLA*IMP and SNP2HLA for imputing HLA-DRB1 alleles in a Finnish material (n=161). The per-individual success rates varied between 16.68% and 25.4% using both softwares. One of the most prominent example was HLA-DRB1*01:01 allele showing approximately a 30% success rate while being the most common wrongly imputed allele. In Finland, isolation and migration history have shaped the gene pool narrower showing HLA haplotype frequencies typical to the Finnish population when compared to Europeans. The imputation success for HLA-DRB1 alleles was very low pointing to the importance of population-specific reference material.

Peripheral hypertrophic subepithelial corneal degeneration: characterization, treatment and association with human leucocyte antigen genes

Purpose:  To evaluate the efficacy of keratectomy in treating irregular astigmatism caused by peripheral hypertrophic subepithelial corneal degeneration (PHSD) and to study the possible underlying immunological risk factors.

Novel 6p21.3 Risk Haplotype Predisposes to Acute Coronary Syndrome

Background—The HLA-DRB1*01 allele of the human leukocyte antigen has been associated with acute coronary syndrome. Genome-wide association studies have revealed associations with human leukocyte antigen and non–human leukocyte antigen genes of 3 major histocompatibility complex gene classes but not at allelic level. Methods and Results—We conducted a large-scale genetic analysis on a case–control cohort comprising 5376 acute coronary syndrome cases and 4852 unrelated controls from 4 populations of 2 European countries. We analyzed the risk candidate allele of HLA-DRB1*01 by genomic real-time polymerase chain reaction together with high-density single nucleotide polymorphisms of the major histocompatibility complex to precisely identify risk loci for acute coronary syndrome with effective clinical implications. We found a risk haplotype for the disease containing single nucleotide polymorphisms from BTNL2 and HLA-DRA genes and the HLA-DRB1*01 allele. The association of the haplotype appeared in 3 of the 4 populations, and the direction of the effect was consistent in the fourth. Coronary samples from subjects homozygous for the disease-associated haplotype showed higher BTNL2 mRNA levels (r=0.760; P<0.00001).We localized, with immunofluorescence staining, BTNL2 in CD68-positive macrophages of the coronary artery plaques. In homozygous cases, BTNL2 blocking, in T-cell stimulation assays, enhanced CD4+FOXP3+ regulatory T cell proliferation significantly (blocking versus nonblocking; P<0.05). Conclusions—In cases with the risk haplotype for acute coronary syndrome, these results suggest involvement of enhanced immune reactions. BTNL2 may have an inhibitory effect on FOXP3+ T cell proliferation, especially in patients homozygous for the risk alleles. Clinical Trial Registration—https://www.clinicaltrials.gov; Unique Identifier: NCT00417534.

The Effects of Intensive Weight Reduction on Body Composition and Serum Hormones in Female Fitness Competitors

Worries about the potential negative consequences of popular fat loss regimens for aesthetic purposes in normal weight females have been surfacing in the media. However, longitudinal studies investigating these kinds of diets are lacking. The purpose of the present study was to investigate the effects of a 4-month fat-loss diet in normal weight females competing in fitness-sport. In total 50 participants finished the study with 27 females (27.2 ± 4.1 years) dieting for a competition and 23 (27.7 ± 3.7 years) acting as weight-stable controls. The energy deficit of the diet group was achieved by reducing carbohydrate intake and increasing aerobic exercise while maintaining a high level of protein intake and resistance training in addition to moderate fat intake. The diet led to a ~12% decrease in body weight (P < 0.001) and a ~35–50% decrease in fat mass (DXA, bioimpedance, skinfolds, P < 0.001) whereas the control group maintained their body and fat mass (diet × group interaction P < 0.001). A small decrease in lean mass (bioimpedance and skinfolds) and in vastus lateralis muscle cross-sectional area (ultrasound) were observed in diet (P < 0.05), whereas other results were unaltered (DXA: lean mass, ultrasound: triceps brachii thickness). The hormonal system was altered during the diet with decreased serum concentrations of leptin, triiodothyronine (T3), testosterone (P < 0.001), and estradiol (P < 0.01) coinciding with an increased incidence of menstrual irregularities (P < 0.05). Body weight and all hormones except T3 and testosterone returned to baseline during a 3–4 month recovery period including increased energy intake and decreased levels aerobic exercise. This study shows for the first time that most of the hormonal changes after a 35–50% decrease in body fat in previously normal-weight females can recover within 3–4 months of increased energy intake.