HLA class II polymorphism in Saudi patients with multiple sclerosis.

Several studies have investigated the association of different HLA antigens with multiple sclerosis (MS). However, only few studies have considered the association of high-resolution HLA type and MS with none yet from Saudi Arabia. The aim of this study was to investigate the association of HLA class II alleles with MS in the Saudi population. We used next-generation sequencing to investigate HLA association with MS. This study was conducted at King Abdulaziz Medical City in Riyadh, Saudi Arabia. We found that several HLA-DRB1 and DQB1 alleles were associated with MS. These alleles included HLA-DRB1*15:01 (odds ratio [OR]: 3.01; 95%, confidence interval [CI]: 1.68-5.54; P = .0001), HLA-DQB1*02:01 (OR: 1.76; 95% CI: 1.20-2.58; P = .0022), HLA-DQB1*06:02 (OR: 3.52; 95% CI: 1.87-6.86; P < .0001), and HLA-DQB1*06:03 (OR: 2.42; 95% CI: 1.16-5.25; P = 0.01). Interestingly, HLA-DRB1*15:01 was associated with increased risk of previous relapses. In addition, HLA-DRB1*15:01 and HLA-DQB1*06:02 were found to be associated with lower vitamin D levels. This study provides insights on the association of different HLA alleles with clinical characteristics and outcome of MS among Saudis. These insights can have future implications for the clinical management of MS based on the patient genetic profile.

The prevalence of CCR5-Δ32 mutation in a cohort of Saudi stem cell donors.

CCR5 is a chemokine receptor that was found to be used by HIV as a co-receptor for entering target cells. A 32 bp deletion was described in certain people that rendered CCR5 non-functional. The mutant allele CCR5-Δ32 has been shown to prevent HIV infection. In addition, stem cell transplantation with the CCR5-Δ32 homozygous genotype can lead to clearance of HIV infection. In this study, our aim was to investigate the frequency of CCR5-Δ32 mutation in a cohort of stem cell donors from cord blood bank and stem cell donor registry. A total of 3025 samples were collected from healthy stem cell donors (2625) and from cord blood units (400). DNA was extracted and the CCR5 gene was amplified by polymerase chain reaction (PCR) in a light cycler system using SYBR Green dye. The mutated gene was further confirmed by direct gene sequencing. We found 38 heterozygous for CCR5-Δ32 and one homozygous CCR5 mutation (Δ32/Δ32) out of the 3025 tested individuals. We conclude that the protective CCR5-Δ32 allele appears to be rarely present in Saudi Arabia.

Identification of the HLA-DQB1*06:123 allele in an unrelated stem cell donor from the Saudi Registry.

HLA-DQB1*06:123 differs from HLA-DQB1*06:29 by six nucleotide substitutions resulting in five amino acid changes.

Description of a novel HLA-DQB1 allele, HLA-DQB1*06:126, in the Saudi stem cell donor registry.

HLA-DQB1*06:126 differs from HLA-DQB1*06:02:01 by a nonsynonymous C to T substitution at nucleotide position 1621 in Exon 2.

Three new HLA-C alleles (HLA-C*14:02:13, HLA-C*15:72 and HLA-C*15:74) in Saudi bone marrow donors.

Three new HLA-C alleles were identified by sequence-based typing method (SBT) in donors for the Saudi Bone Marrow Donor Registry (SBMDR). HLA-C*14:02:13 differs from HLA-C*14:02:01 by a silent G to A substitution at nucleotide position 400 in exon 2, where lysine at position 66 remains unchanged. HLA-C*15:72 differs from HLA-C*15:22 by a nonsynonymous C to A substitution at nucleotide position 796 in exon 3, resulting in an amino acid change from phenylalanine to leucine at position 116. HLA-C*15:74 differs from HLA-C*15:08 by a nonsynonymous C to T substitution at nucleotide position 914 in exon 3, resulting in an amino acid change from arginine to tryptophan at position 156.

A novel HLA-DQ allele, HLA-DQB1*05:48, found in the Saudi Stem Cells Donor Registry.

The allele HLA-DQB1*05:48 differs from HLA-DQB1*05:01:01 by a non-synonymous T to C substitution at nucleotide position 1693 in exon 2.

Two novel alleles HLA-A*02:433 and HLA-A*02:434 identified in Saudi bone marrow donors using sequence-based typing.

In this report, we present two novel HLA-A alleles: HLA-A*02:433 and HLA-A*02:434. These alleles were identified by sequence-based typing method (SBT), in two donors for the Saudi Bone Marrow Donor Registry (SBMDR). Allele A*02:433 is identical to A*02:05:01G except for a G to A substitution at nucleotide position 449 in exon 2. This substitution results in glycine to serine substitution at position 83. Whereas, allele A*02:434 is identical to A*02:01:01G except for a C to A substitution at nucleotide position 245 in exon 2, which results in phenylalanine to threonine substitution at position 15. The generation of both alleles appears to be the result of nucleotide point mutation involving 02:01:01 and 02:05:01.

Two novel alleles HLA-DRB1*11:150 and HLA-DRB1*14:145 identified in Saudi individuals.

Two new HLA- DRB1 alleles were identified by sequence-based typing method (SBT) in 1100 participants in the Saudi Stem Cell Donor Registry. HLA-DRB1*11:150 differs from HLA-DRB1*11:01:01G by a single C to A substitution at nucleotide position 5580 in exon 2, resulting in an amino acid change from alanine to glutamic acid at position 74. HLA-DRB1*14:145 differs from HLA-DRB1*14:04 by a C to G substitution at nucleotide position 5511 in exon 2, resulting in an amino acid change from threonine to arginine at position 51.

CTLA-4 gene polymorphism and its association with Graves' disease in the Lebanese population.

Graves' disease is an organ-specific autoimmune disease that has a female predominance. It is probably the result of a complex interaction of genetic and environmental factors. This disease is characterized by immune system activation, evidenced by elevated serum thyroid-specific autoantibodies and lymphocytic infiltration of the target organ (the thyroid gland), associated with raised levels of circulating activated T lymphocytes. Several reports have demonstrated genetic linkage and association between the genetic markers of the CTLA-4 gene on chromosome 2q33 and Graves' disease. In order to confirm this association in the Lebanese population, a bi-allelic A/G polymorphism at position 49 of CTLA-4 exon 1 was studied in 34 patients with Graves' disease, and in 38 healthy individuals, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The results showed a significant increase in allele and genotype frequencies in patients with Graves' disease compared to controls. This suggests that the CTLA-4 gene might play a role in the development of Graves' disease in the Lebanese population.

Association of transforming growth factor beta-1 single nucleotide polymorphisms with radiation-induced damage to normal tissues in breast cancer patients.

PURPOSE: To investigate whether transforming growth factor beta-1 (TGFbeta1) single nucleotide polymorphisms were associated with the susceptibility of breast cancer patients to severe radiation-induced normal tissue damage. MATERIALS AND METHODS: PCR-RFLP assays were performed for TGFbeta1 gene polymorphisms on DNA obtained from 103 breast cancer patients who received radiotherapy. The G-800A, C-509T, T+869C and G+915C polymorphic sites were examined, and genotype and allele frequencies of two subgroups of patients were calculated and compared. RESULTS: The less prevalent -509T and +869C alleles were significantly associated with a subgroup of patients who developed severe radiation-induced normal tissue fibrosis (n=15) when compared with those who did not (n=88) (odds ratio=3.4, p=0.0036, and 2.37, p=0.035, respectively). Furthermore, patients with the -509TT or +869CC genotypes were between seven and 15 times more likely to develop severe fibrosis. CONCLUSIONS: These findings imply a role for the -509T and +869C alleles in the pathobiological mechanisms underlying susceptibility to radiation-induced fibrosis. Their predictive value would be limited to patients who are -509TT or +869CC, but if "fibrosis-associated" polymorphic sites in other genes could be identified, it may be possible to detect fibrosis prone individuals before radiotherapy with greater certainty.

Increased gelatinase activity in systemic sclerosis dermal fibroblast cultures with unaltered gelatinase A mRNA expression.

Gelatinase A is one of the matrix metalloproteinases, the principle enzymes degrading extracellular matrix (ECM) and basement membrane components. The aim of this study was to study gelatinase expression in systemic sclerosis (SSc). Fibroblasts were grown from uninvolved and involved skin of SSc patients and from healthy controls. Gelatinase activity was assayed by degradation of tritium-labeled gelatin. Gelatinase A mRNA was quantitated by competitive reverse transcriptase-polymerase chain reaction (RT-PCR). Gelatinase activity was significantly increased in both uninvolved and involved SSc cultures. However, gelatinase A mRNA was unaltered in both cases. Neither SSc nor control skin fibroblasts expressed gelatinase B, indicating that the increased gelatinase activity is not due to gelatinase B induction. Gelatinase A is a specific basement membrane degrading enzyme, so increased gelatinase activity may be related to the pathophysiology of SSc by initiating microvascular damage and leakage of substances capable of producing further endothelial cell damage or fibroblast activation. Increased gelatinase activity in SSc fibroblasts seems to be regulated at translational and/or post-translational level.

Somatostatin receptor subtype 2 mediates somatostatin inhibition of ion secretion in rat distal colon.

BACKGROUND & AIMS: Somatostatin peptides are potent inhibitors of intestinal ion secretion, providing the rationale for their use in treating secretory diarrhea. However, the nature of the receptors that mediate these effects is unclear. The aims of this study were to investigate expression of somatostatin receptor subtypes (SSTRs) 1-5 in rat colonic epithelium and to identify which subtype(s) mediate inhibition of adenosine 3', 5'-cyclic monophosphate (cAMP)-activated secretion using SSTR-selective analogues. METHODS: SSTR expression was determined by reverse-transcription polymerase chain reaction and immunoblotting. Effects of somatostatin analogues on electrogenic ion secretion were studied in isolated colonic mucosa mounted in Ussing chambers. RESULTS: Crypt epithelium expressed messenger RNA for SSTR1 and SSTR2 and low levels of SSTR5. A splice variant of SSTR2 (SSTR2B) was also detected. The SSTR2 selective analogue NC-812 was a potent inhibitor of forskolin-activated secretion and cAMP accumulation. In contrast, peptides selective for SSTR3 (DC-25/12) and SSTR5 (DC-23/99) were weak inhibitors of secretion. NC-812 also inhibited dibutyryl cAMP-activated secretion, indicating a site of action distal to cAMP production. Immunoblot analysis confirmed expression of a 93-kilodalton SSTR2 protein in crypt cell membranes. CONCLUSIONS: SSTR2 receptors expressed by colonocytes mediate somatostatin's antisecretory actions in rat colon. Somatostatin analogues directed to specific SSTRs may provide the basis for more selective antidiarrheal drugs.