Genetic and clinical characteristics of pediatric patients with familial hemophagocytic lymphohistiocytosis

Background

Our study was designed to investigate the frequencies and distributions of familial hemophagocytic lymphohistiocytosis (FHL) associated genes in Saudi patients.

Methods

FHL associated gene screening was performed on 87 Saudi patients who were diagnosed with hemophagocytic lymphohistiocytosis (HLH) between 1995 and 2014. The clinical and biochemical profiles were also retrospectively captured and analyzed.

Results

Homozygous mutations and mono-allelic variants were identified in 66 (75.9%) and 3 (3.5%) of the study participants, respectively. STXBP2 was the most frequently mutated gene (36% of patients) and mutations in STXBP2 and STX11 accounted for 58% of all FHL cases and demonstrated a specific geographical pattern. Patients in the FHL group presented at a significantly younger age than those belonging to the unknown-genetics group (median, 3.9 vs. 9.4 mo; P=0.005). The presenting clinical features were similar among the various genetic groups and the 5-year overall survival (OS) was 55.4% with a 5.6 year median follow-up. Patients with PRF1 mutations had a significantly poorer 5-year OS (21.4%, P=0.008) and patients undergoing hematopoietic stem cell transplant (72.4%) had a significantly better 5-year OS (66.5% vs. 0%, P=0.001).

Conclusion

Our study revealed the predominance of the STXBP2 mutations in Saudi patients with FHL. A genetic diagnosis was possible in 80% of the cohort and our data showed improved survival in FHL patients who underwent hematopoietic stem cell transplant.

ADAMTS19-associated heart valve defects: Novel genetic variants consolidating a recognizable cardiac phenotype

Recently, ADAMTS19 was identified as a novel causative gene for autosomal recessive heart valve disease (HVD), affecting mainly the aortic and pulmonary valves. Exome sequencing and data repository (CentoMD) analyses were performed to identify patients with ADAMTS19 variants (two families). A third family was recognized based on cardiac phenotypic similarities and SNP array homozygosity. Three novel loss of function (LoF) variants were identified in six patients from three families. Clinically, all patients presented anomalies of the aortic/pulmonary valves, which included thickening of valve leaflets, stenosis and insufficiency. Three patients had (recurrent) subaortic membrane, suggesting that ADAMTS19 is the first gene identified related to discrete subaortic stenosis. One case presented a bi-commissural pulmonary valve. All patients displayed some degree of atrioventricular valve insufficiency. Other cardiac anomalies included atrial/ventricular septal defects, persistent ductus arteriosus, and mild dilated ascending aorta. Our findings confirm that biallelic LoF variants in ADAMTS19 are causative of a specific and recognizable cardiac phenotype. We recommend considering ADAMTS19 genetic testing in all patients with multiple semilunar valve abnormalities, particularly in the presence of subaortic membrane. ADAMTS19 screening in patients with semilunar valve abnormalities is needed to estimate the frequency of the HVD related phenotype, which might be not so rare.

Preparation of anastrozole loaded PEG-PLA nanoparticles: evaluation of apoptotic response of breast cancer cell lines

Purpose

Anastrozole (ANS) is an aromatase inhibitor that is widely used as a treatment for breast cancer in postmenopausal women. Despite the wide use of ANS, it is associated with serious side effects due to uncontrolled delivery. In addition, ANS exhibits low solubility and short plasma half-life. Nanotechnology-based drug delivery has the potential to enhance the efficacy of drugs and overcome undesirable side effects. In this study, we aimed to prepare novel ANS-loaded PLA-PEG-PLA nanoparticles (ANS-NPs) and to compare the apoptotic response of MCF-7 cell line to both ANS and ANS-loaded NPs.

Method

ANS-NPs were synthesized using double emulsion method and characterized using different methods. The apoptotic response was evaluated by assessing cell viability, morphology, and studying changes in the expression of MAPK3, MCL1, and c-MYC apoptotic genes in MCF-7 cell lines.

Results

ANS was successfully encapsulated within PLA-PEG-PLA, forming monodisperse therapeutic NPs with an encapsulation efficiency of 67%, particle size of 186±27.13, and a polydispersity index of 0.26±0.11 with a sustained release profile extended over 144 hours. In addition, results for cell viability and for gene expression represent a similar apoptotic response between the free ANS and ANS-NPs.

Conclusion

The synthesized ANS-NPs showed a similar therapeutic effect as the free ANS, which provides a rationale to pursue pre-clinical evaluation of ANS-NPs on animal models.

A missense mutation in the CRBN gene that segregates with intellectual disability and self-mutilating behaviour in a consanguineous Saudi family

Background

Autosomal-recessive non-syndromic intellectual disability (ARNS-ID) is an aetiologically heterogeneous disorder. Although little is known about the function of human cereblon (CRBN), its relationship to mild cognitive deficits suggests that it is involved in the basic processes of human memory and learning.

Objectives

We aim to identify the genetic cause of intellectual disability and self-mutilation in a consanguineous Saudi family with five affected members.

Methods

Clinical whole-exome sequencing was performed on the proband patient, and Sanger sequencing was done to validate and confirm segregation in other family members.

Results

A missense variant (c. 1171T>C) in the CRBN gene was identified in five individuals with severe intellectual disability (ID) in a consanguineous Saudi family. The homozygous variant was co-segregating in the family with the phenotype of severe ID, seizures and self-mutilating behaviour. The missense mutation (p.C391R) reported here results in the replacement of a conserved cysteine residue by an arginine in the CULT (cereblon domain of unknown activity, binding cellular ligands and thalidomide) domain of CRBN, which contains a zinc-binding site.

Conclusions

These findings thus contribute to a growing list of ID disorders caused by CRBN mutations, broaden the spectrum of phenotypes attributable to ARNS-ID and provide new insight into genotype–phenotype correlations between CRBN mutations and the aetiology of ARNS-ID.

A study of KIR genes and HLA-C in Vogt-Koyanagi-Harada disease in Saudi Arabia

PURPOSE

Vogt-Koyanagi-Harada (VKH) disease is a serious ocular inflammatory autoimmune insult directed against antigens associated with melanocytes. The repertoire of killer cell immunoglobulin-like receptors (KIRs) is known to play a significant role in the pathogenesis of various autoimmune disorders. Accordingly, we sought to determine the incidence of KIR genes and KIR ligand (Human leukocytes antigen [HLA-C]) interaction in a cohort of Saudi VKH patients and to compare the findings to normal controls.

METHODS

A total of 30 patients with VKH and 125 control subjects were included. PCR using sequence-specific oligonucleotide primers were employed to determine the genotype of the KIR genes and HLA-C alleles.

RESULTS

The frequency of KIR2DS3 was significantly higher in the VKH patients than in the control group (p=0.048). Two unique genotypes; VKHN*1 and VKHN*2 were observed in the VKH patients and not in normal controls. In addition, the majority of the VKH patients (82%) in this study carry Bx genotypes that encode 2-5 activating KIR receptors. The genotype Bx5 was found to be positively associated with the VKH patients (p=0.053). Significantly higher homozygosity of HLA-C2 was observed in the VKH patients than in controls (p=0.005). Furthermore, HLA-C alleles-Cw*14 and Cw*17 were significantly prevalent in the VKH patients (p=0.037 and p=0.0001, respectively), whereas, Cw*15 significantly increased in the control group (p=0.0205). Among potential KIR-HLA interactions, we observed KIR2DL2/2DL3+HLA-C1 to be higher in the control subjects compared with the VKH patients (p=0.018).

CONCLUSIONS

Our findings indicated that KIR2DS3 and HLA-class I alleles (-Cw*14 and -Cw*17) may play a role in the pathogenesis of VKH disease. Additionally, the predominance of KIR2DL2/2DL3+HLA-C1 in the controls may imply that this KIR-ligand interaction could possibly play a role in the prevention of VKH disease, or could decrease its severity. These observations may contribute to our understanding of the pathogenesis of VKH and other autoimmune diseases.

Killer cell immunoglobulin-like receptor gene diversity in the Saudi population

Killer cell immunoglobulin-like receptors (KIRs) influence the outcome of haematopoetic stem cell transplantation by modulating the cytotoxic ability of natural killer (NK) cells and a subset of T cells. KIRs are also highly polymorphic and could therefore be good population genetic markers, much like their human leukocyte antigen (HLA) ligands. This study represents the first report on distribution of 16 KIR genes in 162 unrelated healthy Saudi individuals. All the 16 KIR genes were observed in the studied population and the four framework genes (KIR2DL4, 3DL2, 3DL3 and 3DP1) were present in all individuals. Forty- one distinct KIR profiles were expressed in our population, 11 of which had not been previously described in other populations including the Middle Eastern population. AA1, the most common genotypic profile was observed at a frequency of 26.5%. The group A haplotype was more frequent (53%) in the Saudi population compared to the group B haplotype (47%). The pattern of the inhibitory KIR/HLA ligands were also analyzed and 52.3% of the Saudi population was found to express two pairs of the inhibitory KIR/HLA-C. The KIR gene frequencies suggests that the Saudi population shares common general features with the Middle Eastern and other populations, but still has its own unique frequencies of several KIR loci.

HLA-DRB1 among patients with Vogt-Koyanagi-Harada disease in Saudi Arabia

PURPOSE

Vogt-Koyanagi-Harada (VKH) disease is an immune-mediated disorder with autoimmune insult directed against antigens associated with melanocytes. The genetic predisposition among VKH has not been explored in Saudi Arabia. So, the purpose of this study was to investigate the association of human leukocyte antigen (HLA)-DRB1 alleles to VKH patients and to clarify the molecular genetic mechanism underlying the susceptibility or resistance to VKH disease.

METHODS

Genomic DNA from a total of 30 patients with VKH and 29 control subjects was extracted from peripheral blood, and HLA-DRB1 alleles were typed by polymerase chain reaction and sequence based typing (SBT).

RESULTS

We found a statistically significant difference in the prevalence of HLA-DRB1 *0405 between the VKH patients and control subjects (p<0.05). Eleven out of thirty (36.6%) patients with VKH had positive HLA-DRB1 *0405 compared to two out of twenty-nine (6.9%) control subjects. However, there were no statistically significant differences in the HLA-DRB1 alleles *01, *0101, *0102, *0301, *04, *0403, *0404, *0701, *1001, *1101, *1112, *1301, *1302, *1303, *1501, and *1502 between the VKH patients and controls.

CONCLUSIONS

Patients with VKH had significantly greater incidence of HLA-DRB1 *0405 when compared to age and sex-matched controls. Consequently, this finding suggests that HLA-DRB1 *0405 allele might play a role in the pathogenesis of VKH disease.

Comparative study between the Light Cycler® and the PCR-restriction fragment length polymorphism in detecting factor V Leiden and factor II 20210G>A mutations

OBJECTIVES

To test reproducibility, speed and cost of testing for factor V Leiden and FII 20210G>A in our practice.

DESIGN AND METHODS

We compared conformity, reproducibility, speed and cost using the Light Cycler (LC) and PCR-RFLP.

RESULTS

There was 100% conformity and reproducibility. LC was faster but 23% more expensive per sample. When equipment depreciation and patient expenses are added, LC testing becomes cheaper.

CONCLUSION

In our practice, LC provides fast, reproducible and cost-effective results.