The Incursion and Spread of Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4 Within South Africa

The report of a mass die-off of white-winged terns (Chlidonias leucopterus) along the shores of Lake Victoria in Uganda in January 2017 was a warning that highly pathogenic avian influenza (HPAI) H5N8 clade 2.3.4.4 had entered the avian populations of the African Rift Valley. In early June 2017, Zimbabwe reported an outbreak of the virus in commercial breeder chickens near Harare, and on June 19, 2017, the first case of HPAI H5N8 was confirmed in a broiler breeder operation near Villiers, Mpumalanga Province, South Africa, representing the first ever notifiable influenza in gallinaceous poultry in South Africa. Forty viruses were isolated from wild birds, backyard hobby fowl, zoo collections, commercial chickens, and commercial ostriches over the course of the outbreak and full genomes were sequenced and compared to determine the epidemiologic events in the introduction and spread of clade 2.3.4.4 H5N8 across the country. We found that multiple virus variants were involved in the primary outbreaks in the north-central regions of South Africa, but that a single variant affected the southernmost regions of the continent. By November 2017 only two of the nine provinces in South Africa remained unaffected, and the layer chicken industry in Western Cape Province was all but decimated. Two distinct variants, suggesting independent introductions, were responsible for the first two index cases and were not directly related to the virus involved in the Zimbabwe outbreak. The role of wild birds in the incursion and spread was demonstrated by shared recent common ancestors with H5N8 viruses from West Africa and earlier South African aquatic bird low pathogenicity avian influenza viruses. Improved wild bird surveillance will play a more critical role in the future as an early warning system.

Promoter region variation in NFE2L2 influences susceptibility to ototoxicity in patients exposed to high cumulative doses of cisplatin

Ototoxicity is a disabling reaction to cisplatin chemotherapy. Much of the inter-individual variability in the development of hearing impairment among cisplatin-receiving patients has not been fully accounted for. In particular, little is known about the pharmacogenomics of cisplatin-induced ototoxicity. This study sought to investigate the role of variation in five candidate genes in a cohort of South African cancer patients. Five variants within the candidate genes were genotyped in 214 patients, of which SLC22A2 rs316019 and NFE2L2 rs6721961 associated with reduced rates of ototoxicity. In the patients who were exposed to cumulative cisplatin doses ⩾200 mg m^-2 (n=113), the variant rs6721961 associated with ototoxicity according to three different grading scales of hearing loss (ASHA, P=0.005; Chang, P=0.028; CTCAE, P=0.004). The NFE2L2 promotor variant rs6721961 may therefore be protective against hearing loss in cisplatin-receiving cancer patients.

Genetic variation in Otos is associated with cisplatin-induced ototoxicity

BACKGROUND

Ototoxicity is an adverse drug reaction that may limit the effective use of cisplatin chemotherapy. Given the reported in vitro protective role of the gene Otos in response to cisplatin, this study aimed to explore the potential of Otos as a genetic modifier of ototoxicity.

PATIENTS & METHODS

One hundred South African cisplatin-receiving cancer patients with baseline and follow-up audiometric data were screened for variation in exonic target regions of Otos using direct cycle sequencing.

RESULTS

A total of 29 genetic variants were identified. The G alleles of Otos rs77124181 (c.-192-182C>G) and rs2291767 (c.-192-22A>G) were over-represented in ototoxicity-free patients (p = 0.022). Cumulative cisplatin dose and anatomical site of cancer were also associated with ototoxicity, while self-reported ethnicity associated with the ototoxic severity.

CONCLUSION

This study indicates a potentially protective role for the variant G alleles of SNPs rs77124181 and rs2291767 in Otos against the development of cisplatin-induced ototoxicity.

The co-inheritance of alpha-thalassemia and sickle cell anemia is associated with better hematological indices and lower consultations rate in Cameroonian patients and could improve their survival

Background

Co-inheritance of α-thalassemia was reported to be associated with a delayed age of disease onset among Cameroonian Sickle Cell Anemia (SCA) patients. The present study aimed to explore the correlation between α-thalassemia, hematological indices, and clinical events in these patients.

Methods and Findings

We studied 161 Cameroonian SCA patients and 103 controls (59.1% HbAA) with median ages of 17.5 and 23 years. RFLP-PCR was used to confirm SCA genotype and to describe haplotypes in the HBB-like genes cluster. Multiplex Gap-PCR was performed to investigate the 3.7 kb α-globin gene deletions. SNaPshot PCR, capillary electrophoresis and cycle sequencing were used for the genotyping of 10 SNPs in BCL11A, HMIP1/2, OR51B5/6 and HBG loci, known to influence HbF levels. Generalised linear regression models adjusted for age, sex and SNPs genotypes was used to investigate effects of α-thalassemia on clinical and hematological indices. The median rate of vaso-occlusive painful crisis and hospitalisations was two and one per year, respectively. Stroke was reported in eight cases (7.4%). Benin haplotype was the most prevalent (66.3%; n = 208 chromosomes). Among patients, 37.3% (n = 60) had at least one 3.7 kb deletion, compared to 10.9% (n = 6) among HbAA controls (p<0.001). Among patients, the median RBC count increased with the number of 3.7 kb deletions [2.6, 3.0 and 3.4 million/dl, with no, one and two deletions (p = 0.01)]. The median MCV decreased with the number of 3.7 kb deletion [86, 80, and 68fl, with no, one and two deletions (p<0.0001)], as well as median WBC counts [13.2, 10.5 and 9.8×10⁹/L (p<0.0001. The co-inheritance of α-thalassemia was associated with lower consultations rate (p = 0.038).

Conclusion

The co-inheritance of α-thalassemia and SCA is associated with improved hematological indices, and lower consultations rate in this group of patients. This could possibly improve their survival and explain the higher proportion of α-thalassemia among patients than controls.

Spondyloepimetaphyseal dysplasia with joint laxity (Beighton type); mutation analysis in eight affected South African families

Spondyloepimetaphyseal dysplasia with joint laxity (SEMD-JL), type 1 is an autosomal recessive disorder which has been identified in more than 30 affected children in the Afrikaans-speaking community of South Africa. Sequencing of B3GALT6 revealed a specific mutation, c.235A > G, in homozygous form in four families, while three others were compound heterozygotes for this mutation in combination with the c.200C > T mutation. In addition, a proband from one family carried the c.16C > T mutation combined with c.200C > T. In a series of five Iranian persons, mutations in B3GALT6 have been implicated in a syndrome characterised by skeletal abnormalities with intellectual disability, bone and connective tissue fragility. Other mutations in B3GALT6 resulted in the classical SEMD-JL phenotype in seven Japanese families and in a syndrome which has been likened to a progeroid form of Ehlers-Danlos syndrome (EDS). It is evident that there is considerable intragenic heterogeneity in B3GALT6. One of the mutations, c.200C > T, in the affected South Africans was also present in one of the Japanese persons and the respective phenotypes were identical. The multiplicity of allelic mutations and the phenotypic differences in the affected persons supports the concept that a spectrum of connective tissue disorders is programmed by mutations in B3GALT6.

Lynch syndrome: the influence of environmental factors on extracolonic cancer risk in hMLH1 c.C1528T mutation carriers and their mutation-negative sisters

Lynch Syndrome (LS) is a cancer susceptibility syndrome caused mostly by mutations in the mismatch repair genes, hMLH1, hMSH2 and hMSH6. Mutation carriers are at risk of colorectal and endometrial cancer and, less frequently, cancer of the ovaries, stomach, small bowel, hepatobiliary tract, ureter, renal pelvis and brain. The influence of environmental factors on extracolonic cancer risk in LS patients has not been investigated thus far. The aim of this study was to investigate some of these factors in South African females carrying the hMLH1 c.C1528T mutation and their mutation-negative relatives. Data were collected from 87 mutation-positive females and 121 mutation-negative female relatives regarding age, cancer history, hormonal contraceptive use, parity, duration of breast feeding, height, weight and age at first birth, last birth, menarche and menopause. Influence of these factors on cancer risk was analysed by mixed-effects generalised linear models. Extracolonic cancer occurred in 14% (12/87) of mutation-positive females versus 7% (8/121) of mutation-negative females, (P = 0.0279, adjusted for age and relatedness between women). Breast cancer was the most common extracolonic cancer. An association was found for oral contraceptive use and extracolonic cancer risk in mutation-negative females only. No association was found for any of the other risk factors investigated, when adjusted for age. This might be due to the scarcity of extracolonic cancers in our data. Future knowledge on the influence of additional environmental factors on cancer risk in LS females can lead to evidence-based lifestyle advice for mutation carriers, thereby complementing the prevention strategies available today. In addition, it can contribute to an integrated model of cancer aetiology. Therefore, this study should be taken as a thrust for further research.

Arg120stop nonsense mutation in the RP2 gene: mutational hotspot and germ line mosaicism?

Mutations in the RP2 gene account for up to 20% of X-linked recessive retinitis pigmentosa (RP). Arg120stop is to date the most frequently reported mutation found in RP2. Mutation screening was performed during the course of a large screening program of retinal degenerative disorders (RDDs) in South Africa using exon 1 and 2 of RP2 in 20 unrelated families with an X-linked mode of retinal degenerative inheritance. Direct sequencing analysis revealed a C-->T transition at position 358 in the proband in a family of German origin. Subsequent analysis revealed that this Arg120stop mutation cosegregated with the disease in an additional affected family member. The nonsense mutation, Arg120stop, could not however, be detected in the somatic cells of the obligate carrier female. This, the first report of a germ line mutation for a family with RP, has many implications for genetic counseling of retinal degeneration (RD). To avoid inaccurate risk assessment for RP due to epigenetic events, such as the rare occurrence of germ line mosaicism, genetic counseling in families with XLRP should always be guided by molecular testing.