Neonatal presentation of a patient with Liddle syndrome, South Africa.

Introduction: Liddle syndrome is an autosomal dominantly inherited disorder usually arising from single mutations of the genes that encode for the alpha, beta and gamma epithelial sodium channel (ENaC) subunits. This leads to refractory hypertension, hypokalaemia, metabolic alkalosis, hyporeninaemia and hypoaldosteronism, through over-activation of the ENaC. Case presentation: We describe a 5-day old neonate who presented with severe hypernatraemic dehydration requiring admission to Steve Biko Academic Hospital in South Africa in 2012. Further evaluation revealed features in keeping with Liddle syndrome. Two compound heterozygous mutations located at different subunits encoding the ENaC were detected following genetic sequencing done in 2020. The severe clinical phenotype observed here could be attributed to the synergistic effect of these known pathological mutations, but may also indicate that one of the other variants detected has hitherto undocumented pathological effects. Management and outcome: This child's treatment course was complicated by poor adherence to therapy, requiring numerous admissions over the years. Adequate blood pressure control was achieved only after the addition of amiloride at the end of 2018, which raised the suspicion of an ENaC abnormality. Conclusion: To our knowledge, this is the first Liddle syndrome case where a combined effect from mutations resulted in severe disease. This highlights the importance of early recognition and management of this highly treatable genetic disease to prevent the grave sequelae associated with long-standing hypertension. Whole exome sequencing may assist in the detection of known mutations, but may also unveil new potentially pathological variants. What this study adds: This study highlights the importance of developing a high index of suspicion of tubulopathy such as Liddle syndrome for any child presenting with persistent hypertension associated with hypokalaemic metabolic alkalosis.

Genetic diversity of HHV8 subtypes in South Africa: A5 subtype is associated with extensive disease in AIDS-KS.

Human herpes virus 8 (HHV8) is the etiological agent of all forms of Kaposi's sarcoma (KS). Six major subtypes (A-F), based on genetic variability of open reading frame (ORF)-K1, have been identified. Numerous studies point to differing tumorigenic and pathogenic properties of the HHV8 subtypes. The study objectives were to determine the HHV8 subtypes and their prevalence in a cohort of clinical and histologically confirmed KS in Cape Town, South Africa, and analyze associations between the different subtypes and clinical presentation of KS. Clinical records were prospectively reviewed to extract clinical presentation; demographic data were retrospectively collected and tissue biopsies were taken for ORF-K1 subtyping. Eighty six patients were subtyped; 81 AIDS (acquired immune deficiency syndrome)-KS and 5 African endemic-KS. Subtype A5 (42/86) and B2 (16/86) predominated. B1, B3, A1 and A4 subtypes were identified in 10/86, 9/86, 4/86 and 1/86 patients, respectively. A5 and B subtypes were found in African blacks and individuals of mixed ancestry, while subtypes A1 and A4 were found only in whites and individuals of mixed ancestry. Subtype A5 was associated with >10 KS lesions at presentation in the AIDS cohort (adjusted OR: 3.13; CI: 1.02-9.58). Subtypes A1 and A4 combined were less likely to be associated with poor risk tumor extension (P = 0.031) and A1 was associated with lower likelihood of lower limb involvement (P = 0.019). In conclusion, these results indicate that subtype A5 and B predominate in South Africa and A5 may be associated with more extensive disease.

Kisspeptin regulation of genes involved in cell invasion and angiogenesis in first trimester human trophoblast cells.

The precise regulation of extravillous trophoblast invasion of the uterine wall is a key process in successful pregnancies. Kisspeptin (KP) has been shown to inhibit cancer cell metastasis and placental trophoblast cell migration. In this study primary cultures of first trimester human trophoblast cells have been utilized in order to study the regulation of invasion and angiogenesis-related genes by KP. Trophoblast cells were isolated from first trimester placenta and their identity was confirmed by immunostaining for cytokeratin-7. Real-time quantitative RT-PCR demonstrated that primary trophoblast cells express higher levels of GPR54 (KP receptor) and KP mRNA than the trophoblast cell line HTR8Svneo. Furthermore, trophoblast cells also expressed higher GPR54 and KP protein levels. Treating primary trophoblast cells with KP induced ERK1/2 phosphorylation, while co-treating the cells with a KP antagonist almost completely blocked the activation of ERK1/2 and demonstrated that KP through its cognate GPR54 receptor can activate ERK1/2 in trophoblast cells. KP reduced the migratory capability of trophoblast cells in a scratch-migration assay. Real-time quantitative RT-PCR demonstrated that KP treatment reduced the expression of matrix metalloproteinase 1, 2, 3, 7, 9, 10, 14 and VEGF-A, and increased the expression of tissue inhibitors of metalloproteinases 1 and 3. These results suggest that KP can inhibit first trimester trophoblast cells invasion via inhibition of cell migration and down regulation of the metalloproteinase system and VEGF-A.

Autosomal recessive hypercholesterolaemia: discrimination of ARH protein and LDLR function in the homozygous FH phenotype.

BACKGROUND: Phenocopies of homozygous familial hypercholesterolemia (hoFH) having autosomal recessive inheritance, were recently found to arise from defects in the LDL receptor (LDLR) adapter protein, called ARH, which facilitates the clearance of circulating LDL. Discrimination between the two causes of the phenotype at a clinical level may not be possible when parents display moderate hypercholesterolaemia. An effective strategy is thus required to identify the appropriate mechanism for the disorder. METHODS: Fibroblast LDL uptake studies were coupled with Western blotting for ARH protein in cell extracts, to identify the defective gene before DNA studies were initiated. Two subjects with the hoFH phenotype, but with indeterminate dyslipidaemia in their parents, were fully worked up. RESULTS: Defective LDL metabolism was established in both patients by functional and protein studies and further confirmed by detecting deleterious mutations, in the LDLR and ARH genes. The ARH patient is the first subject of Negroid identity to be described and records a specific mutation in this racial grouping. CONCLUSION: This study highlights the occasional complexity and uncertainty of a clinical diagnosis of hoFH and presents Western blotting of leucocyte extracts for ARH protein, as a rapid strategy for the detection of ARH before sequencing the gene for mutation(s). This strategy may be particularly useful in populations where founder mutations for ARH and LDLR defects are rare or co-exist.