TY - JOUR AU - Kaestner, Lisa-Ann AU - Lazarus, John AU - Salukazana, Azola AU - Muller, Elmi AU - Jehle, Karl-Heinz PY - 2023/05/16 Y2 - 2024/03/29 TI - A Case Series of Cystinuric Stone Formers in Western Cape, South Africa: SLC3A1 or SLC7A9 Mutations and Phenotype JF - Société Internationale d'Urologie Journal JA - Soc Int Urol J VL - 4 IS - 3 SE - Original Research DO - 10.48083/SRPF1472 UR - https://siuj.org/index.php/siuj/article/view/261 SP - 165-170 AB - Objective To describe the genetic mutations and phenotype in the first African series of patients with cystinuria.Methods Patients with cystinuria were recruited from a specialist metabolic renal stone clinic in Cape Town,South Africa, for DNA sequencing to detect mutations in SLC3A1 and SLC7A9. Chart reviews and patient interviewswere conducted to record demographics, previous medical history, family history, stone-specific history, age at firstpresentation, cystinuria complications, urine cystine:creatinine ratio, stone analysis, and serum creatinine.Results Nine patients were included: 3 male patients and 6 female patients. The mean age (± SD) of patients was33.43 ± 19.96 years. The median age (± IQR) at initial diagnosis of cystinuria was 16 ± 18 years, but the age ranged from2 to 66 years. Three of 9 patients included (33.3%) had chronic kidney disease (CKD); however, none were receivingdialysis. Most patients initially presented with a staghorn calculus (4/9; 44.4%). The mean serum creatinine (± SD) was84 ± 38 μmol/L. The mean urine cystine (± SD) was 2083 ± 1249 nmoL/mg creatinine. Eight patients had mutationsin the SLC3A1 gene; 1 had mutations in both SLC3A1 and SLC7A9. Of the patients with only SLC3A1 mutations,1 patient was homozygous and the rest were compound heterozygotes (two different mutations identified in the samegene). Four patients had a pathogenic variant in addition to an “uncertain significance” variant in SLC3A1. There were9 mutations (5 pathogenic and 4 “unknown significance”) in SLC3A1 and 1 mutation in SLC7A9. Two of these werenovel mutations.Conclusion This “first in Africa” series of cystinuria patients showed marked heterogeneity in both phenotype andgenotype, with a predominance of SLC3A1 mutations. This heterogeneity is similar to that reported in internationalcohorts. ER -