Urinary cystine calculi and detection of polymorphism in the SLC3A1 gene in Sudanese children

Abstract

To investigate polymorphism in exon 8 of the SLC3A1 gene in children with urinary cystine calculi in Khartoum. Methods A semi-quantitative chemical method was used to analyse 175 urinary calculi removed surgically from paediatric patients at Soba Teaching Hospital in Khartoum between October 2005 and May 2009. DNA was extracted with phenol chloroform isoamyl alcohol, and exon 8 of the SLC 3A1 gene was amplified in a thermocycler and sequenced with an AB3130 genetic autoanalyser. Results Of the 175 stones, 10 were cystine calculi (5.7%). The sex ratio of the patients was 2.3:1 (boys to girls), and the mean age at cystine stone onset was 31.1 ± 28.2 months (range, 3-125 months). Of the 10 patients, 8 had a positive family history of calculi formation, 4 had bilateral calculi, 3 had both renal and urinary bladder calculi, and 2 had obstructive acute renal failure. All patients required more than one surgical operation. One patient had a missense mutation M467K in exon 8 of the SLC3 A1 gene. Conclusion The prevalence of cystine calculi among urinary calculi in Sudanese children was 5.7%. A family history was found in 80% of children. A mutation (M467T) was identified at exon 8 of the SLC 3A1 gene in one child.