RESUMO
Lysinuric protein intolerance (LPI) is an inborn error of dibasic amino acid transport due to a defect in the dibasic amino acid transporter in the renal and intestine and has a heterogenous presentation. Three Malaysian patients with LPI were studied and their biochemical and molecular findings compared. There were differences and similarities in the biochemical and molecular findings. Molecular analysis of SLC7A7 gene revealed a novel mutation c.235G>A; p.(Gly79Arg) in exon three in Patient 1 and a mutation c.1417C>T; p.(Arg473*) in exon 10 in patient 2 and 3. The degree of concentration of dibasic amino acids may determine the type of disease of the cell membrane transport, however, a positive molecular confirmation will secure the diagnosis.
RESUMO
We report three cases of cystinuria, presenting with urinary stones. A 2-year-old girl presented with urinary difficulty, hematuria, dysuria of sudden onset, and her 7-month-old younger brother also was presented with urinary difficulty, irritability on urination & stone passage. Other 6-month-old boy was admitted due to sudden onset anuria. They had radioopague renal & ureter stones and stone analysis revealed mixed cystine stones. The diagnosis of cystinuria was confirmed metabolic studies and stone analysis. Lrinary amino acid analysis showed excessive excretion of dibasic amino acids(cystine, ornithine, lysine, arginine). And they all had hypercalciuria and hyperuricosuria. They were treated with combination of percutaneous lithotripsy for large obstructing senes a nd an oral drug therapy with sodium bicarbonate for rendering the urine more alkaline, and alpha-mercaptopropionylglycine(ThiolaR). This form of treatment was sucessful in our three cases with elimination of recurrent nephrolithiasis, but in one patient, nephrotic syndrome possibly caused by ThiolaR was developed. The nephrotic syndrome was recovered spontaneously after cessation of Thiola. A review of literatures was also attempted briefly.