PMC2800027_01
Pedigree of family with patient that carry mutation in SLC7A9, electropherograms of DNA sequencing for G173R mutation, and the result of oral cystine load in the patient. (A) Pedigree of family with patient; mutation in SLC7A9 and urine dibasic amino acid excretion. Urine amino acid excretion values for cystine (Cys), lysine (Lys), arginine (Arg), and ornithine (Orn) are expressed in microM/g creatinine (normal range: Cys, 30-130; Lys, 150-630; Arg, 30-110; Orn, 30-90). (B) Point mutation G173R (535G A substitution) in SLC7A9 gene localized in exon 5. Patient's sequence has both G (normal) and A (mutant) at nucleotide 535, resulting in the presence of Gly (codon GGA) and Arg (codon AGA). (C) Changes in plasma cystine level after an oral L-cystine dihydrochloride load of 0.25 mM/kg body weight in the patient.
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F1
Quantitative amino acid analysis of the urine disclosed increased excretion of cystine (1,345 microM/g Cr) and an excess of the dibasic amino acids; ornithine, lysine, and arginine (Fig. 1A). The oral cystine loading test resulted in elevation of plasma cystine levels (Fig. 1C). His mother and sister were screened by quantitative amino acid analysis of the urine and showed variable degree of cystine and dibasic amino acids excretion (Fig. 1A). Direct sequencing of entire coding region of SLC3A1 and SLC7A9 genes of the patient revealed both a G (normal) and A (mutant) at nucleotide 535 in exon 5, resulting in the presence of a Gly (codon GGA) at amino acid position 173 and a Arg (codon AGA) in heterozygote state (Fig. 1B).