Table 1.

Baseline characteristics of the 3 patients, before transplantation in cases 1 and 2

Patient characteristics	Case 1	Case 2	Case 3
Age, yr, at diagnosis	47	52	23
Gender	Male	Female	Male
Race	Caucasian	Lebanese	Lebanese
Comorbidities	Obesity, hypertension, atrial fibrillation	Graves disease	Obesity, atrial flutter
Urolithiasis	No	No	Yes
Family history of kidney disease	No	No	No
Creatinine at presentation, μmol/l	356	268	1020
Proteinuria, g/24 h	0.92	1.09	0.23
Microscopic hematuria	No	No	No
Native kidney biopsy	LM: 15/18 globally sclerosed glomeruli; tubular, epithelial and interstitial birefringent, brown crystal deposition with diffuse interstitial inflammation and fibrosis. IF: nondiagnostic EM: Needle-shaped crystals in some tubules	LM: 6 of 10 globally sclerosed glomeruli; golden brown, birefringent tubular crystals with associated diffuse interstitial fibrosis and inflammation. IF: nondiagnostic EM: nondiagnostic	LM: 5 of 17 globally sclerosed glomeruli; yellow- brown, birefringent tubular crystals with associated diffuse interstitial fibrosis. IF: nondiagnostic EM: nondiagnostic
Provisional diagnosis	APRT deficiency	Chronic interstitial nephritis	Oxalate nephropathy
Time from presentation to dialysis (modality)	2 mo (hemodialysis)	3 yr (peritoneal dialysis)	<1 wk (hemodialysis)
Time from native biopsy to APRT diagnosis	10 wk	6 yr	10 mo
Genetic testing	Not done	Homozygous c.188G>A (p.Gly63Asp)	Homozygous c.188G>A (p.Gly63Asp)
APRT enzyme activity, nmol/min per mg	0.1	0.11	0.09
Urine stone analysis	NA	NA	Organic material
Urine 2,8-DHA	28 mmol/mol	Not available	Not available
Urine biochemistry	Hypocitraturia	Hypocitraturia	Hyperoxaluria
Urine microscopy	Yes, but assessed only posttransplant		Birefringent crystals

APRT, adenine phosphoribosyltransferase; EM, electron microscopy; IF, immunofluorescence; LM, light microscopy; mo, month; NA, not applicable; wk, week; y, yr.

Normal APRT enzyme activity > 0.15 nmol/min per mg and spot urine 2,8-DHA <13 mmol/mol.