Table 3.

Clinical characteristics according to mutation group

General Features	Missense Mutations	Deletion/Duplication/Splice/Missense Mutations^a	P Value
No. of patients	34	61
Boys/girls, n	18/16	34/27	0.79
Age at diagnosis, median (IQR), yr	2 (1–8)	2 (1–3)	0.11
Age at the last follow-up visit, mean±SD, yr	13±7	10±6	0.10
Duration of follow-up, mean±SD, yr	8±7	7±6	0.51
Cysteamine dose, mean±SD, mg⋅kg^–1⋅d^–1	51.0±12.4	52.1±11.8	0.85
Age at onset of ESRD, mean±SD, yr	12±6	10±3	0.79
eGFR at last follow-up visit,^b mean±SD, yr	90±50	68±41	0.09
Leukocyte cystine level,^c median (IQR)	1.6 (1.6–3.6)	1.5 (0.6–4.1)	0.82
Systemic findings, n			0.51
Hypothyroidism	7	19
Rickets	13	21
Gastrointestinal involvement	2	4
RRT at the last follow-up visit (patient no.), n			0.95
Peritoneal dialysis	5	5
Hemodialysis	1	7
Transplantation	7	11

IQR, interquartile range.
↵a Three missense mutations (c.681G>A [p.Glu227Glu], c.664C>T [p.Gln222*], and c.G14A [p.Trp5*]).
↵b After exclusion of patients undergoing RRT.
↵c Nanomole half-cystine per milligram protein.