So far, SHPK deficiency has not been described in humans as an isolated defect and is only known as a combined defect, with cystinosis caused by a 57-kb deletion extending from exon 10 of CTNS (cystinosin, lysosomal cystine transporter), upstream through SHPK/CARKL, to intron 2 of TRPV1 (transient receptor potential vanilloid 1) (Touchman et al 2000; Freed et al 2011). The gene discussed is CTNS; the disease is cystinosis.