Orphanet rare-disease nomenclature id Orphanet_163690 (Hypotonia - cystinuria syndrome) can be described as follows. Hypotonia-Cystinuria syndrome (HCS) is a rare syndrome including neonatal and infantile hypotonia and failure to thrive, cystinuria type 1 and nephrolithiasis, growth retardation due to growth hormone deficiency, and minor facial dysmorphism. Also known as: HCS.