PRPS1 and Alstrom syndrome: A total of 27/30 cases were solved for this cohort (detection rate:90%), including twenty patients with Usher type 2A syndrome and one Usher type 2C syndrome (ADGRV1). Other syndromic diagnoses in this cohort were Bardet-Biedl syndrome (2 cases; BBS5 and ARL6), Alstrom syndrome (1 case; ALMS1), Mucopolysaccharidosis type IIIC/ Sanfilippo C (1 case; HGSNAT), Arts syndrome (1 case, PRPS1), and Wolfram-like syndrome (1 case; WFS1).