<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by Ohdo syndrome, Say-Barber-Biesecker-Young-Simpson variant ? [/INST] The SBBYS variant of Ohdo syndrome is estimated to occur in fewer than 1 per million people. At least 19 cases have been reported in the medical literature. </s>