TY - JOUR T1 - Prolidase deficiency in an infant with an incidental finding of methaemoglobinaemia JF - BMJ Case Reports JO - BMJ Case Reports DO - 10.1136/bcr-2021-244155 VL - 14 IS - 11 SP - e244155 AU - Chern Yan Tan AU - Easwari Kothandaraman AU - Arunabha Ghosh Y1 - 2021/11/01 UR - http://casereports.bmj.com/content/14/11/e244155.abstract N2 - A 4-week-old boy presented to the hospital with symptoms of diarrhoea and vomiting initially thought to be due to cow’s milk allergy. He was discharged with extensively hydrolysed formula. The patient represented with worsening of symptoms with metabolic acidosis and was screened and treated for sepsis. However, his condition deteriorated further and he developed methaemoglobinaemia. He was transferred to the high dependency unit and was given two doses of methylene blue. Further investigations were carried out, including rapid trio exome sequencing, which identified a homozygous pathogenic Peptidase D (PEPD) variant (c.978G>A, p.(Trp326*)). This was consistent with a diagnosis of prolidase deficiency. ER -