Two patients exhibited metabolic diseases: a boy with hypoglycemia carried a novel stop-gain variant (c.2331G > A, p.W777X) in ABCC8 that was associated with hypoglycemia in infancy [MIM:240800], and a girl with metabolic acidosis carried two LP variants, including one stop-gain variant (c.3853C > T, p.Q1285X) and one splicing variant (c.3303 + 1G > C) in OPLAH, that were associated with 5-oxoprolinase deficiency [MIM:260005]. The gene discussed is OPLAH; the disease is 5-oxoprolinase deficiency.