Advent of the NBS has led to the identification of asymptomatic infants found to have a positive NBS with at least one mutation and a SC concentration between 30 and 59 mmol/L, who are considered to have an inconclusive diagnosis and may be designated to have CF Screen Positive, Inconclusive Diagnosis (CFSPID), also known as CFTR-related metabolic syndrome (CRMS) (8–15). The gene discussed is CFTR; the disease is CFTR-related metabolic syndrome/CF screen positive, inconclusive diagnosis.