Barth Syndrome with Late-Onset Cardiomyopathy: A Missed Opportunity for Diagnosis.

A male infant presented with neutropenia, growth delay, and death of a maternal uncle at age 2 years. Despite extensive evaluation over 10 years, Barth syndrome was not diagnosed until he presented in acute heart failure. Although late-onset cardiomyopathy is rare, persistence of common Barth features should have enabled earlier diagnosis.