Two-tiered newborn screening for infantile Krabbe disease allows timely treatment initiation and avoids false-positive results.

Abstract

Infantile Krabbe disease (IKD) is a severe, progressive neurological disorder that was recently added to the Recommended Uniform Screening Panel in the United States. IKD is a critical condition that requires a hematopoietic stem cell transplant, preferably by 30 days of age. This study examines whether the 2-tier newborn screening (NBS) strategy (psychosine [PSY] analysis when enzyme activity is low) causes clinically relevant delays compared with PSY measured at a first clinical follow-up visit. We reviewed the PSY analyses performed over a 6-year period on dried blood spots on infants < 28 days old. Results were sorted by the ordering site and final diagnosis. On average, infants with a positive NBS for IKD that included abnormal PSY received their diagnosis 7 days sooner than whose PSY testing was initiated during follow-up. Hematopoietic stem cell transplant occurred by the 36th day of life, on average, for cases with IKD detected by 2-tiered NBS. Effective NBS for Krabbe disease requires the use of PSY as a second-tier test, allowing for timely initiation of treatment while virtually eliminating false-positive results. PSY should be included in NBS algorithms for Krabbe disease, and timeliness metrics need to be adjusted.