# Neurodevelopmental outcomes following hematopoietic cell transplantation for patients with severe combined immunodeficiency (SCID): A PIDTC study

## TL;DR

Children with SCID who undergo hematopoietic cell transplantation show average neurodevelopmental outcomes, with family income being a key factor affecting results.

## Contribution

The study provides the most comprehensive analysis of neurodevelopmental outcomes in SCID patients post-HCT.

## Key findings

- SCID subjects performed in the average range compared to the normative population.
- Family income below $50,000 was associated with poorer neurodevelopmental outcomes.
- Newborn screening, conditioning regimen, and genotype had no significant impact on outcomes.

## Abstract

We evaluated 69 subjects with SCID to assess the neurodevelopmental outcomes following HCT. Compared with the normative population, our subjects performed in the average range. There was no impact of newborn screening, conditioning, or genotype. Families earning <$50,000 had poorer outcomes. Our study provides the most substantial, comprehensive analysis of ND outcomes for SCID.

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for severe combined immunodeficiency (SCID). Since the initiation of newborn screening (NBS), survival rates have improved significantly, but the impact of HCT upon neurodevelopment for patients with SCID requires more investigation. We performed a cross-sectional study of subjects with SCID in North America to assess the impact of NBS, transplant conditioning regimen, and genotype on neurodevelopmental outcomes after HCT. 69 subjects with SCID from 17 PIDTC centers (excluding those with ADA deficiency), ages 6–16 years, received comprehensive standardized neurodevelopmental testing of cognitive, behavioral, and emotional function. Compared with the normative population, our subjects performed in the average range. We found no impact of NBS, chemotherapy conditioning, or genotype. Multivariate analysis revealed a significant decrease in IQ in subjects whose families earned <$50,000 per year. We recommend that children treated by HCT for SCID be monitored with periodic cognitive and behavioral assessments for deficits that could potentially impact long-term ND outcomes.