Death rates in the U.S. due to Krabbe disease and related leukodystrophy and lysosomal storage diseases

Leukodystrophies (LD) and lysosomal storage disorders (LSD) have generated increased interest recently as targets for newborn screening programs. Accurate epidemiological benchmarks are needed in the U.S. Age-specific mortality rates were estimated for Krabbe disease (KD) and nine related disorders. U.S. mortality records with E75.2 cause of death code during 1999-2004 were collected from 11 open record states. All E75.2 deaths in the United States were distributed into specific disease type based on proportions observed in these states. Yearly population sizes were obtained from the CDC and averaged. Mortality rates (per million individuals per year) by age group for the specific diseases were (for <5 or ≥5 years): Pelizaeus-Merzbacher (0.037/0.033); sudanophilic leukodystrophy (SLD) (0.037/0.004); Canavan (0.037/0.011), Alexander (0.147/0.022); Krabbe (0.994/0.007); metachromatic leukodystrophy (0.331/0.135); Fabry (0.000/0.124); Gaucher (0.221/0.073); Niemann-Pick (NP) (0.442/0.088); multiple sulfatase (0.000/0.004). This is the first report of mortality rates for the LD/LSD diseases in the U.S. Approximated birth prevalence rate for the early infantile Krabbe phenotype (onset 0-6 months) was based on the <5 year old mortality rate of one early infantile case per 244,000 births, which matches the 1 in 250,000 observed in the NYS newborn screening program as of 2011. It should be noted however that the NYS calculation refers only to the early infantile phenotype and does not include the majority of babies identified in the program with low GALC and two mutations who have remained clinically normal. It is presumed that most, if not all, will develop later onset forms of the disease, but this is by no means certain.