Letter re: Acute intermittent porphyria-related leukoencephalopathy

We read with interest the article by Kevelam et al.1 Current neurogenetic knowledge continues to grow with new genotypes associated with classical clinical syndromes and new phenotypes associated with shocking genetic and metabolic mechanisms, especially in inherited neurometabolic disorders and leukodystrophies. The authors defined a new clinical spectrum of neurologic phenotypes associated with mutations in the HMBS gene,1 which can be summarized as follows: (1) autosomal dominant acute intermittent porphyria2; (2) autosomal recessive severe encephalopathy with early childhood fatality3; (3) autosomal recessive early-onset leukodystrophy with spastic ataxia and optic atrophy.1