The phenotypic spectrum of ARX mutations.

Mutations in the ARX gene can result in many different phenotypes, including phenotypes associated with severe brain malformations and less severe phenotypes associated with syndromic or non-syndromic forms of XLMR. There seems to be a consistent genotype-phenotype correlation and both interfamilial and intrafamilial variability of expression of some of the mutations, particularly the common 428-451dup(24 bp) mutation. Familiarity with the phenotypic spectrum of ARX mutations is helpful in determining when to request ARX mutation analysis.