Clinical and molecular genetic features of cerebrotendinous xanthomatosis in Taiwan: Report of a novel CYP27A1 mutation and literature review

Background: Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disorder associated with mutations in the CYP27A1 gene, and the genetic features of CTX in Taiwanese have not been examined before.

Objectives: We report a new CTX family with a novel mutation in the CYP27A1 gene and analyze the clinical and molecular genetic features of CTX in Taiwan.

Methods: The clinical and molecular genetic features of the two siblings from the new CTX family and the other 7 reported Taiwanese CTX patients were included for analysis. The clinical features of the enrolled CTX patients were recorded using the indicators that make up the suspicion index (SI).

Results: The age at CTX diagnosis of the two siblings in the new CTX family were in late 30s, and predominantly psychiatric features. Both siblings had compound heterozygous splicing mutations in the CYP27A1 gene, including one mutation in exon 2 (c.435G>T, cryptic splice site) and one mutation in intron 7 (c.1264A>G, canonical splice site). None of the CTX patients in Taiwan were diagnosed during childhood or adolescence, and the most common clinical features of the 9 Taiwanese CTX patients were tendinous xanthomas, followed by ataxia and/or spastic paraparesis, dentate nuclei signal alternation at magnetic resonance imaging, intellectual disability and/or psychiatric disturbance, and polyneuropathy. Mutations in the CYP27A1 gene in the Taiwanese population were most commonly observed in exon 2, followed by exon 8 and intron 7. Except for one CTX patient who had an SI score of 100, the SI scores ranged from 300 to 400 before the study of the CYP27A1 gene and diagnosis.

Conclusions: We reported two Taiwanese CTX siblings who had compound heterozygous mutations in CYP27A1. Exons 2 and 8 and intron 7 are the hotspots for Taiwanese CTX mutations. The diagnosis of CTX in Taiwan is usually delayed and is probably under-recognized based on statistical estimations. Early identification and genetic diagnosis may be helpful to CTX patients because early treatment can reduce the accumulation of cholestanol and slow disease progression.