[Analysis of a cerebrotendinous xanthomatosis case with mental retardation as the initial symptom].

Objective: To analyze a case of cerebrotendinous xanthomatosis (CTX) with mental retardation as the initial neurological symptom.

Methods: Medical imaging, histopathological assay and genetic testing were carried out to analyze the patient.

Results: Neurological manifestations of the 27-year-old male patient were initiated by mental retardation and subsequently memory lapses, ataxia, spastic paraplegia and fuzzy language. Other symptoms included cataract, xanthomatosis in Achilles tendon, kidney stones and high arches. The total bile acid in serum has risen to 14.7 umol/L. There were symmetrical abnormal signals in bilateral cerebellar dentate nuclei, hypointensities on T1WI and DWI and mixed signals on T2WI. Cholesterol crystallization and cholesterol granulomatous inflammation were found upon pathological examination of the Achilles tendon. The patient was found to have carried a compound heterozygous mutation of the CTX gene, which consisted of two novel mutations including c.379C>T (p.Arg127Trp) in exon 2 and c.1174G>A (p.Glu392Lys) in exon 6 of the CYP27A1 gene.

Conclusion: Clinicians should be alert to cerebrotendinous xanthomatosis when the patient has mental retardation caused by genetic and metabolic factors beginning at a young age, particularly accompanied with tendinous xanthomatosis and cataracts. CTX can be readily diagnosed by histopathological assay and sequencing of the CYP27A1 gene.