Clinical and neuroimaging features in a case of cerebrotendinous xanthomatosis with a CYP27A1 genotype newly identified in morocco: a literature review of African cases
摘要
Cerebrotendinous xanthomatosis (CTX; OMIM 213700) is a rare autosomal recessive neurometabolic disorder caused by pathogenic variants in CYP27A1 (OMIM 606530), encoding sterol 27-hydroxylase. Enzymatic deficiency impairs bile acid synthesis and leads to systemic accumulation of cholestanol and cholesterol, resulting in progressive multisystem involvement. Neurological manifestations often coexist with tendon xanthomas, cataracts, and normocholesterolemia, forming a characteristic clinical triad. Early treatment with chenodeoxycholic acid can prevent or reverse neurological decline, emphasizing the need for timely recognition and genetic confirmation. We report a 25-year-old Moroccan woman presenting with bilateral cataracts and progressive neurological deterioration from age 23, characterized by ataxia, intention tremor, and spasticity. Examination revealed Achilles tendon xanthomas, xanthelasma, and increased muscle tone. Biochemical analysis demonstrated elevated cholestanol levels, and brain MRI showed diffuse white matter hyperintensities. Genetic testing identified a homozygous splice donor site variant in CYP27A1 (NC_000002.11(NM_000784.4):c.446 + 1G > A), confirmed by parental segregation analysis. Comparison with three previously described patients carrying the same variant revealed consistent ocular and cerebellar involvement but notable variability in age at onset, neurological severity, and systemic features. Review of African CTX cases demonstrated presentations ranging from the typical triad (cataracts, tendon xanthomas, neurological decline) to milder or neuropsychiatric forms without xanthomas. North African cases often share founder genotypes and show severe neurological impairment, whereas sub-Saharan cases exhibit broader expressivity. These patterns suggest regional genetic influences and highlight ongoing diagnostic delays across Africa.