1. Introduction
Cerebrotendinous xanthomatosis (CTX) is a rare inherited disorder of lipid storage characterized by abnormal deposition of cholestanol and cholesterol in multiple tissues, particularly in the brain and tendons1. Mutations in CYP27A1 lead to a deficiency in sterol 27-hydroxylase 2. The deficiency of this enzyme prevents cholesterol being converted into bile acid chenodeoxycholic acid. The block in the synthesis of this bile acid creates the accumulation of bile acid pathway intermediates and cholestanol in the blood and tissues of the affected individuals. The balance between synthesis and catabolism of cholesterol should be tightly regulated to ensure normal cellular processes 3. Up to now, more than 400 cases have been reported worldwide 4. The clinical manifestations usually start at infancy and develop during the first and second decades of life 4. Patients with CTX demonstrate diverse manifestations with multi-organ involvement and an extensive range of neurological and non-neurological symptoms. The neurological features of CTX reported in the literature include pyramidal and cerebellar signs, sensory-motor peripheral neuropathy, intellectual disability, and dementia. Common non-neurological disorder include early-onset bilateral cataract in childhood, formation of tendon xanthomas (most often in the Achilles’ tendons), and diarrhea5,6. In addition, patients with CTX suffer from severe premature atherosclerosis, pulmonary involvement, and osteoporosis with repeated bone fractures 7. A diagnosis of CTX is made based on clinical findings, biochemical testing, neuroimaging, and molecular genetic analysis 8,9. This is the first report of a CTX patient with infertility due to azoospermia.