A rare treatable cause for atypical frontotemporal dementia with multiple fractures in a young female

Frontal and temporal lobe involvement in young people is seen in infections like neurosyphilis, Vitamin B12 deficiency, NPH, tumors and neurometabolic disorders apart from neurodegenerative dementias. Involvement of other parts of neuraxis in addition to Fronto temporal features is a clue for the specific diagnosis. Cerebro tendinous xantamatosis (CTX) is a rare treatable inborn error of bile acid metabolism. Reported average delay from onset of symptoms to diagnosis is about 16 years as per reports. A patient responds very well to treatment, if diagnosed before significant neurological damage had occurred. 40 year old female had been symptomatic for 11 years with tendon xanthomas, severe osteopenia and multiple fractures. She presented to us with features of Frontal, temporal and cerebellar involvement. Frontal and temporal lobe dysfunction in neuropsychological tests with MRI showing frontal, temporal and cerebellar atrophy. Genetic testing with whole exome sequencing showed TREM2 (-) (ENST00000373113) Exon 2 c.377T>G (p.Val126Gly) Homozygous Autosomal recessive. Short stature, tendon xanthomas, cognitive behavioral impairment with severe osteopenia is consistent with the diagnosis of CTX. CTX is a relatively rare and treatable cause for atypical Fronto temporal dementia.