Natural history of neurological abnormalities in cerebrotendinous xanthomatosis.

OBJECTIVES: Cerebrotendinous xanthomatosis (CTX) is a rare inherited neurodegenerative disorder in bile acid synthesis. The natural history of neurological abnormalities in CTX is not well understood. The object of this study was to determine neurological progression in CTX. METHODS: A literature search on PubMed for "cerebrotendinous xanthomatosis" yielded 91 publications that reported cases of CTX patients. Two independent reviewers abstracted information about the presence and age of onset of neurological abnormalities in published CTX cases. For each neurological abnormality, we estimated the probability of its onset at any given age using cumulative incidence function analysis. We also present our own case series, in which five CTX patients were evaluated. RESULTS: The literature search yielded 194 CTX cases (ages ranging from newborn to 67 years old). The most common neurological abnormalities were corticospinal tract abnormalities including weakness, hyperreflexia, spasticity, Babinski sign (59.8%), ataxia (58.8%), cognitive decline (46.4%), and gait difficulty (38.1%); 68 (35.0%) had baseline cognitive problems. Cumulative incidence function analysis revealed that ataxia, gait difficulties, and corticospinal tract abnormalities developed throughout life, while cognitive decline tended to develop later in life. Of the less common neurological abnormalities, seizures, psychiatric changes and speech changes developed throughout life, while parkinsonism and sensory changes tended to develop later in life. Our case series corroborated this temporal pattern of neurological abnormalities. CONCLUSION: We provide estimates for the neurological progression of CTX, categorizing neurological abnormalities according to time and probability of development. Our approach may be applicable to other rare disorders.

Randomized trial of l-serine in patients with hereditary sensory and autonomic neuropathy type 1.

OBJECTIVE: To evaluate the safety and efficacy of l-serine in humans with hereditary sensory autonomic neuropathy type I (HSAN1). METHODS: In this randomized, placebo-controlled, parallel-group trial with open-label extension, patients aged 18-70 years with symptomatic HSAN1 were randomized to l-serine (400 mg/kg/day) or placebo for 1 year. All participants received l-serine during the second year. The primary outcome measure was the Charcot-Marie-Tooth Neuropathy Score version 2 (CMTNS). Secondary outcomes included plasma sphingolipid levels, epidermal nerve fiber density, electrophysiologic measurements, patient-reported measures, and adverse events. RESULTS: Between August 2013 and April 2014, we enrolled and randomized 18 participants, 16 of whom completed the study. After 1 year, the l-serine group experienced improvement in CMTNS relative to the placebo group (-1.5 units, 95% CI -2.8 to -0.1, p = 0.03), with evidence of continued improvement in the second year of treatment (-0.77, 95% CI -1.67 to 0.13, p = 0.09). Concomitantly, deoxysphinganine levels dropped in l-serine-treated but not placebo-treated participants (59% decrease vs 11% increase; p < 0.001). There were no serious adverse effects related to l-serine. CONCLUSION: High-dose oral l-serine supplementation appears safe in patients with HSAN1 and is potentially effective at slowing disease progression. CLINICALTRIALSGOV IDENTIFIER: NCT01733407. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that high-dose oral l-serine supplementation significantly slows disease progression in patients with HSAN1.