No abstract

The neuronal ceroid lipofuscinoses represent a group of disorders characterized by neurodegeneration and intracellular accumulation of an auto-fluorescent lipopigment (ceroid lipofuscin). Together, they represent the most prevalent class of childhood neurodegenerative disease. The neuronal ceroid lipofuscinoses encompass several distinct biological entities that vary in age of onset, specific neurological phenotype, and rate of progression. In this review, we describe 9 major forms and present a classification scheme. Understanding the age of onset, clinical features, and natural history can inform rational diagnostics. Better knowledge the natural histories of these disorders is necessary to shed light on the underlying pathobiology and to develop new therapeutics.

The neuronal ceroid lipofuscinoses constitute one of many groups of rare childhood diseases for which disease-modifying treatments are non-existent. Disease-specific barriers to therapeutic success include incomplete understanding of disease pathophysiology and limitations of treatments that cannot adequately cross the blood-brain barrier to access the central nervous system. Therapeutic development in the neuronal ceroid lipofuscinoses shares many challenges with other rare diseases, such as incomplete understanding of natural history to inform trial design, need for alternatives to the randomized controlled clinical trial, requirement for more sensitive outcome measures to quantify disease, limited access to resources required to mount a clinical trial (including funding), and difficulties of recruiting a small sample to participation. Solutions to these barriers will require multicenter collaboration, partnership with patient organizations, training a new generation of researchers interested in rare diseases, and leveraging existing resources.

Objective:The primary objective of this research was to characterize the movement disorders associated with FOXG1 mutations.Methods:We identified patients with FOXG1 mutations who were referred to either a tertiary movement disorder clinic or tertiary epilepsy service and retrospectively reviewed medical records, clinical investigations, neuroimaging, and available video footage. We administered a telephone-based questionnaire regarding the functional impact of the movement disorders and perceived efficacy of treatment to the caregivers of one cohort of participants.Results:We identified 28 patients with FOXG1 mutations, of whom 6 had previously unreported mutations. A wide variety of movement disorders were identified, with dystonia, choreoathetosis, and orolingual/facial dyskinesias most commonly present. Ninety-three percent of patients had a mixed movement disorder phenotype. In contrast to the phenotype classically described with FOXG1 mutations, 4 patients with missense mutations had a milder phenotype, with independent ambulation, spoken language, and normocephaly. Hyperkinetic involuntary movements were a major clinical feature in these patients. Of the symptomatic treatments targeted to control abnormal involuntary movements, most did not emerge as clearly beneficial, although 4 patients had a caregiver-reported response to levodopa.Conclusions:Abnormal involuntary movements are a major feature of FOXG1 mutations. Our study delineates the spectrum of movement disorders and confirms an expanding clinical phenotype. Symptomatic treatment may be considered for severe or disabling cases, although further research regarding potential treatment strategies is necessary.