Cerebral folate transporter deficiency: a potentially treatable neurometabolic disorder

Cerebral folate deficiency (CFD) syndrome is a rare treatable neurometabolic disorder with low levels of the active form of folaten in cerebrospinal fluid (CSF) arising from different causes such as FOLR1 gene mutations or autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus. It is characterized by late infantile onset refractory seizures, ataxia, movement disorder, and unexplained global developmental delay. Here, we report a patient diagnosed with autistic spectrum disorder, followed by refractory myoclonic-atonic seizures, ataxia, and loss of motor skills over time. A homozygous missense (c.665A > G) mutation in FOLR1 gene and extremely low CSF 5-methyltetrahydrofolate level led to the diagnosis of CFD. Although she was initiated on combined oral and intravenous high doses of folinic acid treatment at 6 years of age, mild improvement was achieved in terms of epileptic seizures and motor skills. It is important that CFD should be kept in mind in cases with refractory myoclonic-atonic seizure and folinic acid treatment should be started as soon as possible.

Managing CLN2 disease: a treatable neurodegenerative condition among other treatable early childhood epilepsies

INTRODUCTION

Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a rare pediatric neurodegenerative condition, which is usually fatal by mid-adolescence. Seizures are one of the most common early symptoms of CLN2 disease, but patients often experience language deficits, movement disorders, and behavioral problems. Diagnosis of CLN2 disease is challenging (particularly when differentiating between early-onset developmental, metabolic, or epileptic syndromes), and diagnostic delays often overlap with rapid disease progression. An enzyme replacement therapy (cerliponase alfa) is now available, adding CLN2 disease to the list of potentially treatable disorders requiring a prompt diagnosis.

AREAS COVERED

Although advances in enzymatic activity testing and genetic testing have facilitated diagnoses of CLN2 disease, our review highlights the presenting symptoms that are vital in directing clinicians to perform appropriate tests or seek expert opinion. We also describe common diagnostic challenges and some potential misdiagnoses that may occur during differential diagnosis.

EXPERT OPINION

An awareness of CLN2 disease as a potentially treatable disorder and increased understanding of the key presenting symptoms can support selection of appropriate tests and prompt diagnosis. The available enzyme replacement therapy heralds an even greater imperative for early diagnosis, and for clinicians to direct patients to appropriate diagnostic pathways.

Neurological Complications of Nutritional Disease

Vitamins and minerals have essential functions in the body, from signal transduction to acting as cofactors for numerous enzymatic processes. Nutritional deficiencies and excess of certain vitamins and minerals can have profound effects on the central and peripheral nervous systems from early development into adulthood. This article summarizes the role of various nutritional factors in the nervous system and the neurological symptoms that can arise from deficiency or excess.

Treatable Inborn Errors of Metabolism Due to Membrane Vitamin Transporters Deficiency

B vitamins act as cofactors for strategic metabolic processes. The SLC19 gene family of solute carriers has a significant structural similarity, transporting substrates with different structure and ionic charge. Three proteins of this family are expressed ubiquitously and mediate the transport of 2 important water-soluble vitamins, folate, and thiamine. SLC19A1 transports folate and SLC19A2 and SLC19A3 transport thiamine. PCFT and FOLR1 ensure intestinal absorption and transport of folate through the blood-brain barrier and SLC19A25 transports thiamine into the mitochondria. Several damaging genetic defects in vitamin B transport and metabolism have been reported. The most relevant feature of thiamine and folate transport defects is that both of them are treatable disorders. In this article, we discuss the biology and transport of thiamine and folate, as well as the clinical phenotype of the genetic defects.