Arginine:glycine amidinotransferase (AGAT) deficiency: Clinical features and long term outcomes in 16 patients diagnosed worldwide

Abstract Background Arginine:glycine aminotransferase (AGAT) (GATM) deficiency is an autosomal recessive inborn error of creative synthesis. Objective We performed an international survey among physicians known to treat patients with AGAT deficiency, to assess clinical characteristics and long-term outcomes of this ultra-rare condition. Results 16 patients from 8 families of 8 different ethnic backgrounds were included. 1 patient was asymptomatic when diagnosed at age 3 weeks. 15 patients diagnosed between 16 months and 25 years of life had intellectual disability/developmental delay (IDD). 8 patients also had myopathy/proximal muscle weakness. Common biochemical denominators were low/undetectable guanidinoacetate (GAA) concentrations in urine and plasma, and low/undetectable cerebral creatine levels. 3 families had protein truncation/null mutations. The rest had missense and splice mutations. Treatment with creatine monohydrate (100–800 mg/kg/day) resulted in almost complete restoration of brain creatine levels and significant improvement of myopathy. The 2 patients treated since age 4 and 16 months had normal cognitive and behavioral development at age 10 and 11 years. Late treated patients had limited improvement of cognitive functions. Conclusion AGAT deficiency is a treatable intellectual disability. Early diagnosis may prevent IDD and myopathy. Patients with unexplained IDD with and without myopathy should be assessed for AGAT deficiency by determination of urine/plasma GAA and cerebral creatine levels (via brain MRS), and by GATM gene sequencing

Cognitive impairment in clinically isolated syndromes: A control-case study

Introduction - Cognitive impairment is common in multiple sclerosis (MS) but its diagnosis is often made late, at the stage of social and professional disinsertion. Studies of the cognitive aspects in early forms of MS such as clinically isolated syndrome (CIS) and radiologically isolated syndrome (RIS) are rare.Objectives - To analysis the cognitive functions of a first demyelinating event and identify the areas that would be most affected early.                            Patients and methods - The cognitive profile of a homogeneous population of 13 patients with a CIS was evaluated, and compared with 15 healthy controls, matched according to age, sex and level of education. A battery of neuropsychological tests (BCCogSEP, Short battery for cognitive assessment of MS) validated in MS,was used. Its components explore memory and verbal skills, attention, information processing speed (IPS) and executive functions.Results - The overall cognitive performance was reduced in the CIS group,compared to control group. Five out of thirteen CIS patients (38%) had an overall cognitive impairment, demonstrated by the achievement of at least two or three battery tests. The Paced Auditory Serial Addition Test (PASAT) was the most altered test (84.6% impairment). IPS and working memory were the most affected functions in the patients.Conclusion - Cognitive dysfunctions can be seen very early and can severely affect the prognosis of MS

Nerve Biopsy Is Still Useful in Some Inherited Neuropathies

International audienceIn hereditary neuropathies, next-generation sequencing techniques are producing a vast number of candidate gene mutations that need to be verified or excluded by careful genotype-phenotype correlation analysis. In most cases, clinical acumen is still important but needs to be combined with data from nerve conduction studies and, in some cases, from nerve biopsy examinations. Indeed, characteristic clinical, electrophysiological, and sometimes pathological features may be suggestive of a particular subtype of Charcot-Marie-Tooth (CMT) disease. Microscopical (mainly ultrastructural) human nerve biopsy patterns may be related to CMT diseases and gene defects. Even today, it is important to recognize these characteristic lesions in the context of a chronic idiopathic neuropathy as they may help search for or reveal a sporadic form of CMT. In practice, these different types of lesions are often linked to the known function of the mutated genes. Only a few patients diagnosed or suspected as having a CMT disease need a nerve biopsy that can help find or confirm the causative gene mutation. The indication for this procedure should be based on a case-by-case discussion

A TOR1AIP1 variant segregating with an early onset limb girdle myasthenia—Support for the role of LAP1 in NMJ function and disease

International audienceRare pathogenic variants in TOR1AIP1 (OMIM 614512), coding the inner nuclear membrane protein lamin-associated protein 1 (LAP1), have been associated with a spectrum of disorders including limb girdle muscular dystrophy with cardiac involvement and a severe multisystem phenotype. Recently, Cossins et al reported two siblings with limb girdle muscular dystrophy and impaired transmission of the neuromuscular synapse, demonstrating that defective LAP1 may lead to a congenital myasthenic syndrome. Herein, we describe the association of TOR1AIP1 deficiency with congenital myasthenic syndrome in three siblings