A series of Greek children with pure hereditary spastic paraplegia: clinical features and genetic findings.

Hereditary spastic paraplegia (HSP) is a clinically and genetically heterogeneous group of neurodegenerative disorders mainly characterized by progressive spasticity of the lower limbs. Adult case series dominate the literature, and there have been only a few studies in children. The purpose of this study is to describe our experience with pediatric HSP in Greece. We report the clinical and genetic findings in our patients and aim to offer insights into the diagnostic difficulties of childhood-onset disease. A series of 15 Greek children affected by pure HSP underwent extensive diagnostic investigations. Molecular analysis included whole exome sequencing (WES) or consecutive screening of candidate genes ATL1, SPAST, REEP1, and CYP7B1. WES performed in three cases yielded previously reported mutations in ATL1 and CYP7B1, and a variant c.397C>T of unknown significance in SPG7. Candidate gene screening performed in the remaining patients identified previously reported mutations in ATL1 (2), SPAST (2), and REEP1 (1), and two novel mutations, c.1636G>A and c.1413+3_6delAAGT, in SPAST. In six cases, the mutations were inherited from their parents, while in three cases, the mutations were apparently de novo. Our data confirm the genetic heterogeneity of childhood-onset pure HSP, with SPG4/SPAST and SPG3A/ATL1 being the most frequent forms. De novo occurrence of HSP does not seem to be uncommon. Candidate gene studies guided by diagnostic algorithms and WES seem both to be reasonable genetic testing strategies.

Trihexyphenidyl for acute life-threatening episodes due to a dystonic movement disorder in Rett syndrome.

In Rett syndrome (RS), acute life-threatening episodes (ALTEs) are usually attributed to epilepsy or autonomic dysfunction but they can represent a movement disorder (MD). We describe three girls with RS who experienced ALTEs from an early age. These were long considered epileptic until video-EEG in Patients 1 and 3 revealed their non-epileptic nature. A primary dystonic mechanism was suspected and Patients 1 and 2 were treated with Trihexyphenidyl with significantly reduced frequency of the ALTEs. Patient 3 died before Trihexyphenidyl was tried. Trihexyphenidyl in RS patients with similar presentations can modify the dystonia and prevent ALTEs.

Recurrent acute necrotizing encephalopathy following influenza A in a genetically predisposed family.

Acute necrotizing encephalopathy (ANE) typically affects young, healthy children who develop rapid-onset severe encephalopathy triggered by viral infections. This disease is more commonly reported in Japan but occurs worldwide, although it remains under-recognized in Western countries. An autosomal dominant form, ANE1, was recently identified. We report the details of a 9-year-old Caucasian female who experienced recurrent ANE episodes at the ages of 9 months and 9 years. Brain magnetic resonance imaging findings were characteristic of ANE during both episodes, although more extensive in the recent episode, which resulted in severe neurological sequelae; influenza A was identified on bronchoalveolar lavage during this episode. Interestingly, there was evidence of peripheral polyneuropathy during the recent episode, which has not previously been described in sporadic ANE. Both the patient and her mother, who had also had postviral polyneuritis in the past, harbour a mutation in Ran-binding protein 2 (RANBP2); this occurred de novo in the mother and confers genetic susceptibility to ANE. Our case suggests that recurrent disease and/or an expanded clinical phenotype raises the possibility of ANE1; positive family history, although supportive, is not necessary as the mutation can occur de novo. Increased awareness may lead to earlier recognition and better treatment options.

White matter abnormalities and dystonic motor disorder associated with mutations in the SLC16A2 gene.

AIM: Mutations in the SLC16A2 gene have been implicated in Allan-Herndon-Dudley syndrome (AHDS), an X-linked learning disability* syndrome associated with thyroid function test (TFT) abnormalities. Delayed myelination is a non-specific finding in individuals with learning disability whose genetic basis is often uncertain. The aim of this study was to describe neuroimaging findings and neurological features in males with SLC16A2 gene mutations. METHOD: We reviewed brain magnetic resonance imaging (MRI) findings and neurological features in a cohort of five males aged between 1 year 6 months and 6 years (median 4y) from four families harbouring SLC16A2 gene mutations. RESULTS: The participants presented aged between 4 and 9 months with initial hypotonia and subsequent spastic paraparesis with dystonic posturing and superimposed paroxysmal dyskinesias. Dystonic cerebral palsy was the most common initial clinical diagnosis, and AHDS was suspected only retrospectively, considering the characteristically abnormal thyroid function tests, with high serum tri-iodothyronine (T(3)), as the most consistent finding. Brain MRI showed absent or markedly delayed myelination in all five participants, prompting the suspicion of Pelizaeus-Merzbacher disease in one patient. INTERPRETATION: Our findings indicate a consistent association between defective neuronal T(3) uptake and delayed myelination. SLC16A2 involvement should be considered in males with learning disability, an associated motor or movement disorder, and evidence of delayed myelination on brain MRI. Although dysmorphic features suggestive of AHDS are not always present, T(3) measurement is a reliable screening test.

Infection-triggered familial or recurrent cases of acute necrotizing encephalopathy caused by mutations in a component of the nuclear pore, RANBP2.

Acute necrotizing encephalopathy (ANE) is a rapidly progressive encephalopathy that can occur in otherwise healthy children after common viral infections such as influenza and parainfluenza. Most ANE is sporadic and nonrecurrent (isolated ANE). However, we identified a 7 Mb interval containing a susceptibility locus (ANE1) in a family segregating recurrent ANE as an incompletely penetrant, autosomal-dominant trait. We now report that all affected individuals and obligate carriers in this family are heterozygous for a missense mutation (c.1880C-->T, p.Thr585Met) in the gene encoding the nuclear pore protein Ran Binding Protein 2 (RANBP2). To determine whether this mutation is the susceptibility allele, we screened controls and other patients with ANE who are unrelated to the index family. Patients from 9 of 15 additional kindreds with familial or recurrent ANE had the identical mutation. It arose de novo in two families and independently in several other families. Two other patients with familial ANE had different RANBP2 missense mutations that altered conserved residues. None of the three RANBP2 missense mutations were found in 19 patients with isolated ANE or in unaffected controls. We conclude that missense mutations in RANBP2 are susceptibility alleles for familial and recurrent cases of ANE.

A novel GLRA1 mutation in a recessive hyperekplexia pedigree.

We report the identification of a novel Y228C mutation within the M1 trans-membrane domain of the GLRA1 subunit of the glycine receptor responsible for a severe recessive hyperekplexia phenotype in a Kurdish pedigree.