Serial MRI in a child with PEHO syndrome

Clinical and genetic features of PEHO and PEHO-Like syndromes: A scoping review

Progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO) syndrome is a genetic neurological condition characterized by extreme cerebellar atrophy. PEHO-Like syndrome is comparable to PEHO syndrome, with the exception that there is no typical neuro-radiologic or neuro-ophthalmic findings. PEHO spectrum disorders are highly clinically and genetically heterogeneous, and this has challenged their diagnosis. This scoping review aims to summarize and discuss common clinical and genetic features of these syndromes to help future researches. This study was performed according to a six-stage methodology structure and PRISMA guideline. A systematic search of seven databases was performed to find eligible publications prior to June 2020. Articles screening and data extraction were independently performed by two reviewers and quantitative and qualitative analyses were conducted. Thirty-eight articles were identified that fulfill the inclusion criteria. Cerebellar atrophy was the main clinical difference between the two groups but data on optic atrophy and infantile spasms/hypsarrhythmia were not consistent with the previously essential diagnostic criteria. Genetic analysis was performed in several studies, leading to identification of pathogenic variants in different genes that caused these conditions due to different mechanisms. Genetic studies could revolutionize the diagnosis process and our understanding of the etiology of this challenging group of patients by providing targeted sequencing panels and exome- or genome-scale studies in the future.

PEHO syndrome: the endpoint of different genetic epilepsies

Background

Progressive encephalopathy, hypsarrhythmia and optic atrophy (PEHO) has been described as a clinically distinct syndrome. It has been postulated that it is an autosomal recessive condition. However, the aetiology is poorly understood, and the genetic basis of the condition has not been fully elucidated. Our objective was to discover if PEHO syndrome is a single gene disorder.

Method

Children with PEHO and PEHO-like syndrome were recruited. Clinical, neurological and dysmorphic features were recorded; EEG reports and MRI scans were reviewed. Where possible, exome sequencing was carried out first to seek mutations in known early infantile developmental and epileptic encephalopathy (DEE) genes and then to use an agnostic approach to seek novel candidate genes. We sought intra–interfamilial phenotypic correlations and genotype–phenotype correlations when pathological mutations were identified.

Results

Twenty-three children were recruited from a diverse ethnic background, 19 of which were suitable for inclusion. They were similar in many of the core and the supporting features of PEHO, but there was significant variation in MRI and ophthalmological findings, even between siblings with the same mutation. A pathogenic genetic variant was identified in 15 of the 19 children. One further girl’s DNA failed analysis, but her two affected sisters shared confirmed variants. Pathogenic variants were identified in seven different genes.

Conclusions

We found significant clinical and genetic heterogeneity. Given the intrafamily variation demonstrated, we question whether the diagnostic criteria for MRI and ophthalmic findings should be altered. We also question whether PEHO and PEHO-like syndrome represent differing points on a clinical spectrum of the DEE. We conclude that PEHO and PEHO-like syndrome are clinically and genetically diverse entities—and are phenotypic endpoints of many severe genetic encephalopathies.