Supplementary Material for: Screening for TSEN54 variant in Egyptian Patients with Ponto-Cerebellar Malformations.

Introduction: Pontocerebellar hypoplasia (PCH): represents a group of rare disorders with the mostly prenatal onset and time-dependent loss of brain parenchyma, predominantly affecting the cerebellum and pons with variable involvement of supratentorial structures. Radiologically and pathologically, they are characterized by small cerebellum and pons. Our study aimed to screen for the TSEN54 in Egyptian patients with PCH for proper counseling and to describe the brain MRI and the clinical phenotype and compare, them to those described in the literature.Methods: Thirty patients from thirty Egyptian families with a diagnosis of PCH based on neuroimaging findings were selected. Clinical evaluation, radiological findings, and genetic investigations were done for all patients. Results: The common missense variant c.919G>T (p.A307S) was identified in only six patients from six unrelated families (6/30; 20%) who showed different degrees of pontocerebellar malformations on brain imaging.Conclusion: The presence of a Dragonfly/butterfly-like pattern in the coronal section of the cerebellum recommends genetic testing of TSEN54 as a first step. For negative cases, whole exome sequencing (WES) is essential to reach a definite diagnosis and determine the etiology.