Coexistence of SMA Type I with Citrate Transporter Deficiency Disorder - A Case Report

Background: The coexistence of spinal muscular atrophy (SMA) with other diseases has been rarely described. We report a unique case with dual pathogenic gene mutations: SMN1 gene causing SMA and SLC13A5 gene causing citrate transporter deficiency induced epilepsy (EIEE 25, OMIM 615905). Case presentation: The girl presented with recurrent focal seizures with semiology of eyelid blinking, deviation of eyes and facial twitches, which started from the second day of her life. Interictal EEG showed bilateral multifocal and generalized discharges. Brain MRI revealed delayed myelination and generalized volume loss. PET scan showed diffuse cortical hypometabolism. She had refractory seizures, including two episodes of status epilepticus while being treated with various antiseizure medications. Genetic analysis revealed homozygous deletion of SLC13A5 gene at 17p13.1. At one year of age, progressive hypotonia, initially ascribed to seizures and antiseizure medications, appearance of tongue fasciculations and need for respiratory support, prompted testing for SMA. Mutation at SMN1 gene locus (5q11.2-13.2) was found and SMA type I diagnosis was established. EMG/NCV revealed a motor neuron disorder. She was started on nusinersen at the age of 2.5 years, once it became available. She was tracheostomized for Bi Pap support. At the age of 4.5 years, she had a cardiac arrest and passed away. Conclusion: This is a case report of co-existent mutations in the SMN1 and SCL13A5 genes with overlapping and diagnostically confusing features of progressive hypotonia. The constellation of these separate genetic entities constitutes a clinical phenotype that has not been reported previously.