Mutations in the TRIM8 gene have been described in patients with severe 
developmental delay, intellectual disability and epilepsy. Only six patients 
have been described to date. All the previous mutations were truncating variants 
clustered in the C-terminus of the protein. A previous patient with 
TRIM8-related epileptic encephalopathy was reported to have nephrotic syndrome. 
Here we describe the clinical, radiological and histological features of an 
8-year-old male patient with a TRIM8 mutation who, in contrast to previous 
patients, had only mild intellectual disability and well-controlled epilepsy. 
The patient was found to have proteinuria at 2 years of age. Renal biopsy 
findings were suggestive of focal segmental glomerulosclerosis. His kidney 
function declined and peritoneal dialysis was started at 5 years of age. He 
underwent renal transplant at 7 years of age. Trio-based whole genome sequencing 
identified a novel de novo heterozygous frameshift mutation in TRIM8 
(NM_030912.2) c.1198_1220del, p.(Tyr400ArgfsTer2). This patient is further 
evidence that TRIM8 mutations cause a syndrome with both neurological and renal 
features. Our findings suggest the spectrum of TRIM8-related disease may be 
wider than previously thought with the possibility of milder neurodevelopmental 
problems and/or a more severe, progressive renal phenotype. We highlight the 
need for proteinuria screening in patients with TRIM8 mutations.