A new mutation in the C-terminal end of TTC37 leading to a mild form of syndromic diarrhea/tricho-hepato-enteric syndrome in seven patients from two families

Syndromic diarrhea/tricho-hepato-enteric syndrome (SD/THE) is a rare congenital enteropathy with seven main clinical features: intractable diarrhea of infancy, hair abnormalities, intrauterine growth restriction (IUGR), facial dysmorphism, immune dysfunction, and liver and skin abnormalities. SD/THE is caused by mutations in TTC37 or SKIV2L, two genes encoding components of the human SKI complex. To date, approximately 50 SD/THE patients have been described with a wide spectrum of mutations, and only one recurrent mutation has been identified in independent families. We present a detailed description of seven patients of Turkish origin with the same new mutation in TTC37: c.4572 G>A p.(Trp1524X). All seven patients were homozygous for this mutation and presented the typical clinical features of SD/THE, but with a milder presentation than usual. All seven patients were alive at the last follow-up. Four out of seven patients had no IUGR, and four patients never required parenteral nutrition. All patients presented a better growth rate than previously described in patients with SD/THE, with 4/7 above the 3rd percentile. The mutation is localized only forty amino acids from the end of TTC37, and as TTC37 is longer than the yeast SKI3, it is possible that a truncated protein is expressed and plays a reduced role in the SKI complex.