Trichohepatoenteric syndrome in a patient with TTC37 mutations – a case report

We report a patient with somatic retardation and woolly hair appearance who suffered from recurring episodes of watery mucous diarrhea, impaired liver functions, and failure to thrive. He manifested with severe infection courses, including hepatitis of unknown origin complicated by liver failure at 4 months, bronchopneumonia at 4 years, and life-threatening sepsis with septic shock at 8 years of age. Esophagogastroduodenoscopy and colonoscopy were performed at 4 years to rule out inflammatory bowel disease (IBD), and only signs of nonspecific colitis were evident. Immunology workup revealed slight reduction in CD4+ naive subsets and impaired T cell response to mitogens. Massive parallel sequencing (also termed next-generation sequencing – NGS) targeting a panel of primary immunodeficiency-related genes was used to examine the patient’s DNA. NGS analysis revealed two heterozygous variants in the TTC37 gene. Nonsense p.Arg1201* and missense p.Leu1505Ser variants in exons 34 and 42, respectively, were evaluated as pathogenic based on in silico predictions, their rare occurrence in the general population, and the fact that both mutations had already been described in patients with trichohepatoenteric syndrome (THES). As clinical features in our patient were in accordance with this diagnosis, we consider our findings as causative. THES could be a life-threatening condition, particularly in children who develop liver disease or severe infection courses. THES can have a similar clinical presentation as does very early-onset inflammatory bowel disease (VEO-IBD) and is often assigned to this group. Although IBD is generally regarded as a polygenic disease, some children with VEO-IBD are known also to have diseases with monogenic etiologies, as in THES. Targeted NGS is an efficient tool for establishing an accurate dia gnosis in VEO-IBD patients.