A recent study (Gastroenterol 2014; 146: 1028-39) indicates that mutations in tetratricopeptide repeat domain 7A (TTC7A) can result in a severe form of very early onset inflammatory bowel disease (VEOIBD).
After identifying a TTC7A heterozygote mutation in an infant by using whole exome sequencing of DNA, the authors subsequently identified 4 additional patients (2 siblings from 2 families) who also had loss of function mutations in VEOIBD. Thus far, four of the five identified infants have died.
The manuscript has some terrific figures describing endoscopic/histologic characteristics, TTC7A genetic analysis, functional TTC7A enterocyte studies with immunofluorescence, impaired cell adhesion figure, tandem mass spectrometry, and a summary mechanistic figure (figure 6). Hematopoietic stem cell transplantation has not been effective and might not work due to the enterocyte defect.
This study adds another VEOIBD gene mutation. Previous mutations have involved in VEOIBD have included IL10RA/B, XIAP, ADAM17, NCF4, and NCF2/RAC2. The specific subtype matters as some defects may respond to stem cell transplantation.
Take-home message: there are a diverse number of pathways that can lead to VEOIBD. Given the recent availability of whole exome sequencing, more mutations are sure to be identified soon.
Related blog post/link:
IL-10 and early onset IBD | gutsandgrowth In addition to the Toronto group (noted in this blog), a group in Boston with Harland Winter/CJ Moran is also interested in whole exome sequencing for VEOIBD patients.
Causes and Treatment of Very-Early Onset IBD –-this link is to the AGA Journals blog post on the same subject.