Exome sequencing leads to correct diagnosis and life-saving treatment for mysterious genetic disorder

March 15, 2016

Other XIAP mutations have been linked to a rare but potentially fatal blood disease called hemophagocytic lymphohistiocytosis (HLH)??which can be successfully treated by bone marrow transplantation. Because the doctors considered their patient to be at high risk of developing HLH, they performed a hematopoietic progenitor cell transplant using unrelated donor cord blood as the blood stem cell source. Within a few weeks, the donor cells engrafted, providing the patient with normally functioning XIAP genes.

After recovering from the transplant procedure, the child was at last able to eat and drink normally, with no return of bowel disease. Doctors are confident that the transplant will prevent HLH??and hopeful that it will keep his inflammatory bowel disease from returning as well.The results demonstrate the power of exome sequencing to make diagnoses that would be practically impossible using conventional genetic tests. Although exome sequencing is very expensive, the cost is decreasing rapidly, while the knowledge needed to interpret the results continues to increase.

"The tools available to make this diagnosis have evolved so rapidly that they were not available when the child first presented 4 years ago," Dr. Jacob and colleagues write. They believe that, in the not-too-distant future, exome or even genome sequencing may even replace current single-gene test approaches. The authors emphasize that such approaches raise a host of new ethical considerations, including the need for careful informed consent.

Based on lessons learned from their experience, the team at the Human and Molecular Genetics Center are developing new strategies and policies to guide their approach to similar cases in the future. Dr. Jacob and co-authors conclude, "We are confident that genomic sequencing will have a growing role in establishing the correct diagnosis for patients and, most importantly, improving outcomes."

SOURCE Genetics in Medicine