Transforming Lives through Genetic Testing
In 2021, a 14-year-old young man was seen in the Metabolism Clinic at Riley Children’s Health following an inpatient stay for a blood clot in the heart. Labs identified a significant elevation of homocysteine, an amino acid that increases risk for blood clots when elevated. This can happen in several different metabolic conditions. Dr. Molly McPheron and the Metabolism Clinic team were tasked with identifying which condition could be causing the elevation.
Riley Children’s is the largest medical center in Indiana that treats children and adults with metabolic disorders, which are characterized by the body’s inability to appropriately utilize fat, carbohydrates, or protein in the foods we eat. While metabolic conditions cannot be cured, they can often be managed effectively with diet and/or medication.
His clinic visit was not this young man’s first trip to Riley. He was diagnosed with acute myelogenous leukemia (AML) shortly before his fifth birthday and was treated with chemotherapy. He relapsed a year later and required a hematopoietic stem cell transplant (HSCT). He was doing well following the transplant but was seen by Riley cardiologists for a dilated cardiomyopathy due to his chemotherapy.
With his complex medical history, whole exome sequencing was recommended to cast a wide net for any conditions that may be relevant. The history of AML and HSCT complicated the genetic work-up recommended by Dr. McPheron. Because of the stem cell transplant, the circulating blood cells do not have the patient’s DNA, but the DNA of his donor. The only way to accurately perform genetic testing was to perform a skin biopsy and grow the cells in culture in the cytogenetics lab.
In addition to issues with the source of DNA, the patient’s insurance denied the genetic testing. Given the impact a genetic diagnosis could have on directing treatment, the Riley team sought and received a grant from Riley Children’s Foundation. This prevented considerable financial strain for the family.
Testing provided a diagnosis of MTR-related methylcobalamin deficiency, cbIG type. Treatment includes high doses of vitamin B12 via daily injection and oral medications. Injections of this degree can be expensive as they must be ordered from a specialty pharmacy. Through the use of donor funds, the Riley team was able to expedite the start of treatment by two months.
The patient is now more than a year past his diagnosis, and he continues to do well. His homocysteine level has come down considerably and has had no further episodes of blood clots.