Story of Seven-Year-Old John

Seven-year-old John was referred to a doctor with severe deficiency of red blood cells, white blood cells, and platelets. Clinical examination revealed bone marrow failure while Cytogenetic stress test confirmed that it was due to DNA damage.

Genetic testing at MedGenome Labs in Bangalore revealed a mutation (a disease causing change) in a gene called FANCG that is responsible for DNA repair. It was also observed that in John, both the copies of this gene had the mutation. He had no normal copy of FANCG gene to repair his damaged DNA. He was diagnosed with Fanconi Anemia.

Fanconi anemia is a rare genetic disease that mainly affects the bone marrow resulting in decreased production of all types of blood cells. The condition is most often diagnosed in children between 2 and 15 years old. Due to the abnormal gene the cells cannot repair their damaged DNA. It is an inherited disorder, where in both the both copies of the gene need to be faulty for disease to manifest itself. It is known as an autosomal recessive genetic disorder with 25% risk of recurrence in every pregnancy. Thus to inherit Fanconi anemia, a person must get 1 copy of the abnormal gene from each parent. When his parents were tested, it was found that they were carriers for this disease that is, one copy of FANCG gene was mutated. A carrier is a normal healthy individual who has one copy of a disease causing mutation. His maternal grandfather, paternal grandmother and paternal aunt were also found to be carriers on further investigation.

In the United States the carrier frequency or heterozygote frequency for Fanconi anemia is 1:181 whereas in Israel it is 1:93. Though there is no such data available in the Indian population, the number of patients or families with Fanconi anemia in India is rather high. This could be due to a relatively high degree of consanguineous marriages, especially in South India. One study from Mumbai revealed a significantly high frequency (36.4%) of parental consanguinity in Fanconi anemia patients compared to controls (3.33%) in our country.

Once Dr.Jadhav came to know that an abnormal gene was the cause of Master John’s condition, he realised that Anti-Thymocyte Globulin (ATG) therapy will not help this boy. The only cure then is a bone marrow transplant, and that too with a reduced intensity conditioning chemotherapy regimen, since patients with Fanconi anaemia cannot tolerate the usual doses of chemotherapy. Also, by testing the family members, he realized that almost everyone in the family was a carrier, and hence he needs to look for an unrelated donor. Master John is currently stable and an allogeneic Bone Marrow Transplant is being planned.

Summary

• Genetic testing helped in identifying mutation in FANCG gene
• Testing family helped in understanding the inheritance pattern and choosing the right treatment, Bone marrow transplant.

MedGenome is a leading solution provider of clinical genomics which offers genetic testing across various disease areas like neurology, oncology, cardiology, rare inherited diseases, endocrinology, hematology, pre natal, population genomics etc. MedGenome's diagnostics tests include many breakthroughs for genetic diagnostics including liquid biopsy, non-invasive prenatal screening test (NIPT), carrier screening, and whole exome sequencing for cost-effective identification of rare mutations at its CAP certified lab in Bangalore.

Medgenome offers	Sample requirements	Required forms	TAT
Fanconi anemia gene panel			Regular 21 days
Lynch Syndrome/ HNPCC gene panel		Test requisition form along with relevant clinical information including pedigree. consanguinity. age of onset, clinical presentation and symptoms
Clinical exome – 26MB (80-100x)			Regular 28 days