This paper studied the relationship between the gene that codes for protein 5-hydroxytryptamine (serotonin) receptor 3C (HTR3C) and the risks of chemotherapy. 

Chemotherapy is used in the treatment of breast cancer. However, chemotherapy can cause symptoms like fatigue and nausea that can affect one's quality of life. Evidence indicates that genes can determine the risk of developing chemotherapy-related symptoms. Different forms of the gene that codes for 5-hydroxytryptamine (serotonin) receptor 3C (HTR3C) have been associated with nausea in pregnancy and vomiting after chemotherapy.

The author studied the relationship between different forms of HTR3C and chemotherapy in patients with early breast cancer (stage II and III). 

Female patients who received a chemotherapy regimen involving doxorubicin (Adriamycin) and cyclophosphamide (Endoxan, Cytoxan) were analysed. Symptoms experienced by the patients were measured by a scale that assesses 32 physical and psychological symptoms, including but not limited to pain, nausea, feeling drowsy, shortness of breath, feeling irritable, hair loss, change in food tastes, sweats and worrying. A higher score indicated more and a greater intensity of symptoms. The patients' DNA was also studied to determine their genetic form of HTR3C. There are many different variants of the gene for HTR3C.

Among the variants, there was no association between variation CGH1 or COMT and the symptom assessment scale score. There was a significant association between the presence of K163 and G405 variants. These variants were associated with an increased symptom assessment scale score, with greater severity of symptoms. Additionally, the presence of NN, NK and KK variants were associated with specific symptoms. 

The authors concluded that there is an association between variants of the gene for HTR3C and severity of symptoms caused by chemotherapy. 

Talk to your doctor about your genetic risk for symptoms caused by chemotherapy.