Role of genetic factors in recurrent miscarriages - A review

Recurrent miscarriage is classically defined as three or more consecutive pregnancy losses in about 1-5% of couples trying to conceive. However, several researchers have amended this to two or more because of the recent increase in childless miscarriages. Recurrent miscarriage is a clinical challenge for clinicians because there are many possible causes, and diagnostic testing is expensive and time-consuming. Established causes of recurrent miscarriage are antiphospholipid antibodies, uterine anomalies, and abnormal chromosomes in either partner, particularly translocations. Uterine anatomical abnormalities, endocrine abnormalities, infections, immunologic factors, environmental factors, metabolic or hormonal disorders, sperm quality, and maternal and paternal age have each been linked. Among them, the genetic factor plays a significant role in recurrent miscarriage. Approximately 70% of miscarriage conceptions with sporadic spontaneous miscarriage reveal some chromosome abnormality. Specifically, recurrent miscarriage can be caused by a structural or numerical defect in the parents' or fetus' chromosomes. Recurrent miscarriage has been linked to several genes, including those involved in oxidative stress, angiogenesis, clotting, and inflammation. Despite several well-known etiologic factors, the etiology of recurrent miscarriage is unknown in over half of all instances. The current review aims to analyse the role of the genetic basis of recurrent miscarriages.