dizygot

Dizygot is an adjective used to describe organisms or individuals that arise from two separate zygotes. In humans, the term most often refers to dizygotic twins, also known as fraternal twins, who result from fertilization of two different ova by two different sperm.

Genetically, dizygotic twins are no more alike than any two full siblings; they share about 50 percent of their DNA on average. They can be the same sex or opposite sex. Each twin typically has its own placenta and amniotic sac, producing a dichorionic diamniotic configuration, though placentas can fuse in rare cases.

Rates of dizygotic twinning vary by population and maternal factors. Dizygotic twinning occurs more often with advanced maternal age, a family history of twinning, and in certain ethnic groups; rates have risen with the use of assisted reproductive technologies and fertility drugs. Depending on population, about eight to fifteen in every thousand pregnancies result in dizygotic twins.

Prenatal diagnosis usually relies on ultrasound, which often reveals two fetuses and two placental structures. Dizygotic twinning carries higher obstetric risks than singleton pregnancies, including increased chances of preterm birth and low birth weight. Twin pregnancies require closer prenatal monitoring and planning for delivery, but many dizygotic twins are born healthy with appropriate care.

Etymology: dizygot derives from Greek elements meaning two and yoked or joined, reflecting the origin from two zygotes. Synonyms include dizygotic, fraternal twins, and two-zygote twinning.