The team published the work today in the journal Nature Genetics.

“We study primate genomes to get a better understanding of the biology of the species that are most closely related to humans,” said Dr. Jeffrey Rogers, associate professor in the Human Genome Sequencing Center at Baylor and a lead author on the report. “The previous sequences of the great apes and macaques, which are very closely related to humans on the primate evolutionary tree, have provided remarkable new information about the evolutionary origins of the human genome and the processes involved.”

With the sequence of the marmoset, the team revealed for the first time the genome of a non-human primate in the New World monkeys, which represents a separate branch in the primate evolutionary tree that is more distant from humans than those whose genomes have been studied in detail before. The sequence allows researchers to broaden their ability to study the human genome and its history as revealed by comparison with other primates.

The sequencing was conducted jointly by Baylor and Washington University and led by Dr. Kim Worley, professor in the Human Genome Sequencing Center, and Rogers at Baylor, and Drs. Richard K. Wilson, director, and Wesley Warren of The Genome Institute at Washington University, in collaboration with Dr. Suzette Tardif of The University of Texas Health Science Center in San Antonio and the Southwest National Primate Research Center.

“Each new non-human primate genome adds to a deeper understanding of human biology,” said Dr. Richard Gibbs, director of the Human Genome Sequencing Center at Baylor and a principal investigator of the study.

Twinning

The study revealed unique genetic characteristics observed in the marmoset, including several genes that are likely responsible for their ability to consistently reproduce multiple births.

“Unlike humans, marmosets consistently give birth to twins without the association of any medical issues,” said Worley. “So why is it OK in marmosets but not in humans where it is considered high risk and associated with more complications?”

It turns out the marmoset gene WFIKKN1 exhibits changes associated with twinning in marmosets.

“From our analysis it appears that the gene may act as some kind of critical switch between multiples and singleton pregnancies, though it is not the only gene involved,” said Rogers, who added the finding could apply to studies of multiple pregnancies in humans.

The team was also looked for genetic changes associated with a unique trait found in marmosets and their close relatives, but not described in any other mammal. The dizygotic (or fraternal) twins in marmosets exchange blood stem cells called hematopoietic stem cells in utero, which leads to chimerism, a single organism composed of genetically distinct cells.