Clues to Zika Damage Might Lie in Cases of Twins
Since identical twins share one placenta while fraternal twins almost always have separate placentas, Dr. Zatz and other experts suggested
that the Zika virus may have penetrated one placenta and not the other.
When João Lucas and his twin sister were born in August 2015, their mother, Neide Maria
Ferreira da Silva, was unaware he had microcephaly or brain damage, she said.
Determining why one twin became infected in the womb while the other did not may illuminate how Zika crosses the placenta, how it enters the brain,
and whether any genetic mutations make a fetus more resistant or susceptible to Zika infection.
Ms. da Silva was especially alarmed by João Lucas’s seizures, which made him "get purple"
and look "like his eyes were going to jump out." Sometimes he became so agitated, he would scratch himself in the face, Ms. da Silva said.
It took a month before she brought João Lucas to the geneticist, who said "his brain, it wasn’t like ours," Ms. da Silva, 42, recalled.