Alana Saarinen loves playing golf and the piano, listening to music and hanging out with friends. In those respects, she's like many teenagers around the world. Except she's not, because every cell in Alana's body isn't like mine and yours - Alana is one of a few people in the world who have DNA from three people.
"A lot of people say I have facial features from my mum, my eyes look like my dad… I have some traits from them and my personality is the same too," says Alana.
"I also have DNA from a third lady. But I wouldn't consider her a third parent, I just have some of her mitochondria."
Mitochondria are often called the cell's factories. They are the bits that create the energy all of our cells need to work, and keep the body functioning. But they also contain a little bit of DNA.
Alana Saarinen is one of only 30 to 50 people in the world who have some mitochondria, and therefore a bit of DNA, from a third person. She was conceived through a pioneering infertility treatment in the USA which was later banned.
But soon there could be more people like Alana, with three genetic parents, because the UK is looking to legalise a new, similar technique which would use a donor's mitochondria to try to eliminate debilitating genetic diseases. It is called mitochondrial replacement and if Parliament votes to let this happen, the UK would become the only country in the world to allow children with three people's DNA to be born.
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| The structure of a cell |
Nucleus: Where the majority of our DNA is held - this determines how we look and our personality
Mitochondria: Often described as the cell's factories, these create the energy to make the cell function
Cytoplasm: The jelly like substance that contains the nucleus and mitochondria
Alana was born through an infertility treatment called cytoplasmic transfer.
Her mum, Sharon Saarinen, had been trying to have a baby for 10 years through numerous IVF procedures.
"I felt worthless. I felt guilty that I couldn't give my husband a child. When you want a biological child but you can't have one, you're distraught. You can't sleep, it's 24-7, constantly on your mind," she says.
Cytoplasmic transfer was pioneered in the late 1990s by a clinical embryologist Dr Jacques Cohen and his team at the St Barnabus Institute in New Jersey, US.
"We felt that there was a chance that there was some element, some structure in the cytoplasm that didn't function optimally. One of the major candidates that could have been involved here are structures called mitochondria," he says.
Cohen transferred a bit of a donor woman's cytoplasm, containing mitochondria, to Sharon Saarinen's egg. It was then fertilised with her husband's sperm. As a little bit of mitochondria was transferred, some DNA from the donor was in the embryo.
Seventeen babies were born at Cohen's clinic, as a result of cytoplasmic transfer, who could have had DNA from three people.
But there was concern about some of the babies.
"There was one early miscarriage, considering there were twelve pregnancies that is an expected number," says Cohen.
He and his team believed that miscarriage occurred because the foetus was missing an X chromosome.
"Then there was another twin pregnancy, where one [of the twins] was considered entirely normal and the other had a missing X chromosome.
"So that's two out of the small group of foetuses that was obtained from this procedure. This did worry us and we reported that in the literature and in our ethical and review board that oversees these procedures," he says.
