Fetuses with Down's syndrome express some genes differently than their normal counterparts, scientists have revealed. This discovery may pave the way for new methods to treat the condition in the womb.
Down's syndrome is caused when some or all of an extra copy of chromosome 21 is present.
However, scientists are still unaware of exactly how this additional set of genes disrupts development, leading to learning difficulties and other symptoms of Down's.
Diana Bianchi and her team at Tufts Medical Center in Boston have now sampled the amniotic fluid of foetuses with and without Down's and found 414 genes - many not on chromosome 21 - that are expressed differently in those with the disorder.
A large number of the identified genes signalled oxidative stress, which occurs when reactive oxygen products of metabolism damage cells.
Oxidative stress has already been linked with Down's syndrome in the past.
Bianchi has suggested that it could play a role in some of the symptoms of Down's, including abnormal brain growth, via these genes.
She concluded that finding drugs to alter the expression of these genes could allay the effects of oxidative stress, permitting the prenatal treatment of some Down's symptoms.
Roger Reeves, a physiologist at Johns Hopkins University in Baltimore, Maryland, has said that mitigating the effects of oxidative stress in the womb might be helpful.
However, he cautioned that it is likely to be just one of the contributing factors to the symptoms of Down's syndrome.
The study has been published in the Proceedings of the National Academy of Sciences.