Genetic testing for cystic fibrosis, fragile X syndrome and spinal muscular atrophy is recommended for all would-be parents by a study in Australia.
The research is based on data from the Victorian Clinical Genetics Services (VCGS) which began to offer genetic testing in 2012 for these common and severe disorders.
Researchers anaylsed screenings of 12,000 individuals, and discovered that about 5 percent of them - 610 - were carriers of these diseases. This rate is on par with the population risk for Down's syndrome, and supports the stance that people should be routinely tested for these conditions, they said. Of the carriers, 88 percent had no family history and had no reason to suspect they were carrying these genetic disorders.
'There is also a misconception that these types of disorders are only relevant where there is a family history of the condition...but most parents who have a child with one of these disorders have no family history,' said senior author Professor David Amor, who is at the VCGS and Murdoch Children's Research Institute.
Genetic screening is typically done before pregnancy, but can be done during the first 12 weeks of gestation. Couples who are carriers of cystic fibrosis or spinal muscular atrophy have a 25 percent chance of having a baby with that disorder. Women who are carriers of the fragile X syndrome have a 50 percent change of passing on that mutation.
'It's important that all carriers are given the option of genetic counselling so they can discuss the implications of their results with an expert,' said Dr Alison Archibald at the VCGS, and joint first study-author.
Professor Amor added: 'Some couples will decide that [carrier screening] is not for them…but we know from experience that a lot of couples want this type of information.'
The study was published in Genetics in Medicine.