New study highlights importance of newborn screening for lethal genetic disorder

[NEWS 26 February 2013] Contrary to current belief, routine newborn screening improves the detection of the lethal form of congenital adrenal hyperplasia (CAH) in girls as well as boys, saving lives in both sexes, according to a unique study of CAH during the last 100 years. Babies are routinely screened for CAH in most developed countries, including Sweden. The study was published online in The Lancet Diabetes and Endocrinology.

"Until now it was believed that newborn boys with the severe salt-wasting form of CAH were at much greater risk of delayed diagnosis and early death than girls, as girls are more often diagnosed shortly after birth because of ambiguous genitalia", says senior researcher Anna Nordenström, Associate Professor at Karolinska Institutet and also a Pediatrician at Karolinska University Hospital, Huddinge. "However, our data show that both boys and girls are missed by physical examination, and that new-born screening improves survival in both sexes equally."

CAH is the most common adrenal disorder in children and affects the production of cortisol in the adrenal glands. The life-threatening salt-wasting form of CAH affects one in 10000 to 15000 live births and is associated with overproduction of androgen hormones, which can result in girls being born with ambiguous genitalia, while boys generally appear normal. It can lead to serious illness (neurological damage or intellectual disability) and death if not recognised and treated early enough.

In the current study, Dr Nordenström and her colleagues analysed all known cases of CAH in Sweden between 1910 and 2011, and examined the impact of medical developments over time. The analysis showed a dramatic increase in diagnosed cases in the 1960s and 1970s, following the discovery of the first effective treatment in 1950 and increased awareness of CAH and its symptoms, and after the introduction of newborn screening in 1986.

The proportion of severe cases (salt-wasting CAH) diagnosed increased significantly after the introduction of screening, and the female-to-male ratio in these patients was close to one. Around 16 percent of diagnosed patients born after the start of the screening programme were not identified by screening, but most of these (38/43 cases) were late-onset non-classical cases - a milder form that can appear any time from early childhood with rapid growth or other signs of increased androgen production -that were detected at a later date.

The study was supported by the Swedish Research Council, the Centre of Gender Medicine at Karolinska Institutet,

the Stockholm County Council, the Sällskapet Barnavård Foundation,the Stiftelsen Samariten Foundation, the Stiftelsen Frimurare Barnhuset Foundation, and the Novo Nordisk Foundation. Most part of this news article was originally sent as a press release by The Lancet Diabetes & Endocrinology.

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