title: Ethnic and gender differences in rates of congenital adrenal hyperplasia in Western Australia over a 21 year period.
abstract: OBJECTIVE
  To evaluate the incidence, sex distribution, ethnicity, age at diagnosis, clinical presentation and morbidity of all childhood-onset congenital adrenal hyperplasia (CAH) cases in Western Australia (WA) between 1990 and 2010, a state where newborn screening for CAH is not in place.
  
  
  METHODS
  The total number of all known CAH cases was identified. Case files were reviewed retrospectively to determine clinical details. Classical CAH (C-CAH) was defined as patients presenting before 6 months of age and non-classical (NC-CAH) as presenting after 6 months.
  
  
  RESULTS
  Of the 41 CAH cases (26 female) born in WA, 5(12.2%) were of Aboriginal ethnicity. CAH was due to 21-hydroxylase deficiency in 40 cases. Of those with 21-hydroxylase deficiency, 37 were C-CAH (25 female) and 3 NC-CAH (all male). The incidence of C-CAH in WA was estimated to be 0.67 per 10, 000 live births (1:14, 869). The incidence rate ratio of Aboriginal compared with non-Aboriginal C-CAH was 2.45 (95% confidence interval 0.96-6.29). The mean age of diagnosis of C-CAH cases was lower in females (8.9 ± 2.5 days) compared to males (23.4 ± 9.8 days). Among these males, 72.7% presented initially with adrenal crisis.
  
  
  CONCLUSIONS
  The estimated incidence of classical CAH is similar to composite worldwide data. The increased female-to-male ratio is not in keeping with the expected sex distribution seen in a recessively inherited disease. The delayed diagnosis in males, with a significant proportion presenting with adrenal crisis, could be avoided with newborn screening. The higher rate of CAH in patients with Aboriginal ethnicity is a novel observation.
authors.affiliation: Department of Endocrinology, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Vinutha B
authors.initials: VB
authors.lastname: Shetty
authors.forename: Carol
authors.initials: C
authors.lastname: Bower
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Jones
authors.forename: Barry D
authors.initials: BD
authors.lastname: Lewis
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Davis
mesh_terms: D000293:Adolescent; D000312:Adrenal Hyperplasia, Congenital / Q000453:epidemiology / Q000208:ethnology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D012189:Retrospective Studies; D017678:Sex Distribution; D014904:Western Australia / Q000453:epidemiology; D055815:Young Adult