ESPE Yearbook of Paediatric Endocrinology

Brief summary: This paper reviews the incidence of congenital adrenal hyperplasia (CAH) across 58 studies (31 countries). The overall CAH incidence was 1:9498. Geographic variation was observed with a higher incidence in Eastern Mediterranean and South-East Asia and a lower incidence in countries of the Western Pacific region.

Untreated CAH is a recessive condition associated with high mortality and morbidity and early diagnosis and management are key. Unfortunately, neonatal CAH screening often remains limited to high income countries and access to affordable, lifesaving medicines (hydrocortisone and fludrocortisone) is poor in many low and middle income countries (LMICs) (www.clanchildhealth.org/mates4kids.html). One of the basic areas of research is simply to map the incidence of this condition.

These authors identified 58 published studies on CAH incidence. Several interesting aspects are emerging. First, CAH incidence tends to be higher in the Middle East, a region associated with a high degree of consanguinity, and in Southeast Asia, making these countries prime targets for resource allocation. Second, the authors were unable to find CAH data from large population studies for sub-Saharan Africa where neonatal screening is not routinely performed. Based on North American data, the incidence is assumed to be lower in Sub Saharan Africans compared to Whites, Hispanics and Asians, but this extrapolation is clearly unsatisfactory. Third, they found a high incidence of 1:6084 in China, based on a respectable number of tests (n=2 834 792). However, a subsequent even larger Chinese study reported a much lower incidence (1:23 024), based on 7.85 million tests in 41 different regions (1).

Overall, these data raise important points. First, neonatal screening should use identical diagnostic criteria across counties. This lack of standardization makes it very difficult to identify priority regions. Second, besides the lack of resources, other reasons why CAH screening is difficult to establish in LMICs are the lack of education of families on the importance of participating in screening, and lack of infrastructure making collection, transportation and sample analysis within an appropriate timeframe difficult. Finally, the present algorithm for CAH screening, based on 17OHP determination followed by liquid chromatography tandem mass spectrometry (LC–MS/MS) is cumbersome and costly. New approaches, such as genetic analysis (2) or point of care testing are needed to spearhead the development of reliable screening.

References: 1. Li Z, Huang L, Du C, Zhang C, Zhang M, Liang Y, Luo X. Analysis of the screening results for congenital adrenal hyperplasia involving 7.85 million newborns in China: A systematic review and meta-analysis. Front Endocrinol (Lausanne) 2021 Apr 23;12:624507. DOI: 10.3389/fendo.2021.624507. 2. Tippabathani J, Seenappa V, Murugan A, Phani NM, Hampe MH, Appaswamy G, Sadashiv Gambhir P. Neonatal screening for congenital adrenal hyperplasia in Indian newborns with reflex genetic analysis of 21-hydroxylase deficiency. Int J Neonatal Screen 2023; 9, 9: 1–7. DOI: 10.3390/ijns9010009.