Incidence of classical 21-hydroxylase deficiency and distribution of CYP21A2 mutations in Estonia.
OBJECTIVE
To determine the incidence of classical 21-hydroxylase deficiency (21-OHD) in Estonia from 1978 to 2004, and describe their phenotype and genotype.


METHODS
All Estonian endocrinologists informed us about their patients with 21-OHD. The diagnosis was confirmed in 20 patients, who were all screened for 8 common mutations of the CYP21A2 gene.


RESULTS
The 27-year period incidence was 1:25,500. The incidence from 1992 was 1:16,100, which more accurately reflects the real situation in Estonia. The salt-wasting form (SW) was diagnosed in 14 (7 males) and the simple virilizing form in 6 patients (1 male). The median age at diagnosis of the SW form was 30 days in males and 2 days in females. The investigation of 34 unrelated alleles showed that a common deletion/conversion was the most frequent mutation in our group (7/34). Six other mutations were present: p.Ile172Asn (5/34), 8-bp deletion (3/34), intron-2 splice mutation (3/34), p.Arg356Trp (3/34), p.Gln318X (3/34) and a small conversion (2/34). Mutations in 8 alleles remained uncertain.


CONCLUSIONS
The incidence of classical 21-OHD in Estonia in 1992-2004 was 1:16,100. The genotype of our patients is similar to those from other Caucasian populations. The relatively late age at diagnosis and the skewed female:male ratio supports the need for newborn screening for 21-OHD.
Liivak
Kaur
K
Department of Paediatrics, University of Tartu, Tartu, Estonia.
Tobi
Simon
S
Schlecht
Helene
H
Tillmann
Vallo
V
D000312:Adrenal Hyperplasia, Congenital / Q000453:epidemiology / Q000209:etiology; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D004957:Estonia / Q000453:epidemiology; D005260:Female; D005838:Genotype; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008661:Metabolism, Inborn Errors / Q000150:complications / Q000453:epidemiology* / Q000235:genetics*; D015997:Neonatal Screening; D010641:Phenotype; D012744:Sex Ratio; D013255:Steroid 21-Hydroxylase / Q000235:genetics* / Q000378:metabolism*; D044465:White People / Q000235:genetics
D013255:Steroid 21-Hydroxylase