Clinical characteristics and mutation analysis of Chinese children with 17α-hydroxylase deficiency: a report on three cases.

BACKGROUND

17α-hydroxylase deficiency (17-OHD) is an uncommon type of congenital adrenal hyperplasia. It manifests as hypokalemia, hypertension, and hypergonadotropic hypogonadism and arises from a mutation in the CYP17A1 (cytochrome P450 17A1) gene. Diagnosis for children with 17-OHD remains challenging, and the means to arriving at a timely diagnosis are needed.

CASE DESCRIPTION: The patients in this case report were admitted to hospital for unusual growth velocity. Examinations revealed that their actual bone age was younger than their chronological age. However, their height was greater than the height predicted according to their bone age. This was speculated to be due to a lack of estrogen and subsequent delayed epiphyseal closure. Despite the delay in growth, it was determined that the patients would eventually grow to an above average, tall stature. Pelvic ultrasound or magnetic resonance imaging (MRI) revealed the absence of gonads in a patient with the 46,XY karyotype. Gene testing confirmed a novel variant and three reported variants in the CYP17A1 gene. All three patients carried p.D487_F489 deletion in exon 8, a variant common in the Chinese population.

CONCLUSIONS

For patients with an unusual growth velocity, absence of secondary sexual characteristics, hypertension, and hypokalemia, laboratory data, karyotyping, pelvic ultrasound or MRI, and bone age can be useful in arriving at a diagnosis of 17-OHD in a timely manner, with gene testing being recommended to confirm the diagnosis. An unusual growth velocity, with the actual height greater than that predicted by bone age, may be a useful indicator of 17-OHD, especially when it is difficult for clinical physicians to perform gene testing.