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Open access

Jasmeet Kaur, Alan M Rice, Elizabeth O’Connor, Anil Piya, Bradley Buckler and Himangshu S Bose

Congenital adrenal hyperplasia (CAH) is caused by mutations in cytochrome P450 side chain cleavage enzyme (CYP11A1 and old name, SCC). Errors in cholesterol side chain cleavage by the mitochondrial resident CYP11A1 results in an inadequate amount of pregnenolone production. This study was performed to evaluate the cause of salt-losing crisis and possible adrenal failure in a pediatric patient whose mother had a history of two previous stillbirths and loss of another baby within a week of birth. CAH can appear in any population in any region of the world. The study was conducted at Memorial University Medical Center and Mercer University School of Medicine. The patient was admitted to Pediatric Endocrinology Clinic due to salt-losing crisis and possible adrenal failure. The patient had CAH, an autosomal recessive disease, due to a novel mutation in exon 5 of the CYP11A1 gene, which generated a truncated protein of 286 amino acids compared with wild-type protein that has 521 amino acids (W286X). Although unrelated, both parents are carriers. Mitochondrial protein import analysis of the mutant CYP11A1 in steroidogenic MA-10 cells showed that the protein is imported in a similar fashion as observed for the wild-type protein and was cleaved to a shorter fragment. However, mutant’s activity was 10% of that obtained for the wild-type protein in non-steroidogenic COS-1 cells. In a patient of Mexican descent, a homozygous CYP11A1 mutation caused CAH, suggesting that this disease is not geographically restricted even in a homogeneous population.

Learning points:

  • Novel mutation in CYP11A1 causes CAH;

  • This is a pure population from Central Mexico;

  • Novel mutation created early truncated protein.

Open access

N Amin, N S Alvi, J H Barth, H P Field, E Finlay, K Tyerman, S Frazer, G Savill, N P Wright, T Makaya and T Mushtaq

Summary

Type 1 pseudohypoaldosteronism (PHA) is a rare heterogeneous group of disorders characterised by resistance to aldosterone action. There is resultant salt wasting in the neonatal period, with hyperkalaemia and metabolic acidosis. Only after results confirm isolated resistance to aldosterone can the diagnosis of type 1 PHA be confidently made. Type 1 PHA can be further classified into i) renal type 1 (autosomal dominant (AD)) and ii) multiple target organ defect/systemic type 1 (autosomal recessive (AR)). The aim of this case series was to characterise the mode of presentation, management and short-term clinical outcomes of patients with PHA type 1. Case notes of newly diagnosed infants presenting with PHA type 1 were reviewed over a 5-year time period. Seven patients were diagnosed with PHA type 1. Initial presentation ranged from 4 to 28 days of age. Six had weight loss as a presenting feature. All subjects had hyperkalaemia, hyponatraemia, with elevated renin and aldosterone levels. Five patients have renal PHA type 1 and two patients have systemic PHA type, of whom one has had genetic testing to confirm the AR gene mutation on the SCNN1A gene. Renal PHA type 1 responds well to salt supplementation, whereas management of patients with systemic PHA type 1 proves more difficult as they are likely to get frequent episodes of electrolyte imbalance requiring urgent correction.

Learning points

  • Patients with type 1 PHA are likely to present in the neonatal period with hyponatraemia, hyperkalaemia and metabolic acidosis and can be diagnosed by the significantly elevated plasma renin activity and aldosterone levels.

  • The differential diagnosis of type 1 PHA includes adrenal disorders such as adrenal hypoplasia and congenital adrenal hyperplasia; thus, adrenal function including cortisol levels, 17-hydroxyprogesterone and a urinary steroid profile are required. Secondary (transient) causes of PHA may be due to urinary tract infections or renal anomalies; thus, urine culture and renal ultrasound scan are required respectively.

  • A differentiation between renal and systemic PHA type 1 may be made based on sodium requirements, ease of management of electrolyte imbalance, sweat test results and genetic testing.

  • Management of renal PHA type 1 is with sodium supplementation, and requirements often decrease with age.

  • Systemic PHA type 1 requires aggressive and intensive fluid and electrolyte management. Securing an enteral feeding route and i.v. access are essential to facilitate ongoing therapy.

  • In this area of the UK, the incidence of AD PHA and AR PHA was calculated to be 1:66 000 and 1:166 000 respectively.