Pseudohypodosteronism type 1 (PHA-1) is an inherited disease caused by the resistance of peripheral tissues to aldosterone, leading to severe salt loss in infants. This rare disease is caused by mutations in the amiloride-sensitive epithelial sodium channel subunits (ENaCs). Loss-of-function mutations in ENaCs lead to PHA-1, which is associated with neonatal salt wasting. PHA1 can be transmitted as autosomal dominant and recessive forms. Patients with the autosomal dominant form of PHA1 have milder symptoms and more renal involvement. The autosomal recessive form of PHA1 is more severe and resistant to mineralocorticoids is seen in several organs such as the kidney and colon, sweat and salivary glands.
Case report: Here we report a severe form of the disease that resulted in the death of several children in the family. Our patient was the seventh child in the family and the result of a first degree cousin marriage. The first, third, fourth children of the family, who were boys, and the sixth child of the family, who was a girl, died shortly after birth from PHA1, respectively. These children were hospitalized in another city. The second child of the family is a girl and the fifth child of the family, who is a boy, is healthy and alive. Our patient weighed 3,500 grams at birth and had a height and head circumference 51 and 35.5 cm, respectively. The patient had severe vomiting and poor feeding from the second day of birth and transferred to the NICU. Due to the death of previous children and the history of PHA1 in his family, the necessary studies were performed. ACTH and other sex steroids were in the normal range. Renin and aldosterone levels were very high. Serum potassium was 9 meq / l and sodium was 110 meq / l. His skin was not hyperpigmented and he had a normal external genitals. At the age of 5, he is 109 cm tall and weighs 18 kg and his growth and development is normal.
Genetic study: In this patient, a novel homozygous missense mutation (c.1497G>C) in exon 10 of SCNN1A gene was identified, changing Glutamine 499 to Histidine (P. Gln499His). Sanger sequencing was used to validate the detected variant. Segregation analysis using Sanger sequencing revealed that both parents showed heterozygosity at the mutation position.
Conclusion: Identifying this mutation can help diagnose new patients with Pseudohypoaldosteronism Type 1.
15 Sep 2022 - 17 Sep 2022