A Complicated Pregnancy in an Adult with HNF4A p.R63W-Associated Fanconi Syndrome

Abstract

Renal Fanconi syndrome (RFS) is characterised by generalised dysfunction of the proximal renal tubules, resulting in excessive urinary loss of solutes, most notably bicarbonate, and type II (proximal) renal tubular acidosis. It is a rare condition, and literature around its management through pregnancy is limited. We present the management of a 37-year-old woman with RFS secondary to the HNF4A p.R63W mutation, through her third pregnancy. She presented at 28 + 5 weeks with dehydration, low serum bicarbonate, and profound metabolic acidosis. Daily infusions of sodium bicarbonate were necessary, and the requirements increased throughout the pregnancy. She also demonstrated both fasting hypoglycaemia and episodes of postprandial hyperglycaemia which required complex management. Due to concerns around fetal health, an elective caesarean section was performed at 34 weeks, delivering a healthy baby girl. This case highlights the potential complexity of pregnancy in patients with RFS and the need for a multidisciplinary approach to its management.

Expanding the p.(Arg85Trp) Variant-Specific Phenotype of HNF4A: Features of Glycogen Storage Disease, Liver Cirrhosis, Impaired Mitochondrial Function, and Glomerular Changes

“…Thus, a common loss-of-function effect appears, not to explain the specific impact on the proximal tubular function sufficiently; instead, we hypothesize that the above-described gain-of-function concept could be applicable to this issue. In contrast to the proximal tubulopathy observed in most patients, CKD is only described in one other patient [ Anyiam et al, 2019 ]. Our patient's histology also exhibited segmental glomerular changes, suggestive of a glomerular component impacting her kidney.…”

Corticosteroid-induced bradycardia in multiple sclerosis and maturity-onset diabetes of the young due to hepatocyte nuclear factor 4-alpha mutation: A case report

“…Flattening and inversion of T-waves have been known to be associated with hypokalemia. Patients with HNF4A mutations have defective proximal tubule function[ 20 , 21 ] and are prone to urinary loss of serum potassium[ 21 ]. Moreover, despite methylprednisolone generally having a minimal mineralocorticoid effect[ 22 ], serum potassium may decrease in response to a pulsed dose of methylprednisolone[ 23 ].…”