Macrosomia and hyperinsulinaemic hypoglycaemia in patients with heterozygous mutations in the HNF4A gene

Abstract

Background: Macrosomia is associated with considerable neonatal and maternal morbidity. Factors that predict macrosomia are poorly understood. The increased rate of macrosomia in the offspring of pregnant women with diabetes and in congenital hyperinsulinaemia is mediated by increased foetal insulin secretion. We assessed the in utero and neonatal role of two key regulators of pancreatic insulin secretion by studying birthweight and the incidence of neonatal hypoglycaemia in patients with heterozygous mutations in the maturity-onset diabetes of the young (MODY) genes HNF4A (encoding HNF-4alpha) and HNF1A/TCF1 (encoding HNF-1alpha), and the effect of pancreatic deletion of Hnf4a on foetal and neonatal insulin secretion in mice.

Methods and findings: We examined birthweight and hypoglycaemia in 108 patients from families with diabetes due to HNF4A mutations, and 134 patients from families with HNF1A mutations. Birthweight was increased by a median of 790 g in HNF4A-mutation carriers compared to non-mutation family members (p < 0.001); 56% (30/54) of HNF4A-mutation carriers were macrosomic compared with 13% (7/54) of non-mutation family members (p < 0.001). Transient hypoglycaemia was reported in 8/54 infants with heterozygous HNF4A mutations, but was reported in none of 54 non-mutation carriers (p = 0.003). There was documented hyperinsulinaemia in three cases. Birthweight and prevalence of neonatal hypoglycaemia were not increased in HNF1A-mutation carriers. Mice with pancreatic beta-cell deletion of Hnf4a had hyperinsulinaemia in utero and hyperinsulinaemic hypoglycaemia at birth.

Conclusions: HNF4A mutations are associated with a considerable increase in birthweight and macrosomia, and are a novel cause of neonatal hypoglycaemia. This study establishes a key role for HNF4A in determining foetal birthweight, and uncovers an unanticipated feature of the natural history of HNF4A-deficient diabetes, with hyperinsulinaemia at birth evolving to decreased insulin secretion and diabetes later in life.

Figure 1. Birthweight (Adjusted for Sex and Gestational Age) according to Foetal Genotype

(A) All offspring; (B) HNF4A mutation inherited from the father; (C) HNF4A mutation inherited from the mother, and (D) siblings discordant for HNF4A genotype. Foetal genotype: NM, heterozygous HNF4A mutation; NN, normal HNF4A. For (A) to (C), bars represent median, the box represents interquartile range, and the whiskers represent the range, with outliers shown as circles. Comparing NM birthweight with NN birthweight by Mann-Whitney U-test: p < 0.001 for (A) all offspring; p = 0.001 for (B) father affected and for (C) mother affected. In (D), those pairs where the father has the mutation are shown as filled circles; those pairs where the mother has the mutation are shown as filled triangles. The red bars represent median birthweight.

Figure 2. Pedigrees of Families with Hypoglycaemia

Patients with hypoglycaemia are shaded with bold diagonal stripes; patients who had hypoglycaemia but have progressed onto diabetes are shaded with half black/half diagonal stripes; and patients with diabetes are coloured black. Probands are indicated with an arrow. Where available, below each symbol is recorded genotype (NM, HNF4A-mutation carrier; NN, unaffected), birth centile adjusted for sex and gestation, age at which diabetes developed, and the patient's treatment.

Figure 3. Deletion of Hnf4a in β-Cells Results in Hyperinsulinaemia and Hypoglycaemia in Mice

(A) Blood glucose, plasma insulin, and insulin/glucose ratio of E18.5–E20 embryos. (B) Blood glucose levels, plasma insulin levels, and insulin/glucose ratio of newborn mice. Data from β-Hnf4a-KO and controls is shown in white and black bars, respectively. Values are mean ± standard error of the mean.

Figure 4. Birthweight in HNF1A-Mutation Carriers

(A) Median centile (adjusted for sex and gestation) in mutation carriers (NM) and non-mutation carriers (NN) (p = 0.86). Error bars show interquartile range. (B) Discordant sib-pair analysis. Those pairs where the father has the mutation are shown as filled circles; those pairs where the mother has the mutation are shown as filled triangles. Median birthweight: NM 3,490 g; NN 3460 g (p = 0.91).