Table 1.
Characteristics of Patients with HNF1A Variants During Pregnancy and Their Infants
| Case | 1 | 2 | 3 |
|---|---|---|---|
| Maternal diabetes diagnoses (age at diagnosis) | T1D (8), T2D (9), HNF1A MODY (15) |
T1D (22), HNF1A MODY (33) |
GDM (22), T2D (23), possible HNF1A MODY (26) |
| Maternal BMI (kg/m2), outside of pregnancy | 28.8-29.6 | 22.8-24.0 | 30.4 (prior to pregnancy), 38.5-40.5 (postpartum) |
| Maternal glycemic control during pregnancy (HbA1C [mmol/mol, %] and either SMBG or CGM ranges [mg/dL]) | HbA1C, 27-33 mmol/mol; 4.6%-5.2% Fasting: 60-110 mg/dL Postprandial: 100-184 mg/dL |
HbA1C, 33 mmol/mol; 5.2% CGM mean ± SD glucose: 87-102 ± 22-29 mg/dL |
HbA1C, 43-46 mmol/mol; 6.1%-6.4% Fasting: 90-125 mg/dL Postprandial: 85-200 mg/dL |
| Infant birth weight (percentile) | 4.38 kg (>99th) | 3.90 kg (>99th) | 5.81 kg (>99th) |
| Infant glycemic phenotype (duration of hypoglycemic events) | Presumed congenital hyperinsulinism (hypoglycemia >1 y) | Neonatal hypoglycemia (<1 mo) | Presumed congenital hyperinsulinism (hypoglycemia >1 y) |
| Infant genetic testing result | HNF1A c.811C>T, p.Arg271Trp | HNF1A c.326+1G>T; splice donor | HNF1A c.794A>G, p.Tyr265Cys |
| HNF1A variant classification | Pathogenic | Pathogenic | VUS |
| Additional genetic variants found | None known | Mother only: VUS in SLC2A2 (c.1068+5G>A) | None known |
| Additional infant phenotype | Feeding difficulty | Feeding difficulty | Feeding difficulty, hypotonia |
| Other potential etiologies of neonatal hypoglycemia or CHI | None found, although maternal diabetes control was slightly above goal | Maternal history of chorioamnionitis | None found, although maternal diabetes control was moderately above goal |
Abbreviations: BMI = body mass index; CGM = continuous glucose monitoring; CHI = congenital hyperinsulinism; GDM = gestational diabetes; HbA1C = hemoglobin A1C; HNF1A = hepatocyte nuclear factor 1α; MODY = maturity-onset diabetes of the young; SMBG = self-monitoring of blood glucose; T1D = type 1 diabetes; T2D = type 2 diabetes; VUS = variant of uncertain significance.