HSD3B7 and hyperinsulinemic hypoglycemia, familial, 4: In the largest study of patients with HSD3B7 deficiency, capital Zhao et al[22] categorized the gene variants into 2 classes: null variants (including frameshift, nonsense, classical splicing variants and large fragment deletions) and non-null variants (including missense, non-classical splicing and non-frameshift small indel types, no significant differences were observed in terms of clinical outcome among the patients with different genotypes.