Diabetes and CFAP126 gene mutation; are they really linked together?

OBJECTIVES: We are reporting a rare case series of 2 siblings and their mother with diabetes having a CFAP126 gene mutation. CASE PRESENTATION: Two female siblings, presented with incidental hyperglycemia at the ages of 16 and 13. They had a strong family history of diabetes on the maternal side. The systemic examination was unremarkable. Sibling 1 had HbA1C of 12.3 % with insulin and C-peptide levels of 6.6 IU/L and 1.8 ng/mL, respectively. Sibling 2 had an HbA1C of 12.6 %, an insulin level of 7.3 IU/L, and a C-peptide level of 2.02 ng/mL. Anti-GAD-65 and IA2 antibodies were negative. Mother also shared similar clinical processes and exhibited comparable biochemical changes related to glucose metabolism with elevated HbA1C levels and negative autoimmune markers (anti-GAD65 and IA2 antibodies). Whole exome sequencing (WES) turned out to be negative for MODY variants but revealed a rare heterozygous mutation in the CFAP126 gene (c.310A>T p. (Lys104*) in this family including both siblings and mother. The pathogenicity prediction tool MutationTaster® classified the mutation as disease causing. Oral glibenclamide remarkably reduced insulin requirements and improved HbA1C levels. CONCLUSIONS: This rare genetic mutation is likely associated with diabetes and possibly a novel marker for a yet to be identified type of diabetes, that is responsive to oral sulfonylureas. The influence of this gene on insulin secretion needs to be confirmed through future research.