SUN-556 - A Curious Case of A 38-Year-Old Gentleman with Atypical Presentation of HNF1B Associated Maturity Onset Diabetes of the Young

Background:
Maturity Onset Diabetes of the Young (MODY) can be confused with Type 1 or Type 2 Diabetes Mellitus (DM) in clinical practice given syndromic overlap leading to delays in guideline therapy. Lack of general awareness in the medical care provider community compounded with restrictive costs of genomic testing has led to an underappreciation of the prevalence of MODY, which in turn prevents adequate patient care. High clinical suspicion is often required along with close follow-up to make the diagnosis. Here we describe a case of newly diagnosed MODY5 with confirmatory HNF1B gene testing in which there was development of chronic kidney disease without evidence of autoimmune-associated decline in endogenous insulin production.

Case:
A 38-year-old male patient with past medical history including seasonal allergies not on any prescription medications, over the counter medications, vitamins or herbal supplements who presented to his primary care physician for routine annual follow up where he was noted to have elevated creatinine (Cr) level of 1.3 mg/dL with an estimated glomerular filtration rate (eGFR) of 68 mL/min/1.73 m² on routine testing coupled with fasting glucose of 106mg/dL. These findings prompted outpatient nephrology referral and subsequent testing three months later demonstrated biochemically similar values for Cr and eGFR prompting renal sonography which revealed increased bilateral renal cortical echogenicity with findings of one solitary right superior pole cyst measuring 1.3 x 1.0 x 0.9cm. Subsequent gene testing revealed an autosomal dominant likely pathologic HNF1B (variant c.356G>A (p.Trp119*)). Pt followed up with outpatient endocrinology for further recommendations regarding management of MODY5. Subsequent positive c-peptide level suggested biochemical endogenous insulin production along with negative glutamic acid decarboxylase, islet cell antibody, insulin level and insulin autoantibody.

Conclusion:
This case highlights a variation in our clinical considerations for the target patient population of MODY5 given that our patient had begun to demonstrate biochemical and sonographic changes at the age of 38 where most documented cases of MODY5 occur in North America before age 25. This subclassification of MODY responds to insulin therapy as opposed to oral agents but at this time our patient has not demonstrated overt pathologic levels of hyperglycemia or glycemic-related cardiovascular-metabolic decline. He is at risk for future development of these complications and so we continue to routinely follow. Consideration was given to the usage of a continuous glucose monitor system to better understand this patient’s personal glycemic reaction to his regular daily dietary intake.

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