EPHX1 mutations cause a lipoatrophic diabetes syndrome due to impaired epoxide hydrolysis and increased cellular senescence

Epoxide hydrolases (EHs) regulate cellular homeostasis through hydrolysis of epoxides to less-reactive diols. The first discovered EH was EPHX1, also known as mEH. EH functions remain partly unknown, and no pathogenic variants have been reported in humans. We identified two de novo variants located in EPHX1 catalytic site in patients with a lipoatrophic diabetes characterized by loss of adipose tissue, insulin resistance, and multiple organ dysfunction. Functional analyses revealed that these variants led to the protein aggregation within the endoplasmic reticulum and to a loss of its hydrolysis activity. CRISPR-Cas9-mediated EPHX1 knockout (KO) abolished adipocyte differentiation and decreased insulin response. This KO also promoted oxidative stress and cellular senescence, an observation confirmed in patient-derived fibroblasts. Metreleptin therapy had a beneficial effect in one patient. This translational study highlights the importance of epoxide regulation for adipocyte function and provides new insights into the physiological roles of EHs in humans.

EPHX1 mutations cause a lipoatrophic diabetes syndrome due to impaired epoxide hydrolysis and increased cellular senescence

Epoxide hydrolases (EHs) regulate cellular homeostasis through hydrolysis of epoxides to less reactive diols. The first discovered EH was EPHX1, also known as mEH. EH functions remains partly unknown and no pathogenic variants have been reported in humans. We identified two de novo variants located in EPHX1 catalytic site in patients with a lipoatrophic diabetes characterized by loss of adipose tissue, insulin resistance, and multiple organ dysfunction. Functional analyses revealed that these variants led to the protein aggregation within the endoplasmic reticulum and to a loss of its hydrolysis activity. CRISPR-Cas9-mediated Ephx1 knockout (KO) abolished adipocyte differentiation and decreased insulin response. This KO also promoted oxidative stress and cellular senescence, an observation confirmed in patient-derived fibroblasts. A major beneficial effect of metreleptin therapy was observed. This translational study highlights the importance of epoxide regulation for adipocyte function, and provides new insights into the physiological roles of EHs in humans.

Combination of lipoatrophic diabetes mellitus with systemic scleroderma and phenylketonuria

We present the first report of a rare form of lipoatrophic diabetes mellitus in a child with partial autoimmune lipodystrophy combined with systemic scleroderma and phenylketonuria. We describe the features of clinical manifestations, diagnosis, and therapy. To exclude the monogenic form of lipodystrophy, we performed a molecular genetic analysis of genes ZMPSTE24, LMNA, BSCL2, PLIN1, PTRF, LMNB2, POLD1, AKT2, CIDEC, PIK3CA, PPARG, PSMB8, CAV1, PPP1R3A, and AGPAT2 that are responsible for the development of lipodystrophy and insulin resistance. No mutations were found. The presence of systemic scleroderma of autoimmune genesis enabled the diagnosis of autoimmune lipodystrophy. Treatment of insulin-resistant diabetes mellitus in lipodystrophy is a challenge: biguanide therapy is dangerous due to impairment of liver functions, and insulin therapy is not effective enough; administration of high doses is required. The presence of phenylketonuria further complicates compliance with the dietary regimen. The combination of three rare diseases ― lipoatrophic diabetes, phenylketonuria, and systemic scleroderma ― in one patient has not been found in the available literature.

CLINICAL CASE OF LAWRENCE LIPOATROPHIC DIABETES

This article describes a clinical case of Lawrence lipoatrophic diabetes patient who was born in 1963. The differential diagnosis with gipermuskulin lipodystrophy. Diagnostic criteria of Lawrence lipoatrophic diabetes were shown. They are specific patient’s appearance big changes in carbohydrate and lipid metabolism. The dynamics of the patient’s status on the background of symptomatic therapy was evaluated.