Reply to “more on non-alcohol/non-metabolic dysfunction-associated steatohepatitis”
Authors: Kymberly D. Watt, Mohammad Qasim Khan
Journal: Hepatology (2023)

We appreciate the letter from Drs Vajro and Mandato, highlighting the complexities of this classification of steatohepatitis disorders. They bring up an important concept relating to genetic diseases and consanguinity that may vary globally. We did not address this issue and bringing attention to this for a global audience is helpful. They correctly highlight additional specific rare diagnoses within the genetic and metabolic category that can be associated with steatohepatitis presentations. Enveloped into metabolic and genetic causes including mitochondrial hepatopathy, we did not specifically highlight muscular dystrophies as the associated steatosis is most likely related to the metabolic derangements including insulin resistance, hypertriglyceridemia, and hormonal imbalances that result in the steatosis and less likely the direct effect of muscular dystrophy. Given the pituitary and adrenal hormonal imbalances, these patients do present with more advanced fibrosis, which should have been acknowledged in the article. Most of these patients would already have a diagnosis of muscular dystrophy making a creatinine kinase level unlikely helpful. Importantly though, they remind us that the included diseases within genetic fatty acid and lipid storage diseases were not exhaustive. We are grateful for the attention to the example of the neutral lipid storage disease, a rare (<100 reported cases) disease associated with hepatic steatosis and lipid droplets in white blood cells, skin, and muscles among other organs. This entity would be diagnosed by clinical presentation (skin changes, muscular weakness, etc) combined with the identification of lipids in tissues, and certainly, adding a creatinine kinase level to blood testing if this was a clinical consideration would be appropriate in both age groups. It is challenging to include all possible genetic disorders linked with steatosis and we are grateful to have this chance to remind readers to look more deeply into rare genetic causes when atypical presentations arise. Lean metabolic associated steatotic liver disease is a vexing issue that has more questions than answers and was not addressed directly in the review. While the new definitions of metabolic associated steatotic liver disease do not overtly subdivide patients based on differing cardiometabolic criteria (eg, BMI ≥25 kg/m2 or BMI <25 kg/m2), previous literature has identified lean individuals with metabolic associated steatotic liver disease as having different rates of disease progression, associated conditions, and cardiometabolic risk. There remain areas of unmet need in this population that require further, ongoing study and investigation. In the case of lean celiac disease, the referenced study also hypothesized similar relationships between the intestinal microbiome and nutrient imbalances to their finding of increased steatosis in treated celiac disease (both lean and obese). Readers are directed to the additional reference for this interesting topic. Lastly, we welcome the reminder that our discussion of toxins associated with steatosis was also not exhaustive and missed the inclusion of bisphenol A and phthalates (and undoubtedly more to surface), allowing us another opportunity to direct the reader to look for these (and other) important potential contributors to steatosis. We are happy to have this review stimulate such thoughtful and helpful insights by the Hepatology readership.