Inborn errors of metabolism and pregnancy.

As the diagnosis and treatment of patients with inborn errors of metabolism has improved dramatically over the years, more people with these conditions are surviving into child-bearing years. Given the changes in metabolism throughout pregnancy, this time presents a unique challenge in their care. Overall metabolic shifts in pregnancy go from anabolism to catabolism driven by endocrinologic changes, along with changes in rates of gluconeogenesis, glucose consumption, amino acid transport, protein consumption, and lipid breakdown, result in a complicated metabolic picture. Additionally, maternal inborn errors of metabolism can affect a fetus, as in phenylketonuria, and fetal inborn errors of metabolism can affect the mother, as in certain fatty acid oxidation disorders. Data on these conditions is often very limited. A summary of the current literature, risks associated with pregnancy in inborn errors of metabolism, and suggestions for management of these conditions will be presented.

Acute myeloid leukemia and dilated cardiomyopathy in a pediatric patient with D-2-hydroxyglutaric aciduria type I.

D-2-hydroxyglutaric aciduria (D-2-HGA) is a rare neurometabolic disease with two main subtypes, caused by either inactivating variants in D2HGDH (type I) or germline gain of function variants in IDH2 (type II), that result in accumulation of the same toxic metabolite, D-2-hydroxyglutarate. The main clinical features of both are neurologic, including developmental delay, hypotonia, and seizures. Dilated cardiomyopathy is a unique feature thus far only reported in type II. As somatic variants in IDH2 are frequently identified in several different types of cancer, including acute myeloid leukemia (AML), a link between cancer and this metabolic disease has been proposed; however, there is no reported cancer in patients with either type of D-2-HGA. Murine models have demonstrated how D-2-hydroxyglutarate alters metabolism and epigenetics, a potential mechanism by which this metabolite may cause cancer and cardiomyopathy. Here, we report the first case of both AML and dilated cardiomyopathy in a pediatric patient with D-2-HGA type I, who was treated with an anthracycline-free regimen. This report may expand the clinical spectrum of this rare metabolic disease and provide insight on long-term surveillance and care. However, this case is complicated by the presence of a complex chromosomal rearrangement resulting in a 25.5 Mb duplication of 1q41 and a 2.38 Mb deletion of 2q37.3. Thus, the direct causal relationship between D-2-HGA and leukemogenesis or cardiomyopathy warrants further scrutiny.