Propionic acidemia and methylmalonic aciduria: A portrait of the first 3 years-Admissions and complications

Propionic acidemia (PA) and methylmalonic acidemia (MMA) are organic acidurias that can present with metabolic acidosis and hyperammonemia, often leading to frequent hospital admission. While recent studies have provided guidelines for management and diagnosis of these conditions, there is a lack of research detailing the frequency and reasons for hospital admission in the first three years of life.

As part of a quality improvement project, data were extracted from medical records of all patients with PA and MMA (born between 2000 and 2024) who were seen at Children's National Hospital (CNH) during their first three years of life, time of data pull, or up to point of liver transplant. We collected data on the number of individuals with PA or MMA in our patient population, the age at which they first presented, and the reason for their hospital admission.

Our cohort included 11 individuals with MMA, all of whom had MMUT mutations, representing a total of 12 different variants. Additionally, 15 individuals with PA were reported. Of these, 2 individuals with PA did not undergo genetic testing, 5 had 7 separate variants in PCCA gene, and 8 had 10 different variants in PCCB gene. The mean number of hospitalizations for metabolic decompensation was 4.45 ± 6.6 for the MMA cohort and 8.7 ± 6.7 for the PA cohort, with no statistically significant difference between the groups. The MMA cohort experienced a total of 49 admissions, 16 (33 %) of which occurred in the first year of life. In the PA cohort, there were 130 total admissions, with 56 (43 %) occurring in the first year. The most frequent reason for admission in both groups was vomiting.

Individuals with PA and MMA are frequently hospitalized (accounting for 5-6 % of their first three years of life) which likely impacts development and overall health. Data such as those presented in this study are crucial for improving our understanding of disease progression in these rare conditions. This information can help guide future research, support the development of the clinical guidelines, and provide healthcare providers with valuable insights to better educate families on risks and expectations. Using these data, we have altered our counseling at the time of diagnosis to better prepare families for their child's course.