# The Ketogenic Diet in the Neonatal Intensive Care Setting: The Case of a Preterm Newborn With Mitochondrial DNA Depletion Syndrome Type 13 (MTDPS13)

## TL;DR

A preterm baby with a rare mitochondrial disorder was treated with a ketogenic diet early in life, showing improved clinical and biochemical outcomes.

## Contribution

First documented use of a ketogenic diet in a preterm neonate with MTDPS13 during early life.

## Key findings

- Early initiation of a ketogenic diet led to reduced lactate levels and improved acid-base balance.
- The infant showed clinical and cardiovascular improvements during treatment.
- Stability in clinical and biochemical markers was maintained after discharge and during follow-up.

## Abstract

Mitochondrial DNA depletion syndrome 13 (MTDPS13) is an autosomal recessive disorder presenting in early infancy with encephalopathy, hypotonia, lactic acidosis, and severe global developmental delay. Patient‐derived cells typically exhibit impaired mitochondrial oxidative phosphorylation and a marked reduction in mitochondrial DNA (mtDNA) copy number.

We report the case of a male preterm neonate born at 31 + 3 weeks of gestation following a pregnancy marked by severe polyhydramnios. At birth, his weight was 1400 g. Physical examination revealed dysmorphic features, redundant and lax skin, and generalized muscular hypotonia. Laboratory investigations showed marked lactic acidosis associated with lactic aciduria, ketonuria, and urinary biomarkers indicating activation of preoxidative phosphorylation biochemical pathways to sustain ATP production. Echocardiography demonstrated mild, early‐onset hypertrophic cardiomyopathy.

The Exome Analysis Clinical and Biochemical Markers: The exome analysis, performed within the first week of life, highlighted a pathogenic variant in homozygous state of FBXL4 gene (c.1648_1649delGA), which led to the diagnosis of MTDPS13. In this clinical contest, a ketogenic diet (KD) was started with a daily caloric intake of 120 kcal/kg and an initial ketogenic ratio of 1:1. These intakes were administered both with a parenteral nutrition and continuous nasogastric tube feeding and were gradually increased and adapted on a day‐by‐day basis according to lactic acidosis, growth increase, and common metabolic parameters such as glucose, electrolytes, creatinine, and blood urea nitrogen. After 3 days of this treatment approach, a significant reduction in lactate levels and improvement in acid–base balance and growth trend were observed along with clinical and cardiovascular parameters. At discharge from neonatal intensive care unit, the KD was continued at home and during follow‐up. The infant showed stability in the clinical and biochemical markers.

This is the first documented report of the use of a KD in a preterm neonate with this mitochondrial disorder during the early days of life. Prompt genetic confirmation and early initiation of KD may enable a more targeted and effective management of MTDPS within the neonatal intensive care setting.