Mitochondrial trifunctional protein deficiency due to HADHB gene mutation in a Chinese family

Area of Science:

• Biochemistry
• Genetics
• Neurology

Background:

• Mitochondrial trifunctional protein (MTP) deficiency is a rare autosomal recessive disorder of fatty acid oxidation.
• It results from mutations in HADHA or HADHB genes, affecting energy metabolism.
• Diagnosis can be challenging due to varied clinical presentations.

Purpose of the Study:

• To report a case of MTP deficiency in an 8-year-old girl with congenital lower limb weakness.
• To characterize the genetic mutation and clinical phenotype.
• To highlight the neuromyopathic presentation and its potential for neonatal onset.

Main Methods:

• Clinical evaluation including electromyography (EMG) and muscle biopsy.
• Biochemical analysis of blood acylcarnitine levels.
• Genetic analysis of the HADHB gene.

Main Results:

• The patient presented with progressive lower limb weakness since birth.
• EMG and muscle biopsy indicated peripheral nerve injury and a neurogenic lesion.
• Analysis revealed a homozygous missense mutation c.739C>T (p.R247C) in the HADHB gene.
• Slightly increased long-chain 3-OH-acylcarnitine levels were observed.

Conclusions:

• This case represents the first report of MTP deficiency in the Chinese population.
• The identified HADHB mutation expands the known genetic causes of MTP deficiency.
• The neuromyopathic phenotype with likely neonatal onset is a rare presentation of MTP deficiency.