What Is 3-Methylglutaconic aciduria type V

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Last updated: April 15, 2026

Quick Answer: 3-Methylglutaconic aciduria type V is a rare genetic disorder caused by mutations in the DNAJC19 gene, first identified in 2006, leading to impaired mitochondrial function and characterized by 3-methylglutaconic acid buildup in urine.

Key Facts

3-Methylglutaconic aciduria type V was first described in 2006 by researchers studying patients with dilated cardiomyopathy and 3-methylglutaconic aciduria.
It is caused by mutations in the DNAJC19 gene located on chromosome 2q11.2.
The disorder follows an autosomal recessive inheritance pattern.
Over 50 cases have been reported worldwide, primarily in individuals of Middle Eastern or Mennonite descent.
Clinical features include cardiomyopathy, developmental delay, microcephaly, and growth retardation.

Overview

3-Methylglutaconic aciduria type V is a rare autosomal recessive metabolic disorder affecting mitochondrial function. It is one of several subtypes of 3-methylglutaconic aciduria, distinguished by specific genetic and clinical features.

The condition results in the accumulation of 3-methylglutaconic acid and 3-methylglutaric acid in urine, a hallmark used in diagnosis. Symptoms typically appear in infancy and progress rapidly without intervention.

DNAJC19 gene mutations cause the disorder, disrupting mitochondrial protein import and leading to energy production deficits in cells.
The condition was first linked to chromosome 2q11.2 in 2006 through genetic analysis of affected patients from consanguineous families.
It is most prevalent among Mennonite and Middle Eastern populations, where founder mutations increase carrier frequency.
Diagnosis involves urine organic acid analysis, which shows elevated 3-methylglutaconic and 3-methylglutaric acids, confirmed by genetic testing.
Unlike other types, type V is strongly associated with dilated cardiomyopathy, often leading to heart failure in early childhood.

How It Works

The disorder disrupts mitochondrial dynamics due to defective protein chaperone function, primarily affecting high-energy tissues like the heart and brain.

DNAJC19 protein: This mitochondrial chaperone helps regulate protein import across the inner mitochondrial membrane; mutations impair this process, causing metabolic stress.
Mitochondrial dysfunction: Impaired protein folding leads to reduced ATP production and increased oxidative stress, damaging cardiac and neural tissues.
Organic acid accumulation: Due to disrupted leucine metabolism, 3-methylglutaconic acid builds up, serving as a diagnostic biomarker detectable in urine.
Autosomal recessive inheritance: Both parents must be carriers; each child has a 25% chance of inheriting two mutated copies and developing the disease.
Onset in infancy: Symptoms typically appear before age 1, including poor feeding, developmental delay, and progressive cardiac enlargement.
Microcephaly and growth failure: Neurological impairment manifests as reduced head growth and failure to thrive, evident within the first year of life.

Comparison at a Glance

Below is a comparison of 3-methylglutaconic aciduria types I–V to highlight distinguishing features:

Type	Gene	Inheritance	Key Clinical Features	Prevalence
Type I	AUH	Autosomal recessive	Mild neurological symptoms, speech delay	Rare
Type II	TAZ (G4.5)	X-linked	Barth syndrome: cardiomyopathy, neutropenia	~1 in 200,000 males
Type III	OPA3	Autosomal recessive	Optic atrophy, movement disorders	Very rare
Type IV	Unknown	Autosomal recessive	Severe encephalopathy, early death	Extremely rare
Type V	DNAJC19	Autosomal recessive	Dilated cardiomyopathy, microcephaly, growth failure	~50 reported cases

Type V is clinically distinct due to its strong association with early-onset cardiomyopathy and specific genetic cause. While other types may present with neurological or metabolic symptoms, type V’s cardiac involvement is a primary diagnostic clue. Genetic screening for DNAJC19 mutations is recommended in infants with unexplained heart failure and elevated urinary organic acids.

Why It Matters

Understanding 3-Methylglutaconic aciduria type V is crucial for early diagnosis and management of affected infants, particularly in high-risk populations.

Early genetic testing can confirm diagnosis before severe cardiac damage occurs, enabling timely intervention.
Carrier screening in Mennonite and Middle Eastern communities helps reduce incidence through informed family planning.
Heart failure management with medications like beta-blockers and ACE inhibitors improves survival and quality of life.
Metabolic monitoring allows for dietary adjustments and avoidance of catabolic stress that worsens symptoms.
Research into chaperone therapies may one day correct mitochondrial protein import defects at the molecular level.
Improved newborn screening protocols could include DNAJC19 testing in regions with high carrier rates.

Despite its rarity, type V underscores the importance of integrating genetics, metabolism, and cardiology in pediatric medicine. As genomic medicine advances, early detection and targeted therapies offer hope for better outcomes.