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  • Test code: 06206
  • Turnaround time:
    10–21 calendar days (14 days on average)
  • Preferred specimen:
    3mL whole blood in a purple-top tube
  • Alternate specimens:
    DNA or saliva/assisted saliva
  • Sample requirements
  • Request a sample kit
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Invitae 3-Methylglutaconic Aciduria Panel

Test description

The Invitae 3-Methylglutaconic Aciduria Panel analyzes 8 genes that are associated with elevations 3-methylglutaconic acid on urine organic acid analysis. Genetic testing of these genes may confirm a diagnosis and help guide treatment and management decisions. Identification of disease-causing variants can also provide accurate risk assessment and carrier status for at -risk relatives.

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Primary panel (8 genes)

AUH CLPB CPS1 DNAJC19 OPA3 SERAC1 TAZ TMEM70

Alternative tests to consider

For a broader analysis of the genetics of organic acidemia:

GeneDisorder
AUH 3-methylglutaconyl-CoA hydratase deficiency
CLPB 3-methylglutaconic aciduria with cataracts, neurologic involvement and neutropenia (MEGCANN)
CPS1 carbamoyl phosphate synthetase 1 deficiency
DNAJC19 dilated cardiomyopathy with ataxia (DCMA) syndrome
OPA3 Costeff syndrome
SERAC1 Megdel syndrome
TAZ Barth syndrome
TMEM70 mitochondrial complex 5 deficiency

Elevated 3-methylglutaconic acid may be detected on urine organic acid analysis due to multiple inherited disorders. Primary 3-methylglutaconic aciduria is due to 3-methylglutaconyl-CoA hydratase deficiency. Patients with this disorder can present in childhood or later in life. Features have included intellectual disability, seizures, hepatopathy, encephalopathy, dysarthria, ataxia, athetoid movement disorder, and progressive leukoencephalopathy, but findings are variable from patient to patient.

Secondary 3-methylglutaconic aciduria is caused by a heterogenous group of disorders that can affect phospholipid remodeling, are associated with the mitochondrial membrane, or remain unknown. Patients with Barth syndrome have cardiomyopathy, neutropenia, skeletal muscle weakness, growth retardation, and intellectual disability. Presentation and severity are variable. In addition to 3-methylglutaconic aciduria, patients with MEGDEL syndrome (also known as MEGDHEL) have deafness, hepatic involvement, encephalopathy, and Leigh syndrome. Hepatic involvement can range anywhere from neonatal hypoglycemia to fulminant liver failure. Regression, dystonia, spasticity, and seizures often present by 2 years of age. Costeff syndrome patients have infantile onset bilateral optic atrophy. Other features include spasticity, extrapyramidal signs, ataxia, dysarthria, and cognitive deficits. DCMA syndrome is characterized by early onset dilated cardiomyopathy and ataxia in addition to 3-methylglutaconic aciduria. Patients with a TMEM70 defect have a variable phenotype which may include, hypertrophic cardiomyopathy, myopathy, dysmorphism, cataracts, psychomotor retardation, lactic acidosis and hyperammonemia. Roughly half of the patients survive past the first week of life. CLPB deficiency (also known as MEGCANN deficiency) ranges from a severe disorder to mild with most patients having a severe neonatal onset. Features include neutropenia accompanied by neurological abnormalities such as hyperekplexia, tonal abnormalities, dysphagia, respiratory insufficiency, microcephaly and seizures. The degree of neutropenia and extent of neurological abnormalities depend on the severity of the disorder. Patients with CPS1 deficiency, a proximal urea cycle disorder, have recently been shown to have 3-methylglutaconic aciduria. CPS1 patients have a severe clinical course often includes hyperammonemic encephalopathy with symptoms such as lethargy, poor feeding, vomiting, and seizures that can lead to coma and death if untreated.

Primary and secondary 3-methylglutaconic aciduria that causes persistent elevations of 3-methylglutaconic acid is very rare. Due to the rarity of this condition, the percent of 3-methylglutaconic aciduria attributed to pathogenic variants in genes on this panel is currently unknown.

Most genetic causes of 3-methylglutaconic aciduria that are tested on this panel are inherited in an autosomal recessive manner. Barth syndrome is inherited in an X-linked manner.

A recent newborn screening study in the U.S. has estimated that the prevalence of 3-methylglutaconic aciduria is 1 in 1,000,000 (PMID: 22766612).

This panel may be appropriate for:

  • patients with elevated 3-methylglutaconic acid on urine organic acid analysis

  1. Feuchtbaum, L, et al. Birth prevalence of disorders detectable through newborn screening by race/ethnicity. Genet. Med. 2012; 14(11):937-45. PMID: 22766612
  2. Ferreira, C, et al. Barth Syndrome. 2014 Oct 09. In: Pagon, RA, et al, editors. GeneReviews (Internet). University of Washington, Seattle; Available from: http://www.ncbi.nlm.nih.gov/books/NBK247162/ PMID: 25299040
  3. Wortmann, SB, et al. The 3-methylglutaconic acidurias: what's new?. J. Inherit. Metab. Dis. 2012; 35(1):13-22. PMID: 20882351
  4. Wortmann, SB, et al. CLPB Deficiency. 2016 Nov 22. In: Pagon, RA, et al, editors. GeneReviews(®) (Internet). University of Washington, Seattle. PMID: 27891836
  5. Wortmann, SB, et al. 3-Methylglutaconic aciduria--lessons from 50 genes and 977 patients. J. Inherit. Metab. Dis. 2013; 36(6):913-21. PMID: 23355087
  6. Anikster, Y, et al. Type III 3-methylglutaconic aciduria (optic atrophy plus syndrome, or Costeff optic atrophy syndrome): identification of the OPA3 gene and its founder mutation in Iraqi Jews. Am. J. Hum. Genet. 2001; 69(6):1218-24. PMID: 11668429
  7. Davey, KM, et al. Mutation of DNAJC19, a human homologue of yeast inner mitochondrial membrane co-chaperones, causes DCMA syndrome, a novel autosomal recessive Barth syndrome-like condition. J. Med. Genet. 2006; 43(5):385-93. PMID: 16055927
  8. Magner, M, et al. TMEM70 deficiency: long-term outcome of 48 patients. J. Inherit. Metab. Dis. 2015; 38(3):417-26. PMID: 25326274
  9. Schiff M, Ogier de Baulny H, Dionisi-Vici C. Inborn metabolic diseases: diagnosis and treatment. 6th ed. Heidelberg: Springer; 2016. Chapter 18, Branched-chain organic acidurias/acidaemias; p. 289–293.
  10. Rokicki, D, et al. 3-Methylglutaconic aciduria, a frequent but underrecognized finding in carbamoyl phosphate synthetase I deficiency. Clin. Chim. Acta. 2017; 471:95-100. PMID: 28526534

Assay and technical information

Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).

Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence in the transcript listed below. In addition, analysis covers the select non-coding variants specifically defined in the table below. Any variants that fall outside these regions are not analyzed. Any specific limitations in the analysis of these genes are also listed in the table below.

Based on validation study results, this assay achieves >99% analytical sensitivity and specificity for single nucleotide variants, insertions and deletions <15bp in length, and exon-level deletions and duplications. Invitae's methods also detect insertions and deletions larger than 15bp but smaller than a full exon but sensitivity for these may be marginally reduced. Invitae’s deletion/duplication analysis determines copy number at a single exon resolution at virtually all targeted exons. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. Certain types of variants, such as structural rearrangements (e.g. inversions, gene conversion events, translocations, etc.) or variants embedded in sequence with complex architecture (e.g. short tandem repeats or segmental duplications), may not be detected. Additionally, it may not be possible to fully resolve certain details about variants, such as mosaicism, phasing, or mapping ambiguity. Unless explicitly guaranteed, sequence changes in the promoter, non-coding exons, and other non-coding regions are not covered by this assay. Please consult the test definition on our website for details regarding regions or types of variants that are covered or excluded for this test. This report reflects the analysis of an extracted genomic DNA sample. In very rare cases, (circulating hematolymphoid neoplasm, bone marrow transplant, recent blood transfusion) the analyzed DNA may not represent the patient's constitutional genome.

Gene Transcript reference Sequencing analysis Deletion/Duplication analysis
AUH NM_001698.2
CLPB NM_030813.5
CPS1 NM_001875.4
DNAJC19 NM_145261.3
OPA3 NM_025136.3
SERAC1 NM_032861.3
TAZ NM_000116.4
TMEM70 NM_017866.5