omim.org

Online Mendelian Inheritance in Man (OMIM)

  • ️Tue Feb 20 2024

Cytogenetic location: 3q27.2 Genomic coordinates (GRCh38) : 3:185,190,624-185,254,049 (from NCBI)

TEXT

Description

The EHHADH gene encodes an enzyme involved in peroxisomal oxidation of fatty acids and is expressed in the proximal renal tubule (summary by Klootwijk et al., 2014).

Cloning and Expression

Hoefler et al. (1994) reported the full-length cDNA sequence of the enoyl-CoA-hydratase:3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme. The cDNA sequence spans 3,779 nucleotides with an open reading frame of 2,169 nucleotides.

In human kidney tissue, Klootwijk et al. (2014) found strong immunostaining of EHHADH in the terminal segments of the proximal tubule.

Gene Function

Zhao et al. (2010) showed that lysine acetylation is a prevalent modification in enzymes that catalyze intermediate metabolism in the human liver. Virtually every enzyme in glycolysis, gluconeogenesis, the tricarboxylic acid (TCA) cycle, the urea cycle, fatty acid metabolism, and glycogen metabolism was found to be acetylated in human liver tissue. The concentration of metabolic fuels, such as glucose, amino acids, and fatty acids, influenced the acetylation status of metabolic enzymes. Acetylation activated EHHADH in fatty acid oxidation and malate dehydrogenase (see 154200) in the TCA cycle, inhibited argininosuccinate lyase in the urea cycle, and destabilized phosphoenolpyruvate carboxykinase (261680) in gluconeogenesis. Zhao et al. (2010) concluded that acetylation plays a major role in metabolic regulation.

Biochemical Features

Bahnson et al. (2002) determined the crystal structure of rat enoyl-CoA hydratase (Ech) in complex with a thiolester substrate at a resolution of 2.3 angstroms. Each crystallographic asymmetric unit contained 1 physiologic hexamer of 168 kD consisting of 2 stacked trimers of 3 identical monomers of 28 kD each. Each subunit of the trimers bound to a substrate molecule. In addition, the structure contained a single catalytic water molecule, and the 3 atoms from the water molecule were set up to add to the double bond of the substrate to form the hydrated product.

Mapping

By fluorescence in situ hybridization, Hoefler et al. (1994) localized the EHHADH gene to chromosome 3q26.3-q28.

Molecular Genetics

In affected members of a family with autosomal dominant Fanconi renotubular syndrome-3 (FRTS3; 615605), originally reported by Tolaymat et al. (1992), Klootwijk et al. (2014) identified a heterozygous mutation in the EHHADH gene (E3K; 607037.0001). The mutation was found by genomewide linkage analysis followed by Sanger sequencing of candidate genes in the region. Transfection of the mutation into several cell lines, including a renal proximal tubular cell line, showed that the mutant protein localized to mitochondria as well as to peroxisomes, whereas wildtype EHHADH localized only to peroxisomes. Transfected renal tubular cells showed a defect in the transepithelial transport of fluids, with an inability to maintain fluid-filled domes in confluent monolayers, as well as a defect in luminal to basolateral transport of a glucose surrogate. These changes were associated with a defect in mitochondrial respiration and impaired ATP production. Mutant EHHADH coimmunoprecipitated with mitochondrial HADHA (600890) and HADHB (143450), which likely impaired mitochondrial function. These findings, combined with the lack of renal or mitochondrial dysfunction in Ehhadh-null mice, were consistent with a dominant-negative toxic effect of the mutant EHHADH protein rather than haploinsufficiency. The patients had onset in early childhood of metabolic acidosis, glucosuria, phosphaturia, aminoaciduria, and proteinuria, but did not develop renal failure. Some patients had rickets and poor growth. Klootwijk et al. (2014) noted that proximal tubular cells use fatty acid oxidation as the predominant energy source, and that proper mitochondrial function is required for renal tubular reabsorption.

History

A number of patients with presumed L-bifunctional protein deficiency were later found to have D-bifunctional protein deficiency; see 261515.

Animal Model

Qi et al. (1999) generated Lpb-null mice. Mutant mice were viable and fertile and exhibited no detectable gross phenotypic defects. The only defect was a blunting of peroxisome proliferative response upon challenge with a peroxisome proliferator. The absence of appreciable changes in lipid metabolism indicated that enoyl-CoAs, generated in the classical system in Lpb-null mice, were diverted to the D-hydroxy-specific system for metabolism by Dbp (HSD17B4; 601860).

Klootwijk et al. (2014) found that Ehhadh-null mice did not show aminoaciduria, glucosuria, or phosphaturia, suggesting normal renal function. Mutant mice also had no evidence of mitochondrial dysfunction.

ALLELIC VARIANTS 1 Selected Example):

.0001   FANCONI RENOTUBULAR SYNDROME 3 (1 family)

EHHADH, GLU3LYS
SNP: rs398124646, ClinVar: RCV000082871

In affected members of a family with autosomal dominant Fanconi renotubular syndrome-3 (FRTS3; 615605) originally reported by Tolaymat et al. (1992), Klootwijk et al. (2014) identified a heterozygous c.7G-A transition in exon 1 of the EHHADH gene, resulting in a glu3-to-lys (E3K) substitution at a highly conserved residue. The substitution predicted the creation of an N-terminal mitochondrial targeting motif. The mutation was found by genomewide linkage analysis followed by Sanger sequencing of candidate genes in the region. The mutation segregated with the disorder in the family, and was not present in the dbSNP (build 137) or 1000 Genomes Project databases, or in 200 control alleles. Transfection of the mutation into several cell lines, including a renal proximal tubular cell line, showed that the mutant protein localized to mitochondria as well as to peroxisomes, whereas wildtype EHHADH localized only to peroxisomes. Electron microscopy of cells with the mutation showed no mitochondrial morphologic abnormalities. However, transfected renal tubular cells showed a defect in the transepithelial transport of fluids, with an inability to maintain fluid-filled domes in confluent monolayers. Transfected cells also showed a defect in luminal to basolateral transport of a glucose surrogate. These changes were associated with a defect in mitochondrial respiration and impaired ATP production. Mutant EHHADH coimmunoprecipitated with mitochondrial HADHA (600890) and HADHB (143450), which likely impaired mitochondrial function. These findings, combined with the lack of renal or mitochondrial dysfunction in Ehhadh-null mice, were consistent with a dominant-negative toxic effect of the mutant EHHADH protein rather than haploinsufficiency.

REFERENCES

  1. Bahnson, B. J., Anderson, V. E., Petsko, G. A. Structural mechanism of enoyl-CoA hydratase: three atoms from a single water are added in either an E1cb stepwise or concerted fashion. Biochemistry 41: 2621-2629, 2002. [PubMed: 11851409] [Full Text: https://doi.org/10.1021/bi015844p]

  2. Hoefler, G., Forstner, M., McGuinness, M. C., Hulla, W., Hiden, M., Krisper, P., Kenner, L., Ried, T., Lengauer, C., Zechner, R., Moser, H. W., Chen, G. L. cDNA cloning of the human peroxisomal enoyl-CoA hydratase:3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme and localization to chromosome 3q26.3-3q28: a free left Alu arm is inserted in the 3-prime noncoding region. Genomics 19: 60-67, 1994. [PubMed: 8188243] [Full Text: https://doi.org/10.1006/geno.1994.1013]

  3. Klootwijk, E. D., Reichold, M., Helip-Wooley, A., Tolaymat, A., Broeker, C., Robinette, S. L., Reinders, J., Peindl, D., Renner, K., Eberhart, K., Assmann, N., Oefner, P. J., and 27 others. Mistargeting of peroxisomal EHHADH and inherited renal Fanconi's syndrome. New Eng. J. Med. 370: 129-138, 2014. [PubMed: 24401050] [Full Text: https://doi.org/10.1056/NEJMoa1307581]

  4. Qi, C., Zhu, Y., Pan, J., Usuda, N., Maeda, N., Yeldandi, A. V., Rao, M. S., Hashimoto, T., Reddy, J. K. Absence of spontaneous peroxisome proliferation in enoyl-CoA hydratase/L-3-hydroxyacyl-CoA dehydrogenase-deficient mouse liver: further support for the role of fatty acyl CoA oxidase in PPAR-alpha ligand metabolism. J. Biol. Chem. 274: 15775-15780, 1999. [PubMed: 10336479] [Full Text: https://doi.org/10.1074/jbc.274.22.15775]

  5. Tolaymat, A., Sakarcan, A., Neiberger, R. Idiopathic Fanconi syndrome in a family. Part I. Clinical aspects. J. Am. Soc. Nephrol. 2: 1310-1317, 1992. [PubMed: 1627757] [Full Text: https://doi.org/10.1681/ASN.V281310]

  6. Zhao, S., Xu, W., Jiang, W., Yu, W., Lin, Y., Zhang, T., Yao, J., Zhou, L., Zeng, Y., Li, H., Li, Y., Shi, J., and 10 others. Regulation of cellular metabolism by protein lysine acetylation. Science 327: 1000-1004, 2010. [PubMed: 20167786] [Full Text: https://doi.org/10.1126/science.1179689]