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Metabolic Diseases
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
Stephanie Grünewald, Alex Broomfield, Callum Wilson
Peroxisomal functions include the beta-oxidation of VLCFAs, pristanic acid and bile acid synthesis and others. PBDs are caused by a failure of protein (enzyme) import into the peroxisome, encoded by various PEX genes. A variety of gene defects can result in the same phenotype (locus heterogeneity) and yet the various phenotypes can also be allelic. In addition there are single enzyme peroxisomal disorders that can give rise to an infantile Refsum-like phenotype. All the conditions are inherited in an autosomal recessive manner.
Two siblings with Heimler syndrome caused by PEX1 variants: follow-up of ophthalmologic findings
Published in Ophthalmic Genetics, 2021
Dorien Herijgers, Ellen Denayer, Irina Balikova, Peter Witters, Julie Jacob, Ingele Casteels
Subject 1 has delayed development of gross motor performance since he only started walking at the age of 18 months. According to the parents, his intelligence quotient (IQ)is reported to be below average, but we do not have access to the exact results. He follows special education adapted for children with hearing problems. Biochemical screening for other evidence of peroxisomal dysfunction demonstrated no abnormalities, more specifically the values for pipecolic acid and very-long-chain fatty acid (VLCFA) were normal. Subject 2 has a failure to thrive with weight and height 2 standard deviations (SD) below the mean. Her IQ is reported to be below average but records were not available for review. In contrast to subject 1, biochemical screening for peroxisomal dysfunction revealed increased levels of pipecolic acid (12,3µ/L) and VLCFA (pristanic acid, phytanic acid and C26) which is compatible with peroxisomal dysfunction. These findings are remarkable since most reported patients with Heimler syndrome do not have biochemical evidence of a peroxisome biogenesis disorder (PBD) (3).
Novel retinal findings in peroxisomal biogenesis disorders
Published in Ophthalmic Genetics, 2018
B. E. O’Bryhim, B. A. Kozel, G. T. Lueder
The patient was referred to geneticsthe pediatric genetics service. Very long chain fatty acid analysis revealed elevated C26:0, C26:1 and pristanic acid levels as well as elevated C24/C22 and C26/C22 ratios consistent with peroxisomal biogenesis disorders. Red blood cell plasmalogen testing revealed mildly decreased C16:0 dimethylacetal (DMA)/C16:0 fatty acid and C18:0 DMA/C18:0 fatty acid levels. Genetic testing of PEX1 exons 13, 15, 18, and 19 revealed compound heterozygous mutations of c.2097 dup T (a frameshift mutation with premature stop codon) and a c.2528 G > A (p.Gly843Asp) missense mutation, confirming her diagnosis. Due to agreement of the biochemical and genetic data, parental testing to assess cis/trans conformation of the alleles was not performed.
A review on neuropharmacological role of erucic acid: an omega-9 fatty acid from edible oils
Published in Nutritional Neuroscience, 2022
J. B. Senthil Kumar, Bhawna Sharma
The formed reactive aldehyde covalently binds with the post-translational modified proteins at the specific amino acid via Michael reaction. The protein-aldehyde adduct is toxic to the cellular components [62]. Lipid peroxidation and its relationship between neurodegeneration is extensively studied since from the last two decades [63]. Phytanic acid is a methyl branched chain fatty acid that cannot be oxidised by mitochondria, instead it undergoes α-oxidation in the peroxisomes to pristanic acid which further metabolised through β-oxidation pathway [64]. Accumulation of phytanic acid results in neurological damage as observed in peroxisomal disorder called Refsum’s disease [65].