Serum very long-chain fatty acids (VLCFA) levels as predictive biomarkers of diseases severity and probability of survival in peroxisomal disorders.

CONCLUSION: VLCFA levels correlate with the severity of the clinical course of ZS, DBP and mild ZSD. The best predictive value for estimating the projected disease severity and survival time is a concentration of C26:0.

Mild Zellweger syndrome due to functionally confirmed novel PEX1 variants.

Zellweger spectrum disorders (ZSD) constitute a group of rare autosomal recessive disorders characterized by a defect in peroxisome biogenesis due to mutations in one of 13 PEX genes. The broad clinical heterogeneity especially in late-onset presenting patients and a mild phenotype complicates and delays the diagnostic process. Here, we report a case of mild ZSD, due to novel PEX1 variants. The patient presented with an early hearing loss, bilateral cataracts, and leukodystrophy on magnetic resonance (MR) images. Normal results of serum very-long-chain fatty acids (VLCFA) and phytanic acid were found. Molecular diagnostics were performed to uncover the etiology of the clinical phenotype. Using whole exome sequencing, there have been found two variants in the PEX1 gene-c.3450T>A (p.Cys1150*) and c.1769T>C (p.Leu590Pro). VLCFA measurement in skin fibroblasts and C26:0-lysoPC in dried blood spot therefore was performed. Both results were in line with the diagnosis of ZSD. To conclude, normal results of routine serum VLCFA and branched-chain fatty acid measurement do not exclude mild forms of ZSD. The investigation of C26:0-lysoPC should be included in the diagnostic work-up in patients with cataract, hearing loss, and leukodystrophy on MR images suspected to suffer from ZSD.

Dominant ELOVL1 mutation causes neurological disorder with ichthyotic keratoderma, spasticity, hypomyelination and dysmorphic features.

BACKGROUND: Ichthyosis and neurological involvement occur in relatively few known Mendelian disorders caused by mutations in genes relevant both for epidermis and neural function. OBJECTIVES: To identify the cause of a similar phenotype of ichthyotic keratoderma, spasticity, mild hypomyelination (on MRI) and dysmorphic features (IKSHD) observed in two unrelated paediatric probands without family history of disease. METHODS: Whole exome sequencing was performed in both patients. The functional effect of prioritised variant in ELOVL1 (very-long-chain fatty acids (VLCFAs) elongase) was analysed by VLCFA profiling by gas chromatography-mass spectrometry in stably transfected HEK2932 cells and in cultured patient's fibroblasts. RESULTS: Probands shared novel heterozygous ELOVL1 p.Ser165Phe mutation (de novo in one family, while in the other family, father could not be tested). In transfected cells p.Ser165Phe: (1) reduced levels of FAs C24:0-C28:0 and C26:1 with the most pronounced effect for C26:0 (P=7.8×10-6 vs HEK293 cells with wild type (wt) construct, no difference vs naïve HEK293) and (2) increased levels of C20:0 and C22:0 (P=6.3×10-7, P=1.2×10-5, for C20:0 and C22:0, respectively, comparison vs HEK293 cells with wt construct; P=2.2×10-7, P=1.9×10-4, respectively, comparison vs naïve HEK293). In skin fibroblasts, there was decrease of C26:1 (P=0.014), C28:0 (P=0.001) and increase of C20:0 (P=0.033) in the patient versus controls. There was a strong correlation (r=0.92, P=0.008) between the FAs profile of patient's fibroblasts and that of p.Ser165Phe transfected HEK293 cells. Serum levels of C20:0-C26:0 FAs were normal, but the C24:0/C22:0 ratio was decreased. CONCLUSION: The ELOVL1 p.Ser165Phe mutation is a likely cause of IKSHD.

Mild Zellweger syndrome due to a novel PEX6 mutation: correlation between clinical phenotype and in silico prediction of variant pathogenicity.

Zellweger syndrome (ZS) is a consequence of a peroxisome biogenesis disorder (PBD) caused by the presence of a pathogenic mutation in one of the 13 genes from the PEX family. ZS is a severe multisystem condition characterized by neonatal appearance of symptoms and a shorter life. Here, we report a case of ZS with a mild phenotype, due to a novel PEX6 gene mutation. The patient presented subtle craniofacial dysmorphic features and slightly slower psychomotor development. At the age of 2 years, he was diagnosed with adrenal insufficiency, hypoacusis, and general deterioration. Magnetic resonance imaging showed a symmetrical hyperintense signal in the frontal and parietal white matter. Biochemical tests showed elevated liver transaminases, elevated serum very long chain fatty acids, and phytanic acid. After the death of the child at the age of 6 years, molecular diagnostics were continued in order to provide genetic counseling for his parents. Next generation sequencing (NGS) analysis with the TruSight One™ Sequencing Panel revealed a novel homozygous PEX6 p.Ala94Pro mutation. In silico prediction of variant severity suggested its possible benign effect. To conclude, in the milder phenotypes, adrenal insufficiency, hypoacusis, and leukodystrophy together seem to be pathognomonic for ZS.

The Role of MR Imaging in the Assessment of Clinical Outcomes in Children with X-Linked Adrenoleukodystrophy after Allogeneic Haematopoietic Stem Cell Transplantation.

BACKGROUND: The aim of the study was to analyse MR images of the brain, including advanced MR techniques, such as single voxel spectroscopy (MRS) and diffusion tensor imaging (DTI), in children with X-linked adrenoleukodystrophy (X-ALD) before and after haematopoietic stem cell transplantation (HSCT) and to establish the imaging criteria which may be helpful in the assessment of disease staging, qualification to HSCT and follow-up. MATERIAL/METHODS: Seven boys, aged 5-10 years, (mean 8.14 years) with biochemically proved X-ALD, underwent plain MR imaging with a 1.5 T unit before and after HSCT. Structural images were analyzed using an MRI severity scale (Loes scale). In one patient the follow-up examinations included MRS with the assessment of metabolite ratios (NAA/Cr, Cho/Cr, mI/Cr), as well as DTI with evaluation of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in several white matter tracts. RESULTS: Two boys had an MRI severity score before HSCT equal to <8 points, and after HSCT they showed no clinical or radiological progression. In 5 patients with a higher severity score (from 8 to 16 points, mean 10.9) before HSCT, clinical and radiological progression was observed (MRI severity score from 17 to 25 points, mean 20.9). Follow-up advanced MRI techniques in one boy showed metabolic alterations, as well as decreased FA and ADC values in all evaluated areas. CONCLUSIONS: Children at an early stage of X-ALD (below 8 points in MRI severity scale) are more likely to benefit from HSCT. DTI and MRS seem to be more useful imaging methods to assess the progression of X-ALD.

Serum very-long-chain fatty acids levels determined by gas chromatography in the diagnosis of peroxisomal disorders in Poland.

Peroxisomal disorders are a large group of genetically determined metabolic diseases in which the biogenesis of peroxisomes is defective or there is a deficiency of only a single enzyme activity or substrate transporter. The objective of this report is to present ten years of experience in the diagnostics of peroxisomal disorders in Poland. Very-long-chain fatty acid (VLCFA) levels as a biomarker for peroxisomal defects were determined by gas chromatography in 1264 subjects with suspicion of peroxisome disease. Peroxisome biogenesis disorders (PBD) were diagnosed in 8 patients, bifunctional protein deficiency in 3 and X-linked adrenoleukodystrophy (X-ALD/AMN) in 127 hemi- or heterozygotes. The frequency of PBD was estimated as 0.20 : 100 000, and that of X-ALD/AMN 2.9 : 100,000 in Poland. Mean total delay time (onset of symptoms and diagnosis) for X-ALD/AMN was 2.2 years (range 0.25-13). High correlation of serum C26:0 concentration and survival for PBD patient (r2 = 0.822; p < 0.001) was found.

Cerebral childhood and adolescent X-linked adrenoleukodystrophy. Clinical presentation, neurophysiological, neuroimaging and biochemical investigations.

Clinical, neurophysiological, neuroimaging and biochemical studies were performed in five boys with childhood and adolescent form of cerebral X-ALD, which is a very rare disease in developmental age. In all patients, rapidly progressive spasticity, ataxia and mental deterioration were found. Seizures occurred in four of them. Additionally, visual and hearing impairment were observed in four and three patients respectively. Adrenal insufficiency was also diagnosed in four cases. MR revealed extensive demyelination located mainly symmetrically in the parieto-occipital areas, in one patient in whom asymmetrical lesions in that region were found. All patients had abnormal visual, brainstem and somatosensory evoked potentials recording, reflecting the central demyelination occurring in X-ALD. The clinical diagnosis in every case was confirmed by the significantly elevated concentration of very long chain fatty acids (VLCFA) measured in plasma in comparison to normal values.