Pervasive inflammatory activation in patients with deficiency in very-long-chain acyl-coA dehydrogenase (VLCADD).

OBJECTIVES: Very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a disorder of fatty acid oxidation. Symptoms are managed by dietary supplementation with medium-chain fatty acids that bypass the metabolic block. However, patients remain vulnerable to hospitalisations because of rhabdomyolysis, suggesting pathologic processes other than energy deficit. Since rhabdomyolysis is a self-destructive process that can signal inflammatory/immune cascades, we tested the hypothesis that inflammation is a physiologic dimension of VLCADD. METHODS: All subjects (n = 18) underwent informed consent/assent. Plasma cytokine and cytometry analyses were performed. A prospective case analysis was carried out on a patient with recurrent hospitalisation. Health data were extracted from patient medical records. RESULTS: Patients showed systemic upregulation of nine inflammatory mediators during symptomatic and asymptomatic periods. There was also overall abundance of immune cells with high intracellular expression of IFNγ, IL-6, MIP-1ß (CCL4) and TNFα, and the transcription factors p65-NFκB and STAT1 linked to inflammatory pathways. A case analysis of a patient exhibited already elevated plasma cytokine levels during diagnosis in early infancy, evolving into sustained high systemic levels during recurrent rhabdomyolysis-related hospitalisations. There were corresponding activated leukocytes, with higher intracellular stores of inflammatory molecules in monocytes compared to T cells. Exposure of monocytes to long-chain free fatty acids recapitulated the cytokine signature of patients. CONCLUSION: Pervasive plasma cytokine upregulation and pre-activated immune cells indicate chronic inflammatory state in VLCADD. Thus, there is rationale for practical implementation of clinical assessment of inflammation and/or translational testing, or adoption, of anti-inflammatory intervention(s) for personalised disease management.

Successful orthotopic heart transplantation in CPTII deficiency.

Carnitine palmitoyl transferase II (CPT II) catalyzes the release of activated long-chain fatty acids from acylcarnitines into mitochondria for subsequent fatty acid oxidation. Depending on residual enzyme activity, deficiency of this enzyme leads to a spectrum of symptoms from early onset hypoglycemia, hyperammonemia, cardiomyopathy and death to onset of recurrent rhabdomyolysis in adolescents and young adults. We present a case of successful orthotopic heart transplantation in a patient with severe infantile onset cardiomyopathy due to CPT II deficiency identified through newborn screening. Excellent cardiac function is preserved 12 years post-transplantation; however, the patient has developed intermittent episodes of hyperammonemia and rhabdomyolysis later in childhood and early adolescence readily resolved with intravenous glucose. Successful heart transplant in this patient demonstrates the feasibility of this management option in patients with even severe forms of long chain fatty acid oxidation disorders.

Long-term major clinical outcomes in patients with long chain fatty acid oxidation disorders before and after transition to triheptanoin treatment--A retrospective chart review.

BACKGROUND: Long chain fatty acid oxidation disorders (LC-FAODs) are caused by defects in the metabolic pathway that converts stored long-chain fatty acids into energy, leading to a deficiency in mitochondrial energy production during times of physiologic stress and fasting. Severe and potentially life threatening clinical manifestations include rhabdomyolysis, hypoglycemia, hypotonia/weakness, cardiomyopathy and sudden death. We present the largest cohort of patients to date treated with triheptanoin, a specialized medium odd chain (C7) triglyceride, as a novel energy source for the treatment of LC-FAOD. METHODS: This was a retrospective, comprehensive medical record review study of data from 20 of a total 24 patients with LC-FAOD who were treated for up to 12.5 years with triheptanoin, as part of a compassionate use protocol. Clinical outcomes including hospitalization event rates, number of hospitalization days/year, and abnormal laboratory values were determined for the total period of the study before and after triheptanoin treatment, as well as for specified periods before and after initiation of triheptanoin treatment. Other events of interest were documented including rhabdomyolysis, hypoglycemia, and cardiomyopathy. RESULTS: LC-FAOD in these 20 subjects was associated with 320 hospitalizations from birth to the end date of study. The mean hospitalization days/year decreased significantly by 67% during the period after triheptanoin initiation (n=15; 5.76 vs 17.55 vs; P=0.0242) and a trend toward a 35% lower hospitalization event rate was observed in the period after triheptanoin initiation compared with the before-treatment period (n=16 subjects >6 months of age; 1.26 vs 1.94; P=0.1126). The hypoglycemia event rate per year in 9 subjects with hypoglycemia problems declined significantly by 96% (0.04 vs 0.92; P=0.0091) and related hospitalization days/year were also significantly reduced (n=9; 0.18 vs 8.42; P=0.0257). The rhabdomyolysis hospital event rate in 11 affected subjects was similar before and after treatment but the number of hospitalization days/year trended lower in the period after triheptanoin initiation (n=9; 2.36 vs 5.94; P=0.1224) and peak CK levels trended toward a 68% decrease from 85,855 to 27,597 units in 7 subjects with reported peak CK values before and after treatment (P=0.1279). Triheptanoin was generally well tolerated. Gastrointestinal symptoms were the most commonly reported side effects. CONCLUSIONS: This retrospective study represents the largest analysis reported to date of treatment of LC-FAOD with triheptanoin. The data suggest that triheptanoin improves the course of disease by decreasing the incidence and duration of major clinical manifestations and should be the focus of prospective investigations. Significant heterogeneity in the routine clinical care provided to subjects during the periods studied and the natural variation of clinical course of LC-FAODs with time emphasize the need of additional study of the use of triheptanoin.

Molecular and cellular pathology of very-long-chain acyl-CoA dehydrogenase deficiency.

BACKGROUND: Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD) is diagnosed in the US through newborn screening (NBS). NBS often unequivocally identifies affected individuals, but a growing number of variant patterns can represent mild disease or heterozygous carriers. AIMS: To evaluate the validity of standard diagnostic procedures for VLCADD by using functional in vitro tools. METHODS: We retrospectively investigated 13 patient samples referred to our laboratory because of a suspicion of VLCADD but with some uncertainty to the diagnosis. All 13 patients were suspected of having VLCADD either because of abnormal NBS or suggestive clinical findings. ACADVL genomic DNA sequencing data were available for twelve of them. Ten of the patients had an abnormal NBS suggestive of VLCADD, with three samples showing equivocal results. Three exhibited suggestive clinical findings and blood acylcarnitine profile (two of them had a normal NBS and the third one was unscreened). Assay of VLCAD activity and immunoblotting or immunohistologic staining for VLCAD were performed on fibroblasts. Prokaryotic mutagenesis and expression studies were performed for nine uncharacterized ACADVL missense mutations. RESULTS: VLCAD activity was abnormal in fibroblast cells from 9 patients (8 identified through abnormal NBS, 1 through clinical symptoms). For these 9 patients, immunoblotting/staining showed the variable presence of VLCAD; all but one had two mutated alleles. Two patients with equivocal NBS results (and a heterozygous genotype) and the two patients with normal NBS exhibited normal VLCAD activity and normal VLCAD protein on immunoblotting/staining thus ruling out VLCAD deficiency. Nine pathogenic missense mutations were characterized with prokaryotic expression studies and showed a decrease in enzyme activity and variable stability of VLCAD antigen. CONCLUSIONS: These results emphasize the importance of functional investigation of abnormal NBS or clinical testing suggestive but not diagnostic of VLCADD. A larger prospective study is necessary to better define the clinical and metabolic ramifications of the defects identified in such patients.

Genotype-phenotype analysis of 4q deletion syndrome: proposal of a critical region.

Chromosome 4q deletion syndrome (4q- syndrome) is a rare condition, with an estimated incidence of 1 in 100,000. Although variable, the clinical spectrum commonly includes craniofacial, developmental, digital, skeletal, and cardiac involvement. Data on the genotype-phenotype correlation within the 4q arm are limited. We present detailed clinical and genetic information by array CGH on 20 patients with 4q deletions. We identified a patient who has a ∼465 kb deletion (186,770,069-187,234,800, hg18 coordinates) in 4q35.1 with all clinical features for 4q deletion syndrome except for developmental delay, suggesting that this is a critical region for this condition and a specific gene responsible for orofacial clefts and congenital heart defects resides in this region. Since the patients with terminal deletions all had cleft palate, our results provide further evidence that a gene associated with clefts is located on the terminal segment of 4q. By comparing and contrasting our patients' genetic information and clinical features, we found significant genotype-phenotype correlations at a single gene level linking specific phenotypes to individual genes. Based on these data, we constructed a hypothetical partial phenotype-genotype map for chromosome 4q which includes BMP3, SEC31A, MAPK10, SPARCL1, DMP1, IBSP, PKD2, GRID2, PITX2, NEUROG2, ANK2, FGF2, HAND2, and DUX4 genes.

A copy number variation morbidity map of developmental delay.

To understand the genetic heterogeneity underlying developmental delay, we compared copy number variants (CNVs) in 15,767 children with intellectual disability and various congenital defects (cases) to CNVs in 8,329 unaffected adult controls. We estimate that ∼14.2% of disease in these children is caused by CNVs >400 kb. We observed a greater enrichment of CNVs in individuals with craniofacial anomalies and cardiovascular defects compared to those with epilepsy or autism. We identified 59 pathogenic CNVs, including 14 new or previously weakly supported candidates, refined the critical interval for several genomic disorders, such as the 17q21.31 microdeletion syndrome, and identified 940 candidate dosage-sensitive genes. We also developed methods to opportunistically discover small, disruptive CNVs within the large and growing diagnostic array datasets. This evolving CNV morbidity map, combined with exome and genome sequencing, will be critical for deciphering the genetic basis of developmental delay, intellectual disability and autism spectrum disorders.