Autosomal recessive leber hereditary optic neuropathy in a choroideremia carrier. A case report.

BACKGROUND: Leber hereditary optic neuropathy (LHON) is an inherited progressive optic neuropathy usually caused by mitochondrial DNA mutations. Recently, autosomal recessive (arLHON), which is caused by biallelic mutations in the DNAJC30 gene (usually c.152A > G), has been described. The onset of LHON before the age of 12 is uncommon and it is typically associated with a more variable clinical course and a more favorable visual prognosis than adult-onset LHON. MATERIALS AND METHODS: Detailed clinical findings of a female child with vision loss due to arLHON together with choroideremia (CHM) carrier state are presented. RESULTS: Genetic testing for the three most common mitochondrial LHON pathogenic variants was negative. On suspicion of arLHON, genetic testing was continued with the next-generation sequencing (NGS) of the nuclear DNA, identifying a homozygous pathogenic variant in DNAJC3°c.152A > G, p.(Tyr51Cys), but no alterations in the CHM gene. Idebenone treatment was started 4.5 months after the first evaluation. Clinical diagnosis of the CHM carrier state was confirmed by multiplex ligation-dependent probe amplification (MLPA) assay, which revealed a heterozygous deletion of all exons of the CHM. CONCLUSIONS: In children with acute or subacute, simultaneous, or sequential vision loss that is unresponsive to immunomodulatory treatment, LHON should be considered as a possible diagnosis. Our case emphasizes the diagnostic advantage of sequencing DNAJC30 in parallel with the mitochondrial DNA, especially in Eastern European descent patients. Genomic rearrangement testing should be considered for patients with a CHM carrier phenotype who have negative results on sequencing tests.

Carrier frequency of a common mutation of carnitine palmitoyltransferase 1A deficiency and long-term follow-up in Finland.

OBJECTIVE: To assess the long-term clinical course of carnitine palmitoyltransferase 1A (CPT1A) deficiency, caused by the c.1364A>C (p.K455T) mutation, and the carrier frequency of this mutation in Finland. STUDY DESIGN: This was a long-term follow-up of patients in whom the common mutation was detected. RESULTS: Between 1999 and 2010, 6 cases of CPT1A deficiency were diagnosed and treated with a high-carbohydrate, low-fat diet. The patients experienced their first symptoms during the first years of life, provoked by viral illness and/or fasting. The clinical features included hypoketotic hypoglycemia, hepatopathy, and loss of consciousness, ranging from transient unconsciousness to prolonged hyperlipidemic coma. Five cases carried a homozygous c.1364A>C (p.K455T) mutation, whereas 1 case had a compound c.1364A>C/c.1493A>C (p.Y498S) mutation. During dietary therapy, the patients had few transient decompensations. No carriers of mutation c.1364A>C were detected by minisequencing of 150 control samples. CONCLUSION: Even though CPT1A deficiency may be life-threatening and lead to prolonged coma, the long-term prognosis is good. A genotype-phenotype correlation implies that the mutations detected are disease-causing. Despite Finland's location close to the Arctic polar region, the carrier frequency of the c.1364A>C mutation in Finland is far lower than that of the variants found in Alaskan, Canadian, and Greenland native populations.

Carnitine palmitoyltransferase I and Acyl-CoA dehydrogenase 9 in retina: insights of retinopathy in mitochondrial trifunctional protein defects.

PURPOSE: Progressive pigment chorioretinopathy is a major long-term complication of mitochondrial trifunctional protein (MTP) defects, disorders of mitochondrial fatty acid beta-oxidation. To better understand the pathogenesis of the retinopathy component, the authors studied expression of the main regulatory protein of the beta-oxidation pathway, carnitine palmitoyltransferase (CPT) 1, and acyl-CoA dehydrogenase (ACAD) 9 in retinal sections and cultured cells. METHODS: Immunoblotting was performed with polyclonal antibodies to ACAD9 and the three isoforms of CPT1. In quantitative real-time PCR (QRT-PCR), predesigned gene-specific probes and primer sets for human CPT1 isoforms were used. In situ hybridization (ISH) and immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections of the rat and human eye. RESULTS: The predominant CPT1 mRNA types detected by QRT-PCR in cultured human retinal pigment epithelial cells were of the liver (CPT1A) and brain (CPT1C) isotypes. CPT1A and ACAD9 protein expression was found in cultured human and rat RPE and rat neural retinal precursor cells. ISH of rat retinal sections showed CPT1A and CPT1C expression in the retinal pigment epithelium (RPE), the inner nuclear layer, and the ganglion cell layer. CPT1A expression was also detected in the Müller cell microvilli, and CPT1C expression was detected in the photoreceptor inner segments. ACAD9 immunolabeling was detected in rat and human RPE, human photoreceptor inner segments, and ganglion cell layer. CONCLUSIONS: These findings imply that the mitochondrial fatty acid beta-oxidation pathway probably is active in metabolism of the RPE and certain neuroretinal cell types. Accumulation of 3-hydroxylated intermediates of long-chain fatty acids may contribute to the pathogenesis of retinopathy in MTP deficiencies.