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Primary carnitine deficiency in two sisters with intractable epilepsy and reversible metabolic cardiomyopathy: Two case reports

ABSTRACT: Primary carnitine deficiency (PCD) is a disorder of the carnitine cycle that results in defective fatty acid oxidation. When carnitine cannot be transported into the cells, fatty acid oxidation is impaired, resulting a variety of symptoms, such as chronic muscle weakness, cardiomyopathy, hypoglycemia and liver dysfunction. The clinical manifestations and outcomes of different cases with PCD vary among patients. The present case report focused on two sisters with PCD. The younger sister presented with intractable epilepsy, and the older sister presented with reversible metabolic cardiomyopathy. Potential mutations in the SLC22A5 gene were investigated within the family, and a nonsense mutation [c.760C>T (p.R254X)] was identified in four family members. The two sisters harbored homozygous mutations, whereas their parents presented heterozygous mutations. Metabolic disease screening revealed low plasma free carnitine levels (<5 µmol/l) in the two sisters. The plasma free carnitine levels of their parents were normal, and they were asymptomatic. PCD in the two patients was managed using oral levocarnitine. The metabolic cardiomyopathy of the older sister improved following 3 months of treatment. However, the epilepsy of the younger sister was recurrent with oral antiepileptic therapy lasting one year and eight months, and epilepsy was finally controlled following right cerebral resection. The present case report demonstrated that the clinical manifestations presented by patients with PCD within the same family were different. The results indicated that treatment with levocarnitine supplementation should be initiated as soon as possible before irreversible organ damage occurs. In addition, metabolic decompensation and cardiac muscle functions were improved following carnitine supplementation. The resection of the severely diseased unilateral brain combined with carnitine supplementation and antiepileptic therapy may be an effective treatment for PCD with intractable epilepsy complications.

SUBMITTER: Yang X

PROVIDER: S-EPMC7523286 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Project description:Carnitine is essential for the transfer of long-chain fatty acids across the mitochondrial membrane for subsequent beta-oxidation. A defect in the high-affinity carnitine transporter OCTN2 causes autosomal recessive primary carnitine deficiency that can present with hypoketotic hypoglycemia, mainly in infancy or cardiomyopathy. Heterozygotes for primary carnitine deficiency can have mildly reduced plasma carnitine levels and can develop benign cardiac hypertrophy. In animal models, heterozygotes for this disease have a higher incidence of cardiomyopathy with aging. This study tested whether heterozygosity for primary carnitine deficiency was associated with cardiomyopathy. The frequency of mutations in the SLC22A5 gene encoding the OCTN2 carnitine transporter was determined in 324 patients with cardiomyopathy and compared to that described in the normal population. Missense variations identified in normal controls and patients with cardiomyopathy were expressed in Chinese Hamster Ovary cells to confirm a functional effect. Exons 2-10 of the SLC22A5 gene were amplified by PCR in the presence of LCGreen I and analyzed by dye-binding/high-resolution thermal denaturation. Exon 1 of the gene was sequenced in all patients. Heterozygosity for a few variants (L144F, T264M, I312V, E317K, and R488H) was found in 6/324 patients with cardiomyopathy. Expression of these variants in CHO cells indicated that T264M decreased, E317K increased, while L144F, I312V, and R488H did not significantly affect carnitine transport. Expression in CHO cells of all the variants identified in a normal population indicated that only two had a functional effect (L17F and Y449D), while L144F, V481I, V481F, M530V, and P549S did not change significantly carnitine transport. The frequency of variants affecting carnitine transport was 2/324 patients with cardiomyopathy (0.61%) not significantly different from frequency of 3/270 (1.11%) in the general population. These results indicate that heterozygosity for primary carnitine deficiency is not more frequent in patients with unselected types of cardiomyopathy and is unlikely to be an important cause of cardiomyopathy in humans.

Project description:RationaleCarnitine-acylcarnitine translocate deficiency (CACTD) is a rare and life-threatening, autosomal recessive disorder of fatty acid β-oxidation characterized by hypoketotic hypoglycemia, hyperammonemia, cardiomyopathy, liver dysfunction, and muscle weakness; culminating in early death. To date, CACTD cases screened from the Chinese mainland population, especially patient with compound heterozygote with c.199-10T>G and a novel c.1A>G mutation in the SLC25A20 gene has never been described.Patient concernsHerein, we report 2 neonatal cases of CACTD identified from the mainland China. These 2 patients were presented with severe metabolic crisis and their clinical conditions deteriorate rapidly and both died of cardiorespiratory collapse in the first week of life. We present the clinical and biochemical features of 2 probands and a brief literature review of previously reported CACTD cases with the c.199-10T>G mutation.DiagnosesThe acylcarnitine profiles by tandem-mass-spectrometry and the mutation analysis of SLC25A20 gene confirmed the diagnosis of CACTD in both patients. Mutation analysis demonstrated that patient No. 1 was homozygous for c.199-10T>G mutation, while patient No. 2 was a compound heterozygote for 2 mutations, a maternally-inherited c.199-10T>G and a paternally-inherited, novel c.1A>G mutation.InterventionsBoth patients were treated with an aggressive treatment regimen include high glucose and arginine infusion, respiratory, and circulatory support.OutcomesThe first proband died 3 days after delivery due to sudden cardiac arrest. The second patient's clinical condition, at one time, was improved by high glucose infusion, intravenous arginine, and circulatory support. However, the patient failed to wean from mechanical ventilation. Unfortunately, her parents refused further treatment due to fear of financial burdens. The patient died of congestive heart failure in the 6th day of life.LessonsWe report the first 2 cases of CACTD identified from the mainland China. Apart from a founder mutation c.199-10T>G, we identified a novel c.1A>G mutation. Patients with CACTD with a genotype of c.199-10T>G mutation usually presents with a severe clinical phenotype. Early recognition and appropriate treatment is crucial in this highly lethal disorder. This case series highlights the importance of screening for metabolic diseases including CACTD in cases of sudden infant death and unexplained abrupt clinical deterioration in the early neonatal period.

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Primary carnitine deficiency in two sisters with intractable epilepsy and reversible metabolic cardiomyopathy: Two case reports

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