Novel mutations associated with carnitine-acylcarnitine translocase and carnitine palmitoyl transferase 2 deficiencies in Malaysia

Low C0 and normal C16 and C18:1 masking the diagnosis of carnitine palmitoyltransferase II deficiency including a novel CPT2 variant: A case report

The cases were a pair of siblings with a carnitine palmitoyltransferase (CPT2) deficiency detected by tandem mass spectrometry. Their C16 and C18:1 levels were both within the normal range, while C0 was low, and the (C16+C18:1)/C2 ratio was high. Following genetic testing, a novel CPT2 gene mutation was identified in both patients. The male patient had a normal growth rate during 5 years of follow-up after treatment. By contrast, the female patient did not take l-carnitine supplements and died after an infectious disease-associated illness when she was 1 year old. These data emphasize the need to raise awareness about CPT2 deficiency so as to correctly diagnose and accurately manage the disease.

Metabolomic analysis for asymptomatic hyperuricemia and gout based on a combination of dried blood spot sampling and mass spectrometry technology

BACKGROUND

Gout is the most common inflammatory arthritis and closely related to metabolic syndrome, leading to excruciating pain and the decline in quality of patients' life. However, the pathogenesis of gout is still unclear, and novel biomarkers are demanded for the early prediction and diagnosis of gout.

OBJECTIVE

This study aimed at profiling the dysregulated metabolic pathways in asymptomatic hyperuricemia (AHU) and gout and elucidating the associations between AHU, gout and metabolomics, which may aid in performing gout screening.

METHODS

A total of 300 participants, including 114 healthy controls, 92 patients with AHU, and 94 patients with gout, were analyzed by using a combination of dried blood spot (DBS) sampling and mass spectrometry (MS) technology. Multiple algorithms were applied to characterize altered metabolic profiles in AHU and gout. The mainly altered metabolites were identified by random forest analysis.

RESULTS

There were significant differences in AHU and gout compared with control group. The altered metabolites were involved in oxidation of fatty acids, carnitine synthesis, urea cycle, and amino acid metabolism in AHU and gout. Random forest classification of 16 metabolites yielded 3 important features to distinguish gout from AHU.

CONCLUSIONS

Distinct metabolomic signatures were observed in AHU and gout. The selected metabolites may have the potential to improve the early detection of gout.

Dataset from dried blood spot acylcarnitine for detection of Carnitine-Acylcarnitine Translocase (CACT) deficiency and Carnitine Palmitoyl Transferase 2 (CPT2) deficiency

Clinical diagnosis of inborn errors of metabolism in the suspected patients is usually guided by the initial general investigations in the laboratory such as the concentration of ammonia, blood gases status, blood glucose and ketones. The establishment of a biochemical diagnosis in patients with inborn errors of metabolism depends on the detection of the specific metabolites in the abnormal metabolic pathway which can appear in any of the body fluids but are most commonly tested in blood and urine samples. Acylcarnitine and/or acylcarnitine ratio in patients with carnitine acylcarnitine translocase and carnitine palmitoyl transferase deficiency showed an abnormal profile regardless of the metabolic status of patients. The acylcarnitine was derived from the analysis of dried blood spot using multiple reaction monitoring (MRM) which was performed using quadrupole mass spectrometry. The dataset presented in this article was generated from analysis of acylcarnitines in the 17,121 dried blood spots from symptomatic Malaysian patients less than fifty years old who exhibited symptoms suggestive of inborn errors of metabolism, but had a normal acylcarnitine profile. A precursor or ion scan of m/z 85 was selected for the analysis. Quantification of each analyte was obtained using the signal intensity ratio of the acylcarnitine to its internal standard. The acylcarnitines analyzed included C0, C2, C3, C3DC, C4, C5, C5:1, C5DC, C5OH, C6, C8, C10, C12, C14, C16, C18, C18:1, C16OH, C18OH and C18:1OH and was analyzed using Neolynx V4.0 software. We decided to choose the 1st and 99th percentiles as the minimum and maximum cut-offs. The filtered part of data in this article was used in the article Novel mutations associated with Carnitine-Acylcarnitine Translocase and Carnitine Palmitoyl Transferase 2 deficiencies in Malaysia. This dataset is intended to enable the scientific communities to get access to the raw dataset for future translational research use in inborn errors of metabolism as very few acylcarnitine data was developed and published for the symptomatic patients suspected of inborn errors of metabolism especially in the Asian population.

Do renal and cardiac malformations in the fetus signal carnitine palmitoyltransferase II deficiency? A rare lethal fatty acid oxidation defect

The neonatal form of carnitine palmitoyltransferase II (CPT II) deficiency is a rare lethal inherited disorder of fatty acid oxidation. Carnitine essentially transfers long-chain fatty acids across the mitochondrial membranes for β-oxidation, where CPT II plays a key role. CPT II deficiency phenotypical forms include lethal neonatal, severe infantile and myopathic forms. We present a term small-for-gestational-age neonate with hypoglycaemia, seizures, refractory cardiac arrhythmias and intracranial haemorrhage. Plasma acylcarnitine profile and the genetic study confirmed CPT II deficiency. Additionally, likely pathogenic variants in the SLC22A5 gene point to primary carnitine deficiency. Antenatal findings of polycystic kidney disease and cardiomegaly were confirmed postnatally. All supportive measures, including extracorporeal life support, failed to improve the clinical course, and the baby succumbed. Major renal, cerebral and cardiac anomalies were reported with CPT II deficiency. In our case, fetal polycystic nephromegaly and cardiomegaly with parental consanguinity should have signalled the possibility of this disorder.

One potential hotspot SLC25A20 gene variants in Chinese patients with carnitine-acylcarnitine translocase deficiency

BACKGROUND

Carnitine-acylcarnitine translocase deficiency (CACT deficiency) is a rare and life-threatening autosomal recessive disorder of mitochondrial fatty acid oxidation caused by variant of SLC25A20 gene. The most prevalent missense variant in the SLC25A20 gene in Asia was c.199-10T > G. Due to the c.199-10T > G variant, CACT deficiency is a severe phenotype.

MATERIALS AND METHODS

Herein, we present a neonatal case with c.199-10T > G variant in China and analyze the clinical, biochemical, and genetic aspects of 78 patients previously identified with CACT deficiency.

RESULTS

The patient presented with a series of severe metabolic crises that rapidly deteriorated and eventually died 3 days after delivery. The sequencing of the patient's genome indicated that he was homozygous for the c.199-10T > G variant. 30 patients were found to have the c.199-10T > G mutation, of which 23 were Chinese and 22 were afflicted by the c.199-10T > G splicing variation. In China, c.199-10T > G allele frequency was 82.6%.

CONCLUSION

In CACT deficiency, prompt recognition and treatment are critical. Our data suggested that c.199-10T > G may be a potential hotspot SLC25A20 gene mutation in the Chinese population. Detection of single nucleotide polymorphism is possible for high-risk patients and parents in China.