PHÂN TÍCH GEN SLC25A20 VÀ CPT2 TRONG CHẨN ĐOÁN KHIẾM KHUYẾT BETA OXI HOÁ CỦA AXÍT BÉO Ở TI THỂ

Bệnh lí thiếu hụt Carnitine/acylcarnitine transferase (CACT) và bệnh lí thiếu hụt Carnitine palmitoyltransferase II (CPT II) thuộc nhóm bệnh oxi hóa axit béo trong ti thể. CACT và CPT II là các bệnh lí rối loạn chuyển hóa bẩm sinh (RLCHBS) di truyền hiếm gặp – biến thể di truyền lặn nhiễm sắc thể thường do gen SLC25A20 (gen CACT) và gen CPT2 quy định. Đây là các bệnh lí nguy hiểm để lại các di chứng nặng nề và có thể tử vong. Tuy nhiên, CACT và CPT II có các đặc điểm lâm sàng và cận lâm sàng khá giống với các bệnh lí RLCH oxi hóa axit béo khác và không thể phân biệt về đặc điểm cận lâm sàng và lâm sàng giữa hai bệnh lí này do vậy cần có các phương pháp phù hợp, nhanh chóng để xác định biến thể trên gen SLC25A20 và CPT2 nhằm chẩn đoán và điều trị bệnh. Mục tiêu: Xác định 16 biến thể gen SLC25A20 và 35 biến thể gen CPT2; mô tả kiểu hình và kiểu gen của bệnh nhân mắc biến thể gen SLC25A20/CPT2. Phương pháp: Nghiên cứu ca bệnh gồm mô tả triệu chứng lâm sàng, xét nghiệm sinh hóa và phân tích gen dựa trên phương pháp xây dựng được. Kết quả: Bé gái 10 ngày tuổi, xuất hiện tím tái, ngừng tim, ngưng thở và tử vong. Kết quả xét nghiệm sinh hóa và xét nghiệm amio acid cho thấy hạ glucose máu, nhiễm toan chuyển hóa, tăng amoniac máu; tăng C4, C10, C12, C14, C14OH, C16, C16:1, C16:1OH, C18 và C18:1. Bệnh nhân được xác định có biến thể rs541208710, c.199-10T>G dạng đồng hợp tử trên gen SLC25A20 và 2 biến thể lành tính/ có thể lành tính với bệnh CPT II là rs2229291 (F352C) (c.1055T>G (p.Phe352Cys)) và rs1799821 (V368I) (c.1102G>A (p.Val368Ile)) do vậy chẩn đoán bệnh di truyền mắc phải là bệnh CACT. Kết luận: Xác định 16 biến thể gen SLC25A20 và 35 biến thể gen CPT2 cho phép chẩn đoán xác định bệnh lí RLCHBS di truyền CACT và CPT II.

Carnitine Palmitoyltransferase 1 Regulates Prostate Cancer Growth under Hypoxia

Hypoxia and hypoxia-related biomarkers are the major determinants of prostate cancer (PCa) aggressiveness. Therefore, a better understanding of molecular players involved in PCa cell survival under hypoxia could offer novel therapeutic targets. We previously reported a central role of mitochondrial protein carnitine palmitoyltransferase (CPT1A) in PCa progression, but its role in regulating PCa survival under hypoxia remains unknown. Here, we employed PCa cells (22Rv1 and MDA-PCa-2b) with knockdown or overexpression of CPT1A and assessed their survival under hypoxia, both in cell culture and in vivo models. The results showed that CPT1A knockdown in PCa cells significantly reduced their viability, clonogenicity, and sphere formation under hypoxia, while its overexpression increased their proliferation, clonogenicity, and sphere formation. In nude mice, 22Rv1 xenografts with CPT1A knockdown grew significantly slower compared to vector control cells (~59% reduction in tumor volume at day 29). On the contrary, CPT1A-overexpressing 22Rv1 xenografts showed higher tumor growth compared to vector control cells (~58% higher tumor volume at day 40). Pathological analyses revealed lesser necrotic areas in CPT1A knockdown tumors and higher necrotic areas in CPT1A overexpressing tumors. Immunofluorescence analysis of tumors showed that CPT1A knockdown strongly compromised the hypoxic areas (pimonidazole+), while CPT1A overexpression resulted in more hypoxia areas with strong expression of proliferation biomarkers (Ki67 and cyclin D1). Finally, IHC analysis of tumors revealed a significant decrease in VEGF or VEGF-D expression but without significant changes in biomarkers associated with microvessel density. These results suggest that CPT1A regulates PCa survival in hypoxic conditions and might contribute to their aggressiveness.

Three Novel and One Potential Hotspot CPT1A Variants in Chinese Patients With Carnitine Palmitoyltransferase 1A Deficiency

Carnitine palmitoyltransferase 1A (CPT1A) deficiency is an inherited disorder of mitochondrial fatty acid β-oxidation that impairs fasting ketogenesis and gluconeogenesis in the liver. Few studies implementing newborn screening (NBS) for CPT1A deficiency in the Chinese population have been reported. This study aimed to determine the biochemical, clinical, and genetic characteristics of patients with CPT1A deficiency in China. A total of 204,777 newborns were screened using tandem mass spectrometry at Quanzhou Maternity and Children's Hospital between January 2017 and December 2018. Newborns with elevated C0 levels were recruited, and suspected patients were subjected to further genetic analysis. Additionally, all Chinese patients genetically diagnosed with CPT1A deficiency were reviewed and included in the study. Among the 204,777 screened newborns, two patients were diagnosed with CPT1A deficiency; thus, the estimated incidence in the selected population was 1:102,388. In addition to the two patients newly diagnosed with CPT1A deficiency, we included in our cohort 10 Chinese patients who were previously diagnosed. Five of these 12 patients were diagnosed via NBS. All patients exhibited elevated C0 and/or C0/(C16+C18) ratios. No clinical symptoms were observed in the five patients diagnosed via NBS, while all seven patients presented with clinical symptoms, including fever, cough, vomiting, diarrhea, and seizures. Eighteen distinct CPT1A variants were identified, 15 of which have been previously reported. The three novel variants were c.272T>C (p.L91P), c.734G>A (p.R245Q), and c.1336G>A (p.G446S). in silico analysis suggested that all three novel variants were potentially pathogenic. The most common variant was c.2201T>C (p.F734S), with an allelic frequency of 16.67% (4/24). Our findings demonstrated that NBS for CPT1A deficiency is beneficial. The three novel variants expand the mutational spectrum of CPT1A in the Chinese population, and c.2201T>C (p.F734S) may be a potential hotspot CPT1A mutation.

Carnitine Palmitoyltransferase System: A New Target for Anti-Inflammatory and Anticancer Therapy?

Lipid metabolism involves multiple biological processes. As one of the most important lipid metabolic pathways, fatty acid oxidation (FAO) and its key rate-limiting enzyme, the carnitine palmitoyltransferase (CPT) system, regulate host immune responses and thus are of great clinical significance. The effect of the CPT system on different tissues or organs is complex: the deficiency or over-activation of CPT disrupts the immune homeostasis by causing energy metabolism disorder and inflammatory oxidative damage and therefore contributes to the development of various acute and chronic inflammatory disorders and cancer. Accordingly, agonists or antagonists targeting the CPT system may become novel approaches for the treatment of diseases. In this review, we first briefly describe the structure, distribution, and physiological action of the CPT system. We then summarize the pathophysiological role of the CPT system in chronic obstructive pulmonary disease, bronchial asthma, acute lung injury, chronic granulomatous disease, nonalcoholic fatty liver disease, hepatic ischemia–reperfusion injury, kidney fibrosis, acute kidney injury, cardiovascular disorders, and cancer. We are also concerned with the current knowledge in either preclinical or clinical studies of various CPT activators/inhibitors for the management of diseases. These compounds range from traditional Chinese medicines to novel nanodevices. Although great efforts have been made in studying the different kinds of CPT agonists/antagonists, only a few pharmaceuticals have been applied for clinical uses. Nevertheless, research on CPT activation or inhibition highlights the pharmacological modulation of CPT-dependent FAO, especially on different CPT isoforms, as a promising anti-inflammatory/antitumor therapeutic strategy for numerous disorders.

Detection of Early Onset Carnitine Palmitoyltransferase II Deficiency by Newborn Screening. Should CPT II Deficiency Be a Primary Disease Target?

Early-onset carnitine palmitoyltransferase II deficiency (CPT II deficiency) (OMIM 600650) can result in severe outcomes, which are often fatal in the neonatal to infantile period. CPT II deficiency is a primary target in the Maritime Newborn Screening Program. We report a case of neonatal-onset CPT II deficiency identified through expanded newborn screening with tandem mass spectrometry. Identification through newborn screening led to early treatment interventions, avoidance of metabolic decompensation, and a better clinical outcome. Newborn screening for CPT II deficiency is highly sensitive and specific with no false positives identified. The only screen positive case detected identified a true positive case. This experience illustrates the importance of newborn screening for CPT II deficiency and demonstrates why reconsideration should be taken to add this disease as a primary newborn screening target.

Novel mutation in carnitine palmitoyltransferase 1A detected through newborn screening for a presymptomatic case in China: a case report

Background Carnitine palmitoyltransferase 1A (CPT1A) deficiency is a rare mitochondrial fatty acid oxidation (FAO) disorder that results in hypoketotic hypoglycemia and hepatic encephalopathy. It is caused by mutation in CPT1A. To date, only two symptomatic cases of CPT1A deficiency have been reported in China. Case presentation A newborn male, without any disease-related clinical manifestations, was diagnosed with CPT1A deficiency through newborn screening. Increased free carnitine levels and a significantly increased C0/(C16 + C18) ratio were detected by tandem mass spectrometry, and subsequently, mutations in CPT1A were found by gene sequence analysis. The patient was advised a low-fat, high-protein diet and followed up regularly. During three-years of follow-up since, the patient showed normal growth velocity and developmental milestones. Whole-exome sequence identified two mutations, c.2201 T > C (p.F734S) and c.1318G > A (p.A440T), in the patient. The c.2201 T > C mutation, which has been reported previously, was inherited from his father, while the c.1318G > A, a novel mutation, was inherited from his mother. The amino acid residues encoded by original sequences are highly conserved across different species. These mutations slightly altered the three-dimensional structure of the protein, as analyzed by molecular modeling, suggesting that they may be pathogenic. Conclusion This is the first case of CPT1A deficiency detected through newborn screening based on diagnostic levels of free carnitine, in China. Three years follow-up suggested that early diagnosis and diet management may improve the prognosis in CPT1A patient. In addition, we identified a novel mutation c.1318G > A in CPT1A,and a possible unique to Chinese lineage mutation c.2201 T > C. Our findings have expanded the gene spectrum of this rare condition and provided a basis for family genetic counseling and prenatal diagnosis.