The state of California (CA) added X-linked adrenoleukodystrophy (X-ALD) to newborn screening (NBS) in 2016 via the measurement of C26:0-lysophosphatidylcholine (C26:0-LPC) in a two-tier fashion, followed by sequencing of the ABCD1 gene. This has resulted in the identification of individuals with genetic conditions beyond X-ALD that can also result in elevated C26:0-LPC by NBS. We describe the biochemical, molecular, and clinical characteristics of nine patients from two metabolic centers in California who screened positive by NBS for elevated C26:0-LPC between 2016 and 2022 and were ultimately diagnosed with a genetic condition other than X-ALD. Seven individuals were diagnosed with Zellweger spectrum disorder (ZSD) due to biallelic variants in PEX genes. One male was diagnosed with Klinefelter syndrome and one female was found to have an X chromosome contiguous gene deletion syndrome after the identification of a heterozygous VUS and hemizygous VUS variant in ABCD1, respectively. Patients with ZSD had significantly higher first- and second-tier C26:0-LPC levels compared to the two non-ZSD cases. Identification of children with ZSD and atypical patterns of ABCD1 variants is a secondary benefit of NBS for X-ALD, leading to earlier diagnosis, prompt therapeutic initiation, and more accurate genetic counseling. As screening for X-ALD continues via the measurement of C26:0-LPC, our knowledge of additional genetic conditions associated with elevated C26:0-LPC will continue to advance, allowing for increased recognition of other genetic disorders for which early intervention is warranted.

BACKGROUND: Zellweger Syndrome (ZS), or cerebrohepatorenal syndrome, is a rare disorder due to PEX gene mutations affecting peroxisome function. While PEX6 coding mutations are known to cause ZS, the impact of noncoding mutations is less clear.
METHODS: A Chinese neonate and his family were subjected to whole exome sequencing (WES) and bioinformatics to assess variant pathogenicity. A minigene assay was also performed for detailed splicing variant analysis.
RESULTS: WES identified compound heterozygous PEX6 variants: c.315G>A (p. Trp105Ter) and c.2095-3 T>G. Minigene assays indicated that the latter variant led to abnormal mRNA splicing and the loss of exon 11 in PEX6 expression, potentially causing nonsense-mediated mRNA decay (NMD) or truncated protein structure.
CONCLUSIONS: The study suggests that PEX6: c.2095-3 T>G might be a genetic contributor to the patient\'s condition, broadening the known mutation spectrum of PEX6. These insights lay groundwork for potential gene therapy for such variants.

暂无摘要。

患儿　男，11月龄，因“抬头不稳、反应差8个月”入院，表现为抬头不稳、反应能力差、发育停滞、抽搐发作，患儿肝功能异常，父母为近亲婚配，基因检查示c.493G>C纯合变异，分别来源于表型正常父亲和母亲，临床确诊“Zellweger综合征”，予护肝、抗癫痫等治疗，好转出院。.

Zellweger Syndrome is a peroxisomal disorder that can lead to elevation of long chain fatty acids and epilepsy, which can be drug resistant. The treatment of drug resistant epilepsy can include the ketogenic diet in appropriately chosen patients. Typically, the ketogenic diet is contraindicated in individuals with defects in fatty acid metabolism because of the diet\'s reliance on medium and long chain fatty acids. To our knowledge this is the first publication outlining the use of the ketogenic diet in patients with defects in beta oxidation of very long chain fatty acids. We present two patients with Zellweger Syndrome who were placed on a ketogenic diet for drug resistant epilepsy. Safety and tolerance of the ketogenic diet in patients with Zellweger Syndrome.

Zellweger syndrome is an autosomal recessive disease within the spectrum of peroxisome biogenesis disorder manifesting in the neonatal period with profound dysfunction of the central nervous system, liver and kidney. Common clinical presentations include hypotonia, seizure, hepatomegaly, craniofacial dysmorphism and early death. Mutation in one of the PEX genes coding for a peroxisome assembly protein creates a functionally incompetent organelle causing accumulation of very long chain fatty acids in various organs. Here we report the case of a 5-month-old male presented at birth with hypotonia, poor feeding, gross congenital anomalies and later during early infancy with failure to thrive, several episodes of seizures, aspiration due to feeding difficulties and recurrent severe pneumonia. A whole genomic sequencing brought us to the final diagnosis of Zellweger syndrome. Despite an absence of treatment options, prompt diagnosis of Zellweger syndrome is important for providing appropriate symptomatic care, definitive genetic testing and prenatal counselling.
UNASSIGNED: case reports; mutation; neonate; Zellweger syndrome.

Peroxisome biogenesis disorders (PBDs) represent a group of metabolic conditions that cause severe developmental defects. Peroxisomes are essential metabolic organelles, present in virtually every eukaryotic cell and mediating key processes in immunometabolism. To date, the full spectrum of PBDs remains to be identified, and the impact PBDs have on immune function is unexplored. This study presents a characterization of the hepatic immune compartment of a neonatal PBD mouse model at single-cell resolution to establish the importance and function of peroxisomes in developmental hematopoiesis. We report that hematopoietic defects are a feature in a severe PBD murine model. Finally, we identify a role for peroxisomes in the regulation of the major histocompatibility class II expression and antigen presentation to CD4+ T cells in dendritic cells. This study adds to our understanding of the mechanisms of PBDs and expands our knowledge of the role of peroxisomes in immunometabolism.

The gold-standard diagnostic test for peroxisomal disorders (PDs) is plasma concentration analysis of very long-chain fatty acids (VLCFAs). However, this method\'s time-consuming nature and limitations in cases which present normal VLCFA levels necessitates alternative approaches. The analysis of C26:0-lysophosphatydylcholine (C26:0-LPC) in dried blood spot samples by tandem-mass spectrometry (MS/MS) has successfully been implemented in certain newborn screening programs to diagnose X-linked adrenoleukodystrophy (ALD). However, the diagnostic potential of very long-chain LPCs concentrations in plasma remains poorly understood. This study sought to evaluate the diagnostic performance of C26:0-LPC and other very long-chain LPCs, comparing them to VLCFA analysis in plasma. The study, which included 330 individuals affected by a peroxisomal β-oxidation deficiency and 407 control individuals, revealed that C26:0- and C24:0-LPC concentrations demonstrated the highest diagnostic accuracy (98.8% and 98.4%, respectively), outperforming VLCFA when C26:0/C22:0 and C24:0/C22:0 ratios were combined (98.1%). Combining C24:0- and C26:0-LPC gave the highest sensitivity (99.7%), with ALD females exhibiting notably higher sensitivity compared with the VLCFA ratio combination (98.7% vs. 93.5%, respectively). In contrast, C22:0-LPC exhibited suboptimal performance, primarily due to its low sensitivity (75%), but we identified a potential use to help distinguish between ALD and Zellweger spectrum disorders. In summary, MS/MS analysis of plasma C24:0- and C26:0-LPC concentrations represents a rapid and straightforward approach to diagnose PDs, demonstrating superior diagnostic accuracy, particularly in ALD females, compared with conventional VLCFA biomarkers. We strongly recommend integrating very-long chain LPC plasma analysis in the diagnostic evaluation of individuals suspected of having a PD.

Renal cystic diseases (RCDs) can arise from utero to early adulthood and present with a variety of symptoms including renal, hepatic, and cardiovascular manifestations. It is well known that common RCDs such as autosomal polycystic kidney disease and autosomal recessive kidney disease are linked to genes such as PKD1 and PKHD1, respectively. However, it is important to investigate the genetic pathophysiology of how these gene mutations lead to clinical symptoms and include some of the less-studied RCDs, such as autosomal dominant tubulointerstitial kidney disease, multicystic dysplastic kidney, Zellweger syndrome, calyceal diverticula, and more. We plan to take a thorough look into the genetic involvement and clinical sequalae of a number of RCDs with the goal of helping to guide diagnosis, counseling, and treatment.

Objective: To summarize the clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation. Methods: This was a case series research. Clinical date and genetic results of 2 neonatal cases of Zellweger syndrome caused by PEX6 gene variation in Wuhan Children\'s Hospital, Tongji Medical College, Huazhong University of Science & Technology and Affiliated Hospital of Guangdong Medical University from July 2021 to July 2022 were retrospectively collected and analyzed. Literature up to August 2023 was searched from electronic databases of China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed with the combined keywords of \"Zellweger syndrome\" \"Zellweger spectrum disorder\", and \"PEX6 gene\" both in Chinese and English. The main clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation were summarized. Results: The 2 male neonates both developed clinical manifestations as dyspnea, hypotonia, feeding difficulties, enlarged fontanelle, and high palatine arch after birth. Biochemical parameters indicated elevated bile acids, and the cranial ultrasound showed the enlarged bilateral ventricles and subependymal cyst in both 2 neonates. Zellweger syndrome was confirmed by whole exome sequencing, and the results revealed PEX6 gene variation in the 2 neonates, including compound heterozygous variants c.315G>A and c.2095-3T>G, and homozygous variant c.506_507del. Case 1 was hospitalized for 5 days, and case 2 for 32 days; they both died shortly after being discharged (the specific time is unknown). Literature review found 26 patients, including 2 neonates in this study, with Zellweger spectrum disorder caused by PEX6 gene defect reported in 1 Chinese article and 11 English articles. Clinical features included hearing loss (19 cases), developmental delay (19 cases), vision impairment (19 cases), elevated very long chain fatty acids (17 cases), brain malformations (15 cases), hypotonia (12 cases), hepatic insufficiency (12 cases), distinctive facies (10 cases), and dental impairment (9 cases). Compound heterozygous variations dominated the variation types (15 cases), and the frameshift variations (16 cases) were the main pathogenic variations. Conclusions: Zellweger spectrum disorder should be considered when neonates show hypotonia, feeding difficulty, distinctive facial appearance, brain malformations and failure of hearing screening, or when older children show retinitis pigmentosa, sensorineural hearing loss, amelogenesis imperfecta and developmental delays. Detection of genetic variation in the PEX gene is crucial for definitive diagnosis.
目的： 总结PEX6基因变异致Zellweger谱系障碍患儿的临床表型和遗传学特点。 方法： 病例系列研究，回顾性分析2021年7月至2022年7月华中科技大学同济医学院附属武汉儿童医院和广东医科大学附属医院诊治的2例因PEX6基因变异致Zellweger综合征新生儿的临床资料和遗传学检测结果。并分别以“Zellweger综合征”“Zellweger谱系障碍”“PEX6基因”或“Zellweger syndrome”“Zellweger spectrum disorder”“PEX6 gene”为关键词检索中国知网、万方数据库和PubMed数据库自建库至2023年8月的中英文文献。对PEX6基因变异致Zellweger谱系障碍患儿的主要临床表现和基因型特点进行描述和总结。 结果： 2例患儿均为男性，均为新生儿，均出生后出现呼吸困难、肌张力低下、喂养困难、前囟增大、高腭弓等临床表现，实验室结果均提示胆汁酸升高，颅脑彩色超声检查均提示双侧脑室增宽、室管膜下囊肿。全外显子测序分析发现2例患儿均为PEX6基因变异，分别为复合杂合变异（c.315G>A和c.2095-3T>G）、纯合变异（c.506_507del），均诊断为PEX6基因变异致Zellweger综合征。2例患儿分别于住院第5天和第32天因家长要求出院，出院后不久（具体时间不详）均死亡。文献复习符合检索条件中文文献1篇、英文文献11篇，包括本研究2例共26例患儿。主要临床表现为听力损伤（19例）、发育迟滞（19例）、视力异常（19例）、极长链脂肪酸升高（17例）、颅脑结构畸形（15例）、肌张力低下（12例）、肝脏异常（12例）、特殊面容（10例）、牙齿损伤（9例）。变异类型中以复合杂合变异（15例）为主，致病性变异以错义变异为主（16例）。 结论： 当新生儿存在肌张力低下、喂养困难、特殊面容、颅脑结构畸形以及听力筛查未通过或年长儿存在视网膜色素变性、感音性耳聋、牙釉质损伤、发育迟滞时，需考虑Zellweger谱系障碍。基因检测发现PEX基因变异可明确诊断。.