Solution structures and effects of a platinum compound successively bound MYC G-quadruplex.

G-quadruplex (G4) structures play integral roles in modulating biological functions and can be regulated by small molecules. The MYC gene is critical during tumor initiation and malignant progression, in which G4 acts as an important modulation motif. Herein, we reported the MYC promoter G4 recognized by a platinum(II) compound Pt-phen. Two Pt-phen-MYC G4 complex structures in 5 mM K+ were determined by NMR. The Pt-phen first strongly binds the 3'-end of MYC G4 to form a 1:1 3'-end binding complex and then binds 5'-end to form a 2:1 complex with more Pt-phen. In the complexes, the Pt-phen molecules are well-defined and stack over four bases at the G-tetrad for a highly extensive π-π interaction, with the Pt atom aligning with the center of the G-tetrad. The flanking residues were observed to rearrange and cover on top of Pt-phen to stabilize the whole complex. We further demonstrated that Pt-phen targets G4 DNA in living cells and represses MYC gene expression in cancer cells. Our work elucidated the structural basis of ligand binding to MYC promoter G4. The platinum compound bound G4 includes multiple complexes formation, providing insights into the design of metal ligands targeting oncogene G4 DNA.

Pseudoexon activation by deep intronic variation in GNE myopathy with thrombocytopenia.

INTRODUCTION/AIMS: GNE myopathy is a rare autosomal recessive disorder caused by pathogenic variants in the GNE gene, which is essential for the sialic acid biosynthesis pathway. Although over 300 GNE variants have been reported, some patients remain undiagnosed with monoallelic pathogenic variants. This study aims to analyze the entire GNE genomic region to identify novel pathogenic variants. METHODS: Patients with clinically compatible GNE myopathy and monoallelic pathogenic variants in the GNE gene were enrolled. The other GNE pathogenic variant was verified using comprehensive methods including exon 2 quantitative polymerase chain reaction and nanopore long-read single-molecule sequencing (LRS). RESULTS: A deep intronic GNE variant, c.862+870C>T, was identified in nine patients from eight unrelated families. This variant generates a cryptic splice site, resulting in the activation of a novel pseudoexon between exons 5 and 6. It results in the insertion of an extra 146 nucleotides into the messengerRNA (mRNA), which is predicted to result in a truncated humanGNE1(hGNE1) protein. Peanut agglutinin（PNA） lectin staining of muscle tissues showed reduced sialylation of mucin O-glycans on sarcolemmal glycoproteins. Notably, a third of patients with the c.862+870C>T variant exhibited thrombocytopenia. A common core haplotype harboring the deep intronic GNE variant was found in all these patients. DISCUSSION: The transcript with pseudoexon activation potentially affects sialic acid biosynthesis via nonsense-mediated mRNA decay, or resulting in a truncated hGNE1 protein, which interferes with normal enzyme function. LRS is expected to be more frequently incorporated in genetic analysis given its efficacy in detecting hard-to-find pathogenic variants.

Diagnosis of Challenging Spinal Muscular Atrophy Cases with Long-Read Sequencing.

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder primarily caused by the deletion or mutation of the survival motor neuron 1 (SMN1) gene. This study assesses the diagnostic potential of long-read sequencing (LRS) in three patients with SMA. For Patient 1, who has a heterozygous SMN1 deletion, LRS unveiled a missense mutation in SMN1 exon 5. In Patient 2, an Alu/Alu-mediated rearrangement covering the SMN1 promoter and exon 1 was identified through a blend of multiplex ligation-dependent probe amplification, LRS, and PCR across the breakpoint. The third patient, born to a consanguineous family, bore four copies of hybrid SMN genes. LRS determined the genomic structures, indicating two distinct hybrids of SMN2 exon 7 and SMN1 exon 8. However, a discrepancy was found between the SMN1/SMN2 ratio interpretations by LRS (0:2) and multiplex ligation-dependent probe amplification (0:4), which suggested a limitation of LRS in SMA diagnosis. In conclusion, this newly adapted long PCR-based third-generation sequencing introduces an additional avenue for SMA diagnosis.

Diagnostic delay in late-onset Pompe disease among Chinese patients: A retrospective study.

Surveys and retrospective studies have revealed considerable delays in diagnosing late-onset Pompe disease (LOPD) in China, where the contributing factors remain poorly represented. Our study analyzed the diagnostic journey of 34 LOPD patients seen at our neuromuscular clinic from 2005 to 2022. We defined diagnostic delay as the time from the onset of the first relevant symptoms and laboratory findings suggestive of LOPD to the eventual diagnosis, and we constructed a correlation matrix to assess relationships among these variables. The cohort consisted of 34 patients with an equal male-to-female ratio, and the mean age at diagnosis was 27.68 ± 10.03 years. We found the median diagnostic delay to be 5 years, with a range of 0.3 to 20 years, with 97.1% having been misdiagnosed previously, most commonly with "Type II Respiratory insufficiency" (36.7%). Notably, patients at earlier onset (mean age, 18.19 years vs. 31 years; p < 0.005) tended to have higher creatine kinase (CK) levels. Furthermore, 92.6% reported difficulty in sitting up from a supine position since childhood. Our research emphasizes the role of early indicators like dyspnea and difficulty performing sit-ups in adolescents for timely LOPD diagnosis and treatment initiation. The importance of early high-risk screening using dried blood spot testing cannot be overstated.