BACKGROUND: Severe combined immunodeficiency (SCID) is the most fatal form of inherited primary immunodeficiency disease. Known molecular defect mutations occur in most children with SCID.
METHODS: Herein, we report Adenosine Deaminase-SCID (ADA-SCID) using whole-exome sequencing (WES), explore exome mutational landscape and significance for 17 SCID samples, and verify the mutated exon genes using the Gene Expression Omnibus (GEO) datasets. A total of 250 patients, who were hospitalized at the Neonatal Intensive Care Unit (NICU) of The Seventh Medical Center of the PLA General Hospital for 3 years (from 2017 to 2020), were screened for SCID. We collected mutated genes from the WES data of 17 SCID children. GSE609 and GSE99176 cohorts were used to identify the expressions of mutated exon genes and molecular features in SCID. Gene set variation analyses (GSVA) and correlation analyses were performed.
RESULTS: The detection rate with approximately 6.8 % (17/250) of SCID is high in the NICU. A total of 16 genes were identified among 17 SCID samples, of which the Top 2 genes (MUC6 and RP11-683L23.1) might be crucial in the progression of SCID with 94 % mutation frequency. Furthermore, CNN2 and SCGB1C1 had significant co-mutations and may cooperate to affect SCID development. Importantly, the phylogenetic tree classification results of 17 SCID samples are more correlated to MUC6 with the most significant mutations. Expression profiles of seven mutated genes and five mutated genes were documented in GSE609 and GSE99176 cohorts based on microarray, respectively. Several immune-related pathways were significantly enriched, and Foxd4, differing from the other four mutated genes, was inversely correlated with the GSVA-enriched pathway.
CONCLUSIONS: Due to its high detection rate (6.8%) and fatality rate (100%), the inclusion of SCID in newborn screening (NBS) is urgent for children in China. The WES successfully identified several common exonic variants (e.g., MUC6) and depicted the feature of mutations and evolution, which will help develop new diagnostic methods for SCID.

Hepatocellular carcinoma (HCC) is the leading malignancy associated with cancer-related deaths worldwide. Many studies have indicated that mucin (MUC) expression plays an important role in cancer metastasis and recurrence. MUC6 expression is observed in gastric and oncocytic phenotypes and may play an important role during cancer progression. We found the level of MUC6 is lower in HCC patients but did not affect the survival of HCC patients. Therefore, in this study, we investigated the combined effect of MUC6 polymorphisms and exposure to environmental carcinogens on the susceptibility to and clinicopathological characteristics of HCC. Three single-nucleotide polymorphisms (SNPs) of MUC6 (rs61869016, rs6597947, and rs7481521) from 1197 healthy controls and 423 HCC patients were analyzed using real-time PCR. After adjusting for other co-variants, we found that carrying a CC genotype at MUC6 rs61869016 had a lower risk of developing HCC than wildtype carriers. Moreover, patients with a smoking habit who carried the C allele of rs61869016 and T allele of rs7481521 had a higher (B or C) Child-Pugh score than other genotypes, suggesting significant functional compromise and decompensated disease. Therefore, our findings suggest that genetic variations in MUC6 may corelate to HCC and indicate progression in HCC patients.

Wilms tumor is the most common renal malignancy in children. Known gene mutations account for about 40% of all wilms tumor cases, but the full map of genetic mutations in wilms tumor is far from clear. Whole genome sequencing and RNA sequencing were performed in 5 pairs of wilms tumor tissues and adjacent normal tissues to figure out important genetic mutations. Gene knock-down, CRISPR-induced mutations were used to investigate their potential effects in cell lines and in-vivo xenografted model. Mutations in seven novel genes (MUC6, GOLGA6L2, GPRIN2, MDN1, MUC4, OR4L1 and PDE4DIP) occurred in more than one patient. The most prevalent mutation was found in MUC6, which had 7 somatic exonic variants in 4 patients. In addition, TaqMan assay and immunoblot confirmed that MUC6 expression was reduced in WT tissues when compared with control tissues. Moreover, the results of MUC6 knock-down assay and CRISPR-induced MUC6 mutations showed that MUC6 inhibited tumor aggression via autophagy-dependent β-catenin degradation while its mutations attenuated tumor-suppressive effects of MUC6. Seven novel mutated genes (MUC6, GOLGA6L2, GPRIN2, MDN1, MUC4, OR4L1 and PDE4DIP) were found in WT, among which MUC6 was the most prevalent one. MUC6 acted as a tumor suppressive gene through autophagy dependent β-catenin pathway.

OBJECTIVE: This study aimed to investigate the mechanistic downregulation of mucin 6 (MUC6) and its influence on the progression of gastric cancer (GC).
METHODS: The expression of MUC6 was examined in 40 GC patients. The methylation status of the MUC6 promoter region was investigated using GC cell lines and GC tissue specimens by immunohistochemistry and/or quantitative polymerase chain reaction (qPCR). MUC6 was knocked down in the gastric epithelial cells (GES-1) cell and overexpressed in the SGC7901 cell. The effects of MUC6 knockdown and overexpression on cell migration and invasion were examined using Transwell assays. The effects of demethylation and methylation on MUC6 expression were examined by western blot, qPCR, or double luciferase reporter assays.
RESULTS: The expression of MUC6 in GC with lymph node metastasis and poor pathological stage was significantly lower than that in GC without lymph node metastasis and good pathological stage, respectively. While cell migration and invasion were significantly decreased after overexpression of MUC6, these abilities significantly increased after the knockdown of MUC6. The methylation levels of MUC6 in GC tissues and GC cell lines were significantly higher than those in para-cancerous tissues and normal GES. Promoter methylation could significantly reduce the binding of related transcription factors to the MUC6 promoter. The expression of MUC6 increased with the concentration and time of action of demethylation drugs.
CONCLUSIONS: Expression of MUC6 was regulated by promotor methylation. This methylation of the MUC6 promoter may lead to significant downregulation of MUC6 in GC and promote the progression of GC.

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease of unknown aetiology. In this study, we aimed to identify the mutations and aberrant expression of mucins associated with ITP pathogenesis.
First, we investigated the DNA mutation profile of bone marrow samples from patients with ITP (n = 20) by using next-generation sequencing (NGS). In addition, MUC3A, MUC5B and MUC6 were mutated in all patients with ITP. ELISA (enzyme-linked immunoassay) was used to measure MUC3A, MUC5B and MUC6 levels in the plasma of bone marrow fluid mononuclear cells (BMMCs) and peripheral blood mononuclear cells (PBMCs). Real-time quantitative PCR was used to study the mRNA expression levels of MUC3A, MUC5B and MUC6 in BMMCs and PBMCs.
The results indicated that there were 3998 missense mutations involving 2269 genes in more than 10 individuals. MUC3A levels were not significantly different among the three groups, whereas MUC5B and MUC6 expression were significantly down-regulated in patients with ITP compared with healthy controls. In addition, serum MUC5B and MUC6 levels were significantly higher in patients with ITP in clinical remission than in patients with active ITP.
Taken together, these results suggest that genetic alterations and the aberrant serum expression of mucins might be involved in the pathogenesis of ITP.