Variable phenotype of a null PPP1R13L allele in children with dilated cardiomyopathy

Childhood-onset cardiomyopathy is a genetically heterogeneous group of conditions with several genes implicated. Recently, biallelic loss-of-function variants in PPP1R13L have been reported in association with a syndromic form of dilated cardiomyopathy (DCM). In addition, affected children manifest skin and hair abnormalities, cleft lip and palate (CLP), and eye findings. Here, we delineate the condition further by describing the phenotype associated with a homozygous frameshift variant (p.Arg330 ProfsTer76) in PPP1R13L detected in two sibships in a consanguineous family with six affected children. The index case had DCM and wooly hair, two of his siblings had DCM and CLP while three cousins had, in addition, glaucoma. Global developmental delay was observed in one child. All the children, except one, died during early childhood. Whole exome sequencing and whole genome sequencing did not reveal any other plausible variant. We provide further evidence that implicates PPP1R13L in a variable syndromic form of severe childhood-onset DCM and suggests expanding the spectrum of this condition to include glaucoma. Given the variability of the phenotype associated with PPP1R13-related DCM, a thorough evaluation of each case is highly recommended even in the presence of an apparently isolated DCM.

Malignant transformation of human bronchial epithelial cells induced by benzo [a] pyrene suggests a negative feedback of TP53 to PPP1R13L via binding a possible enhancer element

Previous studies have shown that PPP1R13L as an inhibitor of apoptosis protease TP53 can lead to abnormal cell proliferation and carcinogenesis, however, the function of PPP1R13L was complicated and the interaction between TP53 and PPP1R13L needs to be further explored. In the present study, a malignant transformation model of human bronchial epithelial cells induced by benzo (a) pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) was established to observe the regulatory patterns between TP53 and PPP1R13L during carcinogenesis. In vitro experiments including CRISPR-Cas9 editing, RNA silence, Co-Immunoprecipitation and Chromatin Immunoprecipitation were applied to discuss their interactive effects. Additionally, TCGA data profile and our clinical samples of lung cancer were also used to analyze their relationship at the transcriptome level. Interestingly, we found that the mRNA and protein level of TP53 and PPP1R13L fluctuated as a wave in BPDE-induced malignant transformation under wild-type TP53 genetic background. Our results have also demonstrated that PPP1R13L acts as an inhibitor of TP53, while TP53 can regulate PPP1R13L via binding a possible enhancer of the first intron of PPP1R13L gene. Likewise, TCGA data and clinical samples have identified that in the case of TP53 mutation, TP53 expression was negatively correlated with PPP1R13L, while in the case of TP53 wild-type, TP53 expression was not correlated with PPP1R13L. It suggested that there existed a negative feedback of wild-type TP53 to PPP1R13L, which reminded a unique implication during chemical carcinogenesis.

Biallelic variants in PPP1R13L cause paediatric dilated cardiomyopathy

Childhood dilated cardiomyopathy (DCM) is a leading cause of heart failure requiring cardiac transplantation and approximately 5% of cases result in sudden death. Knowledge of the underlying genetic cause can aid prognostication and clinical management and enables accurate recurrence risk counselling for the family. Here we used genomic sequencing to identify the causative genetic variant(s) in families with children affected by severe DCM. In an international collaborative effort facilitated by GeneMatcher, biallelic variants in PPP1R13L were identified in seven children with severe DCM from five unrelated families following exome or genome sequencing and inheritance-based variant filtering. PPP1R13L encodes inhibitor of apoptosis-stimulating protein of p53 protein (iASPP). In addition to roles in apoptosis, iASPP acts as a regulator of desmosomes and has been implicated in inflammatory pathways. DCM presented early (mean: 2 years 10 months; range: 3 months-9 years) and was progressive, resulting in death (n = 3) or transplant (n = 3), with one child currently awaiting transplant. Genomic sequencing technologies are valuable for the identification of novel and emerging candidate genes. Biallelic variants in PPP1R13L were previously reported in a single consanguineous family with paediatric DCM. The identification here of a further five families now provides sufficient evidence to support a robust gene-disease association between PPP1R13L and severe paediatric DCM. The PPP1R13L gene should be included in panel-based genetic testing for paediatric DCM.

GLTSCR1, ATM, PPP1R13L and CD3EAP Genetic Variants and Lung Cancer Risk in a Chinese Population

Genetic variants in glioma tumor suppressor candidate region gene 1 (GLTSCR1) and ATM serine/threonine kinase (ATM) have been associated with various cancer risks. Epidemiological studies also revealed the association of variants of GLTSCR1 and ATM genes with different brain tumors. However, little is known about the relationship between both gene polymorphisms and lung cancer risk. We conducted a Chinese hospital-based casecontrol study involving 384 lung cancer cases and 387 cancer-free controls. No significant differences in the single polymorphism (GLTSCR1 rs1035938 and ATM rs11212592) association were found in five genetic models (co-dominant, dominant, recessive, overdominant and log-additive models) (adjusted by smoking duration). Join effect of three SNPs (PPP1R13L rs1970764, CD3EAP rs967591, GLTSCR1 rs1035938) on chromosome 19q13.3 showed that the designated haplotype8 (rs 1970764^G-rs967591^A-rs1035938^C) [OR (95% CI)=1.60(1.11-2.32), P/0.012] andhaplotype8 (rs1970764^G-rs967591^G-rs1035938^T) [OR (95% CI)=2.45 (1.17-5.12), P=0.018] were associated with increased risk of lung cancer (adjusted by smoking duration). The analysis of multifactor dimensionality reduction revealed that two 3-way models were the best fit models in analyses of 2 loci (P<0.001) or 4 loci (Р=0.015-0.016). The entropy-based analysis indicated the strongest synergistic effect between PPP1R13L rs1970764 and ATM rs11212592 in analysis of four genes. In conclusion, our study suggests that haplotypes consisting of PPP1R13L rs1970764-CD3EAP rs961591-GLTSCR1 rs1035938 on Chr19q13.3, interaction of smoking and GLTSCR1 rs1035938-ATM rs11212592, and synergistic action of PPP1R13L rs1970764 and ATM rs11212592 may associate with lung cancer risk in the Chinese population.

Sequence variation in PPP1R13L results in a novel form of cardio-cutaneous syndrome

Dilated cardiomyopathy (DCM) is a life-threatening disorder whose genetic basis is heterogeneous and mostly unknown. Five Arab Christian infants, aged 4-30 months from four families, were diagnosed with DCM associated with mild skin, teeth, and hair abnormalities. All passed away before age 3. A homozygous sequence variation creating a premature stop codon at PPP1R13L encoding the iASPP protein was identified in three infants and in the mother of the other two. Patients' fibroblasts and PPP1R13L-knocked down human fibroblasts presented higher expression levels of pro-inflammatory cytokine genes in response to lipopolysaccharide, as well as Ppp1r13l-knocked down murine cardiomyocytes and hearts of Ppp1r13l-deficient mice. The hypersensitivity to lipopolysaccharide was NF-κB-dependent, and its inducible binding activity to promoters of pro-inflammatory cytokine genes was elevated in patients' fibroblasts. RNA sequencing of Ppp1r13l-knocked down murine cardiomyocytes and of hearts derived from different stages of DCM development in Ppp1r13l-deficient mice revealed the crucial role of iASPP in dampening cardiac inflammatory response. Our results determined PPP1R13L as the gene underlying a novel autosomal-recessive cardio-cutaneous syndrome in humans and strongly suggest that the fatal DCM during infancy is a consequence of failure to regulate transcriptional pathways necessary for tuning cardiac threshold response to common inflammatory stressors.

Association of PPP1R13L and CD3EAP polymorphisms with risk and survival of non-small cell lung cancer in Chinese non-smoking females

PPP1R13L and CD3EAP were confirmed to play important roles in transcription and apoptosis. SNPs in PPP1R13L and CD3EAP may be associated with lung cancer risk and survival. This study investigated the association of PPP1R13L rs1005165 and CD3EAP rs967591 with non-small cell lung cancer (NSCLC) risk and survival in Chinese non-smoking females. 442 NSCLC cases and 480 cancer-free controls were conducted in the case-control study, and 283 cases were in cohort study. Genotype was determined by Taqman real-time PCR. The statistical analyses were performed by SPSS 22.0 software. We found that rs1005165 and rs967591 were significantly associated with NSCLC risk in Chinese non-smoking females. For rs1005165, compared with homozygous wild CC genotype, carriers of CT or TT genotype had lower risk of NSCLC (adjusted ORs were 0.675 and 0.713, 95% CI were 0.461-0.988 and 0.525-0.968, respectively), adjusted OR for dominant model was 0.702, 95% CI was 0.526-0.937. For rs967591, AA genotype (adjusted OR = 0.721, 95% CI = 0.532-0.978) and at least one A allele (GA+AA) (adjusted OR = 0.716, 95% CI = 0.536-0.956) were significantly correlated with lower risk of NSCLC, compared with GG genotype. But we didn't find correlation between the two SNPs and survival time in Chinese non-smoking NSCLC females. In general, we found PPP1R13L rs1005165 and CD3EAP rs967591 might be associated with lower NSCLC risk in Chinese non-smoking females, but no significant relationship was found with NSCLC survival.

Genetic polymorphisms in 19q13.3 genes associated with alteration of repair capacity to BPDE-DNA adducts in primary cultured lymphocytes

Benzo[a]pyrene(B[a]P), and its ultimate metabolite Benzo[a]pyrene 7,8-diol 9,10-epoxide (BPDE), are classic DNA damaging carcinogens. DNA damage in cells caused by BPDE is normally repaired by Nucleotide Excision Repair (NER) and Base Excision Repair (BER). Genetic variations in NER and BER can change individual DNA repair capacity to DNA damage induced by BPDE. In the present study we determined the number of in vitro induced BPDE-DNA adducts in lymphocytes, to reflect individual susceptibility to Polycyclic aromatic hydrocarbons (PAHs)-induced carcinogenesis. The BPDE-DNA adduct level in lymphocytes were assessed by high performance liquid chromatography (HPLC) in 281 randomly selected participants. We genotyped for 9 single nucleotide polymorphisms (SNPs) in genes involved in NER (XPB rs4150441, XPC rs2228001, rs2279017 and XPF rs4781560), BER (XRCC1 rs25487, rs25489 and rs1799782) and genes located on chromosome 19q13.2-3 (PPP1R13L rs1005165 and CAST rs967591). We found that 3 polymorphisms in chromosome 19q13.2-3 were associated with lower levels of BPDE-DNA adducts (MinorT allele in XRCC1 rs1799782, minor T allele in PPP1R13L rs1005165 and minor A allele in CAST rs967571). In addition, a modified comet assay was performed to further confirm the above conclusions. We found both minor T allele in PPP1R13L rs1005165 and minor A allele in CAST rs967571 were associated with the lower levels of BPDE-adducts. Our data suggested that the variant genotypes of genes in chromosome 19q13.2-3 are associated with the alteration of repair efficiency to DNA damage caused by Benzo[a]pyrene, and may contribute to enhance predictive value for individual's DNA repair capacity in response to environmental carcinogens.

Focused screening of a panel of cancer-related genetic polymorphisms reveals new susceptibility loci for pediatric acute lymphoblastic leukemia

BACKGROUND

A genetic predisposition to acute lymphoblastic leukemia (ALL) in childhood is well established. Currently known risk loci, however, explain only one third of the estimated total risk related to common genetic variations.

PROCEDURE

We genotyped 1,421 polymorphisms in 407 candidate genes from the SNP500Cancer database (National Cancer Institute) using the Illumina Cancer SNP Panel. We investigated 78 cases (aged 0-19 years at diagnosis, and mixed ethnic background) of childhood B-precursor ALL and compared genotype data with those of 1,417 HapMap controls. To account for the ethnic diversity of the study population, structured association by genetically matching cases and controls using identity-by-state similarity was used. Case-control association analyses were performed using Cochran-Mantel-Haenszel tests, adjusted for the population substructure.

RESULTS

Common variations rs6966 (3' UTR of PPP1R13L, chr 19q13.32, P = 4.55 × 10(-9)) and rs414580 (intron 2 of MSR1, chr 8p22, P = 6.09 × 10(-8)) were significantly associated with ALL. These SNPs remained significant after adjustment for multiple testing. The SNP rs6966 tags a haplotype block which includes SNPs in PPP1R13L and ERCC2 genes, which are related to DNA repair and cell survival. rs6966 and rs414580 conferred allelic odds ratios of 3.74 (95% confidence interval [CI] 2.31-6.04) and 3.93 (95% CI 2.31-6.69), respectively.

CONCLUSIONS

These findings reveal two independent novel susceptibility loci for childhood ALL.