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PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Yellow and red asterisks: non-risk and risk allele, respectively.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
b Scatter dot plot showing (black dots) 65 SNPs with significant allele-specific effects on reporter activity in the MPRA and (gray dots) 822 SNPs without them.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Arrows indicate the functional SNPs identified in this study (two near IRF6, rs11119348 and rs661849, and one near FOXE1, rs10984103).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Dashed lines indicate the 95th percentile of the reporter activity of scrambled elements; on both axes, zero, i.e., log2(1) represents the reporter activity of the empty vector.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
The number of SNPs tested, and the number with allele-specific effects, in the MPRA at each locus In the MPRA results we assessed the enhancer activity of each element and whether the SNP allele affected it.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Of the 887 elements evaluated, one or both variants of 480 (54.1%) had activity significantly different from that of the basal promoter (false discovery rate (FDR) <0.01); 180 (20.3%) of them exhibited higher activity than that of the basal promoter (Supplementary Data 6 and Supplementary Fig. 1b).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
As expected, the average activity of 84 scrambled genomic test elements was very close to that to the basal promoter (Supplementary Fig. 1c and Supplementary Data 7).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Unexpectedly, the enhancer activities of the test elements were only weakly correlated with levels of histone H3 lysine 27 acetylation (H3K27Ac), a mark of active enhancers, in primary normal human epidermal keratinocytes (NHEK) (Pearson correlation coefficient r = 0.1126) (Supplementary Fig. 1d).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Further, the enhancer activities of four elements from within a known oral epithelium enhancer (IRF6 MCS9.7) were not higher than that of the basal promoter (Supplementary Fig. 1c).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
These unexpected findings may reflect the semi-epithelial phenotype of this cell line, discussed below.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Nonetheless, 65 (7%) of the SNPs tested had allele-specific enhancer activity in the MPRA (Fig. 1b and Supplementary Data 6) (FDR <0.05), nominating these SNPs as candidates to be functional.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
These SNPs were enriched among elements whose activity was different from that of the basal promoter (P < 0.0001, one-sided Fisher’s exact test).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Each of the eight loci had at least one of the 65 MPRA-nominated SNPs; notably, at the 1q32/IRF6 locus, there were 46 such SNPs (Figs. 1b, 2a, Table 1, and Supplementary Data 6).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
We filtered MPRA-nominated SNPs for those lying within enhancers active in embryonic oral epithelium.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
In one approach to identify such enhancers, we used NHEKs as a model for embryonic oral epithelium and the activity-by-contact (ABC) method to identify enhancers for the presumed effector genes.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
This method incorporates cell type-specific RNA-seq, DNAse hypersensitivity, and H3K27Ac ChIP-seq datasets, all of which are available for NHEKs, and averaged HiC chromatin-contact data from ten ENCODE cell types.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Two apparent enhancers for IRF6 and one for FOXE1 contained MPRA-nominated SNPs (i.e., rs11119348 and rs661849 near IRF6, rs10984103 near FOXE1) (Fig. 2a–c).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
The first candidate SNP near IRF6, rs11119348, lies within IRF6 MCS9.7.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
This element is the site of a rare single-base-pair duplication that appears to cause Van der Woude syndrome.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
It also contains three other common SNPs (i.e., in addition to rs11119348) that are associated with non-syndromic OFC, including rs642961, the focus of an earlier study.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
We tested all four of these common SNPs (separately) in the MPRA but only rs11119348 had allele-specific effects in it (Supplementary Fig. 1c).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
We will refer to this as the “IRF6 −10 kb SNP” (Fig. 2b).Fig.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
2Two SNPs (rs11119348 and rs661849) at IRF6 and one SNP (rs10984103) at FOXE1 as regulatory variants.a–c UCSC browser views of the human genome, GRCh37/hg19, focused on the OFC-associated SNPs at a, b IRF6 and c FOXE1.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
OFC SNPs, SNPs identified by GWAS and evaluated by MPRA at each locus.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
One SNP at the FOXE1 locus, which was tested in the MPRA but lacked significant effects in it, rs1877431, is outside of the range presented here.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
MPRA-sig SNPs, SNPs with allele-specific effects in the MPRA.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
IRF6 enhancers, FOXE1 enhancers, and enhancers for the indicated gene identified using the activity-by-contact (ABC) method and datasets from NHEK (see Methods).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Gray arrows, GWAS-meta-analysis P values of the indicated SNPs.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Two-sided P values are calculated with an inverse-variance weighted fixed-effects meta-analysis of a transmission disequilibrium test without adjustment for multiple testing and a logistic regression (that had 18 principal components of ancestry as covariates).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
GM12878 B-cell derived cell line, H1-ESC embryonic stem cells, K562 myelogenous leukemia cell line, HepG2 liver cancer cell line, HUVEC human umbilical vein endothelial cells, HMEC human mammary epithelial cells, HSMM human skeletal muscle myoblasts, NHEK normal human epidermal keratinocytes, NHLF normal human lung fibroblasts.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
CS 13-20, Carnegie stages for human embryonic face explants.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Colored bars, inferred chromatin state from combinatorial analysis of multiple chromatin mark datasets.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Orange and yellow, active and weak enhancer element, respectively; bright red, active promoter; light red, weak promoter; purple, inactive/poised promoter; blue, insulator; light green, weakly transcribed; gray, Polycomb repressed; light gray, heterochromatin/repetitive.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Additional color bars in the facial explants dataset, green, transcription; green-yellow, transcription weak enhancer; purple, bivalent promoter; light purple, poised promoter.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
a–c UCSC browser views of the human genome, GRCh37/hg19, focused on the OFC-associated SNPs at a, b IRF6 and c FOXE1.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
OFC SNPs, SNPs identified by GWAS and evaluated by MPRA at each locus.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
One SNP at the FOXE1 locus, which was tested in the MPRA but lacked significant effects in it, rs1877431, is outside of the range presented here.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
MPRA-sig SNPs, SNPs with allele-specific effects in the MPRA.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
IRF6 enhancers, FOXE1 enhancers, and enhancers for the indicated gene identified using the activity-by-contact (ABC) method and datasets from NHEK (see Methods).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Gray arrows, GWAS-meta-analysis P values of the indicated SNPs.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Two-sided P values are calculated with an inverse-variance weighted fixed-effects meta-analysis of a transmission disequilibrium test without adjustment for multiple testing and a logistic regression (that had 18 principal components of ancestry as covariates).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
GM12878 B-cell derived cell line, H1-ESC embryonic stem cells, K562 myelogenous leukemia cell line, HepG2 liver cancer cell line, HUVEC human umbilical vein endothelial cells, HMEC human mammary epithelial cells, HSMM human skeletal muscle myoblasts, NHEK normal human epidermal keratinocytes, NHLF normal human lung fibroblasts.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
CS 13-20, Carnegie stages for human embryonic face explants.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Colored bars, inferred chromatin state from combinatorial analysis of multiple chromatin mark datasets.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Orange and yellow, active and weak enhancer element, respectively; bright red, active promoter; light red, weak promoter; purple, inactive/poised promoter; blue, insulator; light green, weakly transcribed; gray, Polycomb repressed; light gray, heterochromatin/repetitive.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Additional color bars in the facial explants dataset, green, transcription; green-yellow, transcription weak enhancer; purple, bivalent promoter; light purple, poised promoter.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
The second candidate SNP in this locus, rs661849, resides within an evolutionarily conserved sequence 21.7 kb upstream of the IRF6 promoter and within the UTP25 promoter (Fig. 2b).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
There are no other OFC-associated SNPs within this element.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
We will refer to rs661849 as the “IRF6 −22 kb SNP”.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
This SNP is an expression QTL (eQTL) in GTEx for several genes and tissues in the region, including IRF6 in cerebellum (P value = 1.5e-8), and is a splicing QTL (sQTL) for IRF6 in sun-exposed skin (P value = 8.3e-9) and for neighboring gene TRAF3IP3 in whole blood.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Of note, rs642961, mentioned above, is in linkage disequilibrium with the IRF6 −22 kb SNP (R = 0.769) but not with the IRF6 −10 kb SNP (R = 0.033) (based on data from the 1000 Genomes project) (Supplementary Fig. 2 and Supplementary Data 8).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
The candidate SNP within a FOXE1 enhancer, rs10984103, lies within a predicted enhancer 23.8 kb downstream of the FOXE1 transcription start site (Fig. 2c).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
This SNP is an eQTL for FOXE1 in multiple tissues, including the testis, esophageal mucosa, nerve, and cerebellum.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
We will refer to this SNP as the “FOXE1 24 kb SNP”.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
In a second, broader approach to identify potential embryonic oral epithelium enhancers that is agnostic to the identity of the effector gene we used chromatin-mark evidence of enhancers active (1) in NHEK (ENCODE), (2) in human immortalized oral epithelial cells (HIOEC), which are potentially a better model of embryonic oral epithelium than NHEK, or (3) in human embryonic faces.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Within elements marked as enhancers in one or more of these contexts there were fourteen MPRA-nominated SNPs, including the three discussed above (Fig. 2b, c); the additional SNPs were detected in the 1q32/IRF6, 6p24.3/TFAP2A, 3q28/TP63, and 20q12/MAFB loci (Supplementary Data 9 and Supplementary Figs. 3–9).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
In summary, intersecting MPRA-nominated SNPs with predicted enhancers strengthened the candidacy of 14 SNPs as being functional (Table 1 and Supplementary Data 9).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
We next tested a subset of the MPRA results in traditional luciferase reporter assays in GMSM-K cells, using reporter elements arbitrarily chosen to be 701 bp long and centered on the SNP (Fig. 3a and Supplementary Data 10, 11).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
For these tests, we picked six SNPs with allele-specific effects in the MPRA and seven SNPs without them.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
The former were all among the fourteen candidates discussed above and included IRF6 −10 kb, IRF6 −22 kb, FOXE1 24 kb, rs4812449 (near MAFB), rs201265 (near TFAP2A), and rs75436877 (near TP63); the latter included rs642961 within IRF6 MCS9.7.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
All six SNPs with allele-specific effects in the MPRA also had them in the luciferase reporter assays, although in two cases, FOXE1 24 kb and rs201265 (near TFAP2A), the direction of effect was reversed (Fig. 3a and Supplementary Data 11, 12).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Discordance in the direction of effects of SNP alleles between traditional reporter assays and MPRA has been reported in other studies and presumably reflects that the short elements used in MPRAs are not full-sized enhancers (addressed below).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Among the seven SNPs that did not have allele-specific effects in the MPRA, five also did not have them in the luciferase reporter assays.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
These five included rs642961 within IRF6 MCS9.7, in agreement with a previous report.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
In summary, for eleven of thirteen SNPs tested, luciferase reporter assays agreed with MPRA regarding whether enhancer activity was affected by a SNP allele; this rate of concordance between luciferase and MPRA results is significant (P = 0.0163, one-sided Fisher’s exact test) and matches or exceeds that of other studies using MPRAs to detect functional non-coding SNPs.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Fig. 3Two SNPs at IRF6 and one SNP at FOXE1 have allele-specific effects on enhancer activities and expression levels of the adjacent OFC risk-associated genes.a Bar chart of MPRA and luciferase reporter activities for the indicated SNPs at various loci in GMSM-K using elements of the indicated length centered on the SNP.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
MPRA data are represented as mean ± standard error of the mean (SEM) from the indicated number of replicates.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) of the difference between major and minor allele’s reporter activity is determined by Welch’s t-test, followed by Benjamini–Hochberg false discovery rate correction.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
P (MPRA) = 0.0452 (rs11110348), 0.0057 (rs661849), 0.9097 (rs642961), 0.6942 (rs4844939), 0.4487 (rs12104876), 0.0238 (rs75436877), 0.7100 (rs79482068), 0.0734 (rs79792381), 0.0125 (rs201265), 0.1206 (rs10124184), 0.0067 (rs10984103), 0.0458 (rs4812449), 0.2945 (rs57369620).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
For luciferase reporter activities, data are represented as mean ± standard deviation (SD) from four independent experiments.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) is determined by Student’s t-test.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
P (luciferase) = 0.0006 (rs11110348), <0.0001 (rs661849), 0.3822 (rs642961), <0.0001 (rs4844939), 0.14 (rs12104876), <0.0001 (rs75436877), 0.0693 (rs79482068), 0.5115 (rs79792381), 0.002 (rs201265), <0.0001 (rs10124184), <0.0001 (rs10984103), <0.0001 (rs4812449), 0.1421 (rs57369620). *
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, NS non-significant.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
b–d Scattered dot plots of relative luciferase activity (using the longer elements described in Results) for non-risk and risk alleles of rs11119348, rs661849 and rs10984103 in primary neonatal keratinocytes (HEKn).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Value of 1 is that of the empty pGL3 promoter vector.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Data are represented as mean ± standard deviation (SD) from four independent experiments.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) is determined by Student’s t-test and P value is indicated on the plot.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
e–g Scattered dot plot of relative levels of e, f IRF6 or g FOXE1 mRNA in edited induced oral epithelium (iOE) cells homozygous for the non-risk or risk alleles of each SNP, as indicated, assessed by qRT-PCR.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Expression levels are normalized against those of ACTB, GAPDH, HPRT1, UBC and CDH1.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Data were represented as mean ± SD from e, f six replicates or g nine replicates of cells harboring each genotype, as indicated in the plot.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Each dot represents three technical qPCR replicates.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) is determined by Student’s t-test and P value is indicated on the plot.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Source data are provided as a Source Data file.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
a Bar chart of MPRA and luciferase reporter activities for the indicated SNPs at various loci in GMSM-K using elements of the indicated length centered on the SNP.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
MPRA data are represented as mean ± standard error of the mean (SEM) from the indicated number of replicates.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) of the difference between major and minor allele’s reporter activity is determined by Welch’s t-test, followed by Benjamini–Hochberg false discovery rate correction.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
P (MPRA) = 0.0452 (rs11110348), 0.0057 (rs661849), 0.9097 (rs642961), 0.6942 (rs4844939), 0.4487 (rs12104876), 0.0238 (rs75436877), 0.7100 (rs79482068), 0.0734 (rs79792381), 0.0125 (rs201265), 0.1206 (rs10124184), 0.0067 (rs10984103), 0.0458 (rs4812449), 0.2945 (rs57369620).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
For luciferase reporter activities, data are represented as mean ± standard deviation (SD) from four independent experiments.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) is determined by Student’s t-test.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
P (luciferase) = 0.0006 (rs11110348), <0.0001 (rs661849), 0.3822 (rs642961), <0.0001 (rs4844939), 0.14 (rs12104876), <0.0001 (rs75436877), 0.0693 (rs79482068), 0.5115 (rs79792381), 0.002 (rs201265), <0.0001 (rs10124184), <0.0001 (rs10984103), <0.0001 (rs4812449), 0.1421 (rs57369620). *
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, NS non-significant.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
b–d Scattered dot plots of relative luciferase activity (using the longer elements described in Results) for non-risk and risk alleles of rs11119348, rs661849 and rs10984103 in primary neonatal keratinocytes (HEKn).
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Value of 1 is that of the empty pGL3 promoter vector.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Data are represented as mean ± standard deviation (SD) from four independent experiments.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) is determined by Student’s t-test and P value is indicated on the plot.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
e–g Scattered dot plot of relative levels of e, f IRF6 or g FOXE1 mRNA in edited induced oral epithelium (iOE) cells homozygous for the non-risk or risk alleles of each SNP, as indicated, assessed by qRT-PCR.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Expression levels are normalized against those of ACTB, GAPDH, HPRT1, UBC and CDH1.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Data were represented as mean ± SD from e, f six replicates or g nine replicates of cells harboring each genotype, as indicated in the plot.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Each dot represents three technical qPCR replicates.
PMC12267437
Identification of functional non-coding variants associated with orofacial cleft
Statistical significance (P value, two-tailed) is determined by Student’s t-test and P value is indicated on the plot.