Zhengfeng Xu

Functional variant in microRNA-196a2 contributes to the susceptibility of congenital heart disease in a Chinese population†

Hox gene clusters play an important role during cardiac septation to valve formation in different species, and the miR‐196a‐HOXB8‐Sonic hedgehog signaling pathway is of particular interest. Recently, we found that a genetic variant of rs11614913 in the miR‐196a2 sequence could alter mature miR‐196a expression and target mRNA binding; this observation led us to hypothesize that rs11614913 might influence susceptibility to sporadic congenital heart disease (CHD). We conducted a three‐stage case–control study of CHD in Chinese to test our hypothesis by genotyping miR‐196a2 rs11614913 and three other pre‐miRNA SNPs (miR‐146a rs2910164, miR‐149 rs2292832, and miR‐499 rs3746444) in 1,324 CHD cases and 1,783 non‐CHD controls. We found that rs11614913 CC was associated with a significantly increased risk of CHD in all three stages combined (P=6.81×10−6). In a genotype–phenotype correlation analysis using 29 cardiac tissue samples of CHD, rs11614913 CC was associated with significantly increased mature miR‐196a expression (P=0.001). In vitro binding assays further revealed that the rs11614913 variant affects HOXB8 binding to mature miR‐196a. This is the first study to indicate that miR‐196a2 rs11614913 plays a role in sporadic CHD susceptibility. Hum Mutat 30:1–6, 2009.

Mutation analysis of the FLCN gene in Chinese patients with sporadic and familial isolated primary spontaneous pneumothorax

Primary spontaneous pneumothorax (PSP) is a common manifestation of Birt–Hogg–Dubé syndrome caused by folliculin gene (FLCN) mutation, which is also found in isolated familial PSP cases. A complete genetic analysis of FLCN was performed in 102 unrelated Chinese patients with isolated PSP and 21 of their family members. Three novel mutations (c.924_926del, c.1611_1631del and c.1740C>T) and a previously reported mutation (c.1733insC) were identified in five familial and five sporadic PSP patients. Of the 21 family members of patients with PSP including 3 previous considered as sporadic, 4 (19%) had history of at least one episode of PSP and 9 (43%) were FLCN mutant carriers without PSP. Seven of the nine (78%) mutant carriers had pulmonary cysts detected by high‐resolution computed tomography (HRCT). Although c.924_926del and c.1611_1631del were found in eight patients from the same geographic district, haplotype analysis demonstrated that they did not share the same affected haplotype, thus excluding common ancestry. This study first demonstrates that FLCN mutation contributes to not only familial but also ‘apparently sporadic’ patients with isolated PSP. It suggests that mutation analysis and HRCT scan may be recommended for first‐degree family members of PSP patients with FLCN mutations, irrespective of their family history status of PSP.

A genome-wide association study identifies two risk loci for congenital heart malformations in Han Chinese populations

Congenital heart malformation (CHM) is the most common form of congenital human birth anomaly and is the leading cause of infant mortality. Although some causative genes have been identified, little progress has been made in identifying genes in which low-penetrance susceptibility variants occur in the majority of sporadic CHM cases. To identify common genetic variants associated with sporadic non-syndromic CHM in Han Chinese populations, we performed a multistage genome-wide association study (GWAS) in a total of 4,225 CHM cases and 5,112 non-CHM controls. The GWAS stage included 945 cases and 1,246 controls and was followed by 2-stage validation with 2,160 cases and 3,866 controls. The combined analyses identified significant associations (P < 5.0 × 10−8) at 1p12 (rs2474937 near TBX15; odds ratio (OR) = 1.40; P = 8.44 × 10−10) and 4q31.1 (rs1531070 in MAML3; OR = 1.40; P = 4.99 × 10−12). These results extend current knowledge of genetic contributions to CHM in Han Chinese populations.

Parental phenols exposure and spontaneous abortion in Chinese population residing in the middle and lower reaches of the Yangtze River

Widespread use of phenols has led to ubiquitous exposure to phenols. In experimental animals, phenols increased resorptions, reduced live litter size and fetal body weights. However, there are limited epidemiological evidences of the relationships between exposure to phenols and pregnancy outcomes. We evaluated the associations between parental urinary levels of various phenols and spontaneous abortion in a Chinese population residing in the middle and lower reaches of the Yangtze River. A case-control study was conducted that included 70 case couples with medically unexplained spontaneous abortion and 180 control couples who did not have a history of spontaneous abortion and had at least one living child. Both parental urinary phenols were measured by ultra-high performance liquid chromatography-tandem mass spectrometry including bisphenol A (BPA), benzophenone-3 (BP-3), 2,3,4-trichlorophenol (2,3,4-TCP), pentachlorophenol (PCP), 4-n-octylphenol (4-n-OP) and 4-n-nonylphenol (4-n-NP). Compared with the low exposure group, there was an increased risk of spontaneous abortion with high paternal urinary PCP concentration [odds ratio (OR)=2.09, 95% Confidence Interval (CI), 1.05-4.14], and maternal exposure to 4-n-OP and alkylphenol(s) also significantly increased the risk of spontaneous abortion (OR=2.21, 95% CI, 1.02-4.80; OR=2.81, 95% CI, 1.39-5.65, respectively). Our study firstly provides the evidence that paternal PCP exposure, maternal 4-n-OP and alkylphenol(s) exposure are associated with spontaneous abortion in humans.

Genome-wide analysis of runs of homozygosity identifies new susceptibility regions of lung cancer in Han Chinese

Runs of homozygosity (ROHs) are a class of important but poorly studied genomic variations and may be involved in individual susceptibility to diseases. To better understand ROH and its relationship with lung cancer, we performed a genome-wide ROH analysis of a subset of a previous genome-wide case-control study (1,473 cases and 1,962 controls) in a Han Chinese population. ROHs were classified into two classes, based on lengths, intermediate and long ROHs, to evaluate their association with lung cancer risk using existing genome-wide single nucleotide polymorphism (SNP) data. We found that the overall level of intermediate ROHs was significantly associated with a decreased risk of lung cancer (odds ratio = 0.63; 95% confidence interval: 0.51-0.77; P = 4.78×10−6 ), while the long ROHs seemed to be a risk factor of lung cancer. We also identified one ROH region at 14q23.1 that was consistently associated with lung cancer risk in the study. These results indicated that ROHs may be a new class of variation which may be associated with lung cancer risk, and genetic variants at 14q23.1 may be involved in the development of lung cancer.

Interleukin 12B rs3212227 T > G polymorphism was associated with an increased risk of gastric cardiac adenocarcinoma in a Chinese population.

Gastric cardiac adenocarcinoma (GCA) is one of common malignant tumors in the world. Multiple genes that play critical roles in inflammatory pathways probably are associated with GCA risk. We conducted a hospital-based case-control study to evaluate the genetic effects of functional single nucleotide polymorphisms (SNPs): interleukin 9 (IL9) rs31563 C > T, IL9 rs31564 G > T, IL10 rs1800872 T > G, IL12A rs2243115 T > G, IL12B rs3212227 T > G, and IL13 rs1800925 C > T on the development of GCA. Two hundred and forty-three GCA cases and 476 controls were recruited. Their genotypes were determined using a custom-by-design 48-Plex SNPscan kit. IL12B rs3212227 T > G polymorphism was associated with the increased risk of GCA. However, there was no significant association between the other five SNPs and GCA risk. Stratified analyses indicated that the risk of GCA associated with the IL12B rs3212227 T > G polymorphism was evident among female patients and patients who never smoked or consumed alcoholic drinks. These findings indicated that functional polymorphism IL12B rs3212227 T > G might correlate with GCA risk. However, our results were obtained with a limited sample size; the power of our analysis was low. Larger studies are required to confirm the current findings.

1q25.2-q31.3 Deletion in a female with mental retardation, clinodactyly, minor facial anomalies but no growth retardation

The reports of 1q25-32 deletion cases are rare. We reported here an 11-year-old Chinese Han female with an interstitial 1q25 deletion displaying mental retardation, clinodactyly of the 5th finger and minor facial anomalies. Notably, the patient did not present growth retardation which is quite common in patients with 1q25-32 deletion encompassing LHX4. The heterozygous deletion in this patient was characterized as 46,XX,del(1)(q25.2-q31.3) with a length of 20.5 Mb according to SNP-array test results. STRP (Short Tandem Repeat Polymorphism) analysis of the family trio indicated the genomic abnormality was de novo with paternal origin. After a genotype-phenotype analysis, we proposed here the loss of a 3.1 Mb critical region including 24 genes within 1q25.2 (chr1:174.5-177.6 Mb, build 36) may account for the mental retardation in patients with 1q25-32 deletion.

Clinical application of SNP array analysis in first‐trimester pregnancy loss: a prospective study

Chromosomal microarray analysis (CMA) has been used routinely in pediatric and prenatal genetic diagnosis in clinical practice, but it has rarely been applied to miscarriage analysis. In this study, we conducted a prospective study to evaluate the feasibility of CMA for genetic diagnosis of first‐trimester miscarriage specimens. We successfully analyzed 551 fresh miscarriage specimens using single‐nucleotide polymorphism (SNP) array. Among the specimens, 2.9% (16/551) had significant maternal cell contamination and were excluded from the study. Clinically significant chromosomal abnormalities were identified in 295 (55.1%) cases, including 214 (40%) with aneuploidy, 40 (7.5%) with polyploidy, 19 (3.6%) with partial aneuploidy, 12 (2.2%) with pathogenic microdeletion/microduplication, and 10 (1.9%) with uniparental isodisomy (isoUPD). Variants of uncertain significance were obtained in 15 cases (2.8%). Notably, isoUPD involving a single chromosome (chromosome 22) and two recurrent copy number variations, 22q11.2 microdeletion and 7q11.23 microdeletion, were identified as probably to be associated with miscarriage. The frequency and distribution of genetic aberrations in the spontaneous abortion group was not significantly different from those in the recurrent miscarriage group. Our study suggests SNP array is a reliable, robust, and high‐resolution technology for genetic diagnosis of miscarriage in clinical practice.

Novel missense variants of ZFPM2/FOG2 identified in conotruncal heart defect patients do not impair interaction with GATA4.

Conotruncal heart defect (CTD) is a complex form of congenital heart disease and usually has a poor prognosis. ZFPM2/FOG2 encodes a transcription cofactor that interacts with GATA4 to regulate cardiac development. This regulation has been established in knockout mouse models that display a range of heart malformations, especially CTD. Although previous studies have identified several missense variants in ZFPM2/FOG2 that may cause CTD, it remains unclear whether they are involved in CTD pathogenesis because the study populations were limited and the functional status was unknown. In this report, we screened a larger CTD population, which comprised 145 tetralogy of Fallot (TOF), 37 double-outlet ventricle outflow (DORV), and 18 transposition of the great artery (TGA), to investigate exon mutations as well as copy number variations in ZFPM2/FOG2. Four variants (p.V339I in one DORV, p.A426T in one DORV, p.M703L in three TOF, p.T843M in one TOF) were found in six patients, of which two are reported here for the first time. No copy number variations of the gene were detected. GST pull-down assays demonstrated that all potentially deleterious variants, including those previously reported, did not impair the interaction with GATA4, except for variant p.M544I and p.K737E, which subtly impaired the binding. Thus, these missense variants may be involved in other mechanisms underlying CTD or may be unrelated to CTD occurrence.

Molecular analysis of the CYP21A2 gene in Chinese patients with steroid 21-hydroxylase deficiency

OBJECTIVE 21-Hydroxylase deficiency (21-OHD) is the most common cause of congenital adrenal hyperplasia (CAH), a family of autosomal recessive disorders involving impaired cortisol synthesis. This study aimed to design a reliable and rational approach for identifying mutations in the CYP21A2 gene and to characterize the molecular basis of 21-OHD in 30 Chinese patients. DESIGN AND METHODS Copy number variations were investigated by multiplex ligation-dependent probe amplification (MLPA). Locus-specific polymerase chain reaction (PCR)/restriction endonuclease analysis was then used to verify CYP21A2 rearrangement products and prevent allele dropout. Direct sequencing of rearrangement products was performed to further refine recombination breakpoint locations. Direct sequencing of the entire CYP21A2 gene was used to detect microconversions. RESULTS We successfully characterized 60 CYP21A2 alleles from 30 patients with genetic defects. The most common one was intron 2 splice mutation (38.3%). Eighteen alleles with large gene deletions/conversions were identified, which accounted for nearly one-third (30.0%) of the genetic defects. Among these, three types of CYP21A1P/CYP21A2 chimeric genes (CH-1, CH-2, and CH-4) were characterized. Two novel CYP21A2 rearrangement genes were revealed and further demonstrated to be located downstream of the TNXB gene. CONCLUSIONS Our results indicate that the stepwise diagnostic procedure involving MLPA analysis, locus-specific PCR/restriction endonuclease analysis, and direct DNA sequencing can provide detailed genetic information about Chinese 21-OHD patients, which is helpful for characterizing structural rearrangements of CYP21A2.