[Associations between vitamin D levels and systemic lupus erythematosus risk:a Mendelian randomized study].

Objective: To explore the causal effects of the serum Vitamin D levels on the risk of systemic lupus erythematosus (SLE). Methods: A two-sample Mendelian randomization (MR) study was performed to infer the causality. Three Genome-wide association studies (GWAS) for circulating Vitamin D levels, including 25-hydroxyvitamin D [25(OH)D], 25-hydroxyvitamin D3 [25(OH)D3] and C3-epimer of 25-hydroxyvitamin D3 [C3-epi-25(OH)D3] published in 2020, and one GWAS for SLE published in 2015 were utilized to analyze the causal effects of the serum Vitamin D levels on the risk of SLE. MR analyses were conducted using the inverse-variance weighted method (IVW), weighted median, MR-Egger methods, MR-pleiotropy residual sum and outlier (MR-PRESSO) method. Results: 34, 29 and 6 SNPs were respectively selected as instrumental variables to analyze the causal association of total 25 (OH) D level, 25 (OH) D3 level and C3-epi-25 (OH) D3 level with the risk of SLE. The MR results showed that each standard deviation decrease in the level of 25(OH)D3 would result in 14.2% higher risk of SLE (OR, 0.858; 95%CI, 0.753-0.978; P=0.022). The levels of 25(OH)D and C3-epi-25(OH)D3 had null associations with risk of SLE (OR, 0.849; 95%CI, 0.653-1.104; P=0.222; OR, 0.904; 95%CI, 0.695-1.176; P=0.452). Conclusion: This study have identified a causal effect of 25(OH)D3 on increased risk of SLE. These findings highlighted the significance of active monitoring and prevention of SLE in population of low Vitamin D levels.

[Clinical evaluation of antral septal maxillary sinus floor elevation by the disk-up sinus reamer].

Objective: To investigate the clinical effect of disk-up sinus reamer (DSR) in maxillary sinus floor elevation with maxillary sinus septum. Methods: Twenty-four patients were included between January 2019 to January 2020 in Department of Oral Implantology, The Affiliated Hospital of Qingdao University. There were 10 males and 14 females with the age of (39.3±11.7) years old (range 22-56 years). Pre-operative(T0) cone-beam CT (CBCT) was taken for measurement and analysis. All patients were divided into group E (easy situations, septum located anterior to the zygo-matic process), group M (moderate situations, septum located pos-terior to the zygo-matic process) and group D (difficult situations, sagittally oriented septum). The maxillary sinus floor was grafted through the crestal approach by DSR and implants were placed simultaneously. Permanent repair was performed 6-8 months after operation. All patients underwent CBCT before surgery, after surgery immediately (T1), 6 months after surgery(T2), 1 year after surgery(T3), 2 year after surgery(T4). The residual bone height (RBH) and the vertical bone height (VBH) were analyzed. The mucosal perforation rate, implant survival rate were counted. Results: All the 24 patients completed the Maxillary sinus lift surgery successfully and 24 implants were placed simultaneously. All patients had no headache, dizziness. The mucosal perforation rate was 0. The survival rate of implants during the healing period was 100%(24/24). The RBH was (5.81±2.56) mm pre-operation, the VBHT1, VBHT2, VBHT3 and VBHT4 were (11.82±1.09), (10.98±0.52), (10.66±0.44) and (10.40±0.33) mm, respectively. The differences between the groups by pairing test were statistically significant (F=187.70, P0.001), expect VBHT3 and VBHT4 (P=0.071). Bone resorption and remodeling mainly occurred 1 year after surgery. One patient developed peri-implantitis 18 months after surgery. Conclusions: With the RBH of implant site>2 mm and existence of maxillary sinus septum, using DSR for sinus floor elevation has a high success rate. It can obtain enough bone height and complete the simultaneous implantation to form a good osseointegration. The DSR is simple, safe and controllable, and can shorten the operation time.

[Analysis of risk factors of central nervous system complications supported on extracorporeal membrane oxygenation].

Objective: To investigate the risk factors of central nervous system (CNS) complications in children undergoing extracorporeal membrane oxygenation (ECMO) support. Methods: The clinical data, ECMO parameters, laboratory examination and outcome (follow-up to 90 d after discharge) of 82 children treated with ECMO in the pediatric intensive care unit (PICU) of Shanghai Children's Hospital from December 2015 to December 2021 were analyzed retrospectively in this study. The patients were divided into CNS complication group and non-CNS complication group. The ECMO mode, ECMO catheterization mode, clinical and laboratory indicators pre-ECMO and 24 h after ECMO initiation, in-hospital mortality and 90-day mortality were compared with Chi-square test, t test and nonparametric rank sum test. Kaplan-Meier method was used to draw survival curve, and Log-rank test was used to compare the difference in survival rate. The receiver operating characteristic (ROC) curve was used to evaluate the power of variables to predict CNS complications. Results: A total of 82 children were treated with ECMO, including 49 males and 33 females, aged 34 (8, 80) months. There were 18 cases suffering CNS complications, including cerebral hemorrhage in 8 cases, epilepsy in 6 cases, simple cerebral infarction in 3 cases, and cerebral hemorrhage combined with cerebral infarction in 1 case. Veno-arterial ECMO accounted for a greater proportion in CNS complication group (17/18 vs. 67% (43/64), χ2=4.02, P=0.045). A higher percentage of children with CNS complications underwent surgical cannulation compared to those in non-CNS complication group (16/18 vs. 53% (34/64), χ2=7.55, P=0.006). The laboratory results indicated that lower pre-ECMO pH value (7.24 (7.15, 7.28) vs. 7.35 (7.26, 7.45), Z=-3.65, P<0.001) and platelet count 24 h after ECMO initiation (66 (27, 135) ×109/L vs. 107 (61, 157) ×109/L, Z=-2.04, P=0.041) were associated with CNS complications. In the CNS complication group, 7 children died during hospitalization and 7 died during 90-day after admission, and there was no significant difference compared with those in the non-CNS complication group (7/18 vs. 31% (20/64), 7/18 vs. 34% (22/64), both P>0.05). The ROC curve analysis indicated that the area under the ROC curve for pre-ECMO pH value was 0.738 (95%CI 0.598-0.877), and the optimal cut-off value was 7.325. Conclusions: CNS complications in children undergoing ECMO support are common. Pre-ECMO pH value <7.325 is a risk factor for CNS complications. Reducing the veno-arterial ECMO and surgical cannulation can help reduce the occurrence of CNS complications.

[Clinical features and outcomes of pediatric acute fulminant myocarditis requiring extracorporeal membrane oxygenation].

Objective: To observe the clinical features and effects of extracorporeal membrane oxygenation (ECMO) in critically ill children with acute fulminant myocarditis (AFM). Methods: A retrospective analysis was performed in pediatric patients with AFM requiring ECMO, from December 2015 to December 2018, who were admitted to the Pediatric Intensive Care Unit (PICU) in Shanghai Children's Hospital. According to whether patient was alive at least 48 hours after weaning, the children were divided into successful weaning group (9 cases) and unsucessful weaning group (3 cases). The factors related to successful ECMO weaning were explored. The changes of clinical and biochemical parameters before and after ECMO treatment in successful weaning group were analyzed. Continuous variables were presented as median (inter quartile range) for abnormal distribution data, and Mann-Whitney U test was used to compare the data. Results: A total of 12 pediatric patients including 4 males and 8 females were enrolled in this study. The median body weight was 20 (17, 36) kg, and the median age was 66 (48, 103) months. Nine cases were successfully weaned from ECMO, and 8 cases survived to discharge, and 4 cases died in the hospital. The median interval between symptoms onset and ECMO establishment was 3.0 (2.2, 4.0) days, the median duration of ECMO support was 120 (68, 152) hours. In the unsuccessful weaning group, patients displayed higher levels of initiallactic acid (LA), higher vasoactive-inotropic score (VIS), and longer QRS duration before ECMO establishment when compared with those in the successful weaning group (all P<0.05). After ECMO establishment, mean arterial pressure (MAP), systemic central venous oxygen saturation, LA, myocardial injury markers and left ventricular ejection fraction were all significantly improved in the successful weaning group (all P<0.05). Conclusion: In pediatric AFM patients, serum LA level, VIS and QRS duration before ECMO establishment are associated with successful ECMO weaning.

[Relationship between continuous renal replacement therapy and hypophosphatemia in critically ill children].

Objective: To investigate the incidence and prognosis of hypophosphatemia in critically ill children treated with continuous blood purification (CBP). Methods: The medical records of the critically ill patients, who were treated with CBP, admitted to pediatric intensive care unit (PICU) of Shanghai Children's Hospital from May 2014 to April 2017 were retrospectively analyzed. The serum phosphorus levels were tested before CBP, at 48-72 h during CBP, at the end of CBP and on the next day after CBP finished. Phosphorus supplement was given to the children with severe hypophosphatemia. Results: A total of 85 patients met the inclusion criteria. The serum phosphorus levels at the 4 indicated time points were (1.4±0.5), (0.7±0.3), (0.8±0.3), (0.9±0.4) mmol/L, respectively (F=45.21, P<0.05). Among the children, 66 cases (78%) had hypophosphatemia during CBP. The incidences of moderate and severe hypophosphatemia were 32 (48%) and 9 (14%), respectively. There were 41 patients with CBP replacement rates of (35-49) ml/(kg·h), while 44 patients with CBP replacement rates of 50-70 ml/(kg·h). There were significant differences at 48-72 h during CBP, the end of CBP and on the next day after CBP ((0.8±0.4) vs. (0.5±0.2), (1.0±0.3) vs. (0.6±0.2), and (1.1±0.4) vs. (0.8±0.2) mmol/L; t=7.672, 4.060, 14.440, P<0.05). Atotal of 9 cases were treated with sodium glycerophosphate. Among the 85 children, 24 (28%) patients died while 61 (72%) survived. There were no significant differences between the two groups in serum phosphorus levels at the indicated time points ((1.4±0.5) vs. (1.4±0.5), (0.7±0.3) vs. (0.7±0.3), (0.7±0.3) vs. (0.8±0.3), and (1.0±0.3) vs. (0.9±0.3) mmol/L, respectively, P>0.05). Conclusions: Hypophosphatemia is prone to occur during CBP, which probably related to the replacement rate. There was no significant relationship between hypophosphatemia and mortality in critically ill children after giving phosphorus supplementation.

Exosomes mediated transfer of lncRNA UCA1 results in increased tamoxifen resistance in breast cancer cells.

OBJECTIVE: In this study, we firstly compared the loading of urothelial carcinoma-associated 1 (UCA1) in exosomes between tamoxifen sensitive and tamoxifen resistant breast cancer cells and further investigated the role of exosomal transfer of UCA1 in the development of tamoxifen resistance in estrogen receptor (ER) positive breast cancer cells. MATERIALS AND METHODS: Exosomes were isolated from the culture medium of tamoxifen sensitive MCF-7 cells and tamoxifen resistant LCC2 cells. QRT-PCR was performed to analyze UCA1 expression in cells and exosomes. CCK-8 assay, immunofluorescence staining of cleaved caspase-3 and flow cytometric analysis of annexin V/PI staining were used to assess tamoxifen sensitivity. RESULTS: UCA1 is significantly increased not only in LCC2 cells, but also in exosomes released from LCC2 cells. The increase in exosomes is more evident than in cells. MCF-7 cells pretreated with exos/LCC2 had a significantly increased cell viability, a decreased expression of cleaved caspase-3 and a lower ratio of apoptosis after tamoxifen treatment. The exos/LCC2 with impaired UCA1 loading had significantly suppressed capability to promote tamoxifen resistance in MCF-7 cells. CONCLUSIONS: UCA1 is significantly loaded in exosomes from tamoxifen resistant LCC2 cells. Exosomes mediated transfer of UCA1 can significantly increase tamoxifen resistance in ER-positive MCF-7 cells.

[Characterization of N-linked glycosylation sites on envelope proteins of simian/human immunodeficiency virus in peripheral blood of Chinese rhesus macaques during acute infection].

Objective: To investigate the number and distribution of N-linked glycosylation sites of simian/human immunodeficiency virus envelope proteins(SHIVSF162P3)and SHIV transmission. Methods: Two female adult Chinese rhesus macaques(4 years old)were intravenously inoculated with 300 TCID50 SHIVSF162P3. The macaques weighed 4 and 5 kg and were identified as Rh1 and Rh2. We collected plasma samples at days 3, 7, 10, 14, 17, 21, 24, 28, 35, 42, 49, 56, 63, 70 and 77 post-challenge. Subsequently, we monitored plasma viral load by real-time PCR after viral RNA isolation and cDNA synthesis. We amplified the full-length envelope gene by single genome amplification(SGA)at days 7, 14, 28 and 77. BioEdit, MEGA, and the HIV Databases were used to analyze envelope sequences. Sequence diversity and N-linked glycosylation sites were compared between virus stock and plasma viruses of the two macaques. Results: A total of 55 env sequences were obtained from virus stock and their average pairwise distances were(0.166 6± 0.096 3)%. Viral loads peaked at 7.68 and 7.49 log10 copies/ml at day 10 and reached the set point at day 42(4.27 and 4.81 log10 copies/ml). The percentages of envelope sequences containing 25 potential N-linked glycosylation sites(PNGSs)were 83%(20/24)and 94%(29/31)in Rh1 and Rh2, respectively, at day 7; these were significantly higher than the proportion in SHIVSF162P3 stock(49%(27/55)). Viral diversity after infection increased with time whereas the proportion of sequences containing 25 PNGSs decreased and sequences containing 27 PNGSs gradually increased. In Rh1, the percentage of sequences containing 27 PNGSs increased to 29% at day 28 and reached 35% at day 77 in Rh2. By analyzing the number of PNGSs in the V1-V5 regions, we found that PNGS variation mainly occurred in the V4 loop. Compared with sequences containing 27 PNGSs, a seven amino acid(TWNNTIG)deletion was found in the V4 loop, which resulted in a loss of two PNGSs at positions 392 and 396. Conclusion: Low glycosylation of the SHIVSF162P3 V4 loop may facilitate spread of the SHIV virus whereas viruses with highly glycosylated V4 loops showed replication advantages after infection.

USF1 prompt melanoma through upregulating TGF-ß signaling pathway.

OBJECTIVE: The activation of TGF-ß signaling contributes to abnormal EMT process and upstream stimulatory family1 (USF1) was recently found to activate the expression of TGF-ß. However, the specific role of USF1 in melanoma has never been explored. MATERIALS AND METHODS: The expression of USF1 was analyzed using real-time PCR and Western blot. The changes of cell morphology were observed under a microscope. Cell migration was determined using in vitro scratch test. A specific siRNA was applied to knockdown of USF1. RESULTS: The mRNA and protein levels of USF1 were significantly enhanced in melanoma cell lines, 1205-Lu, DO4, WM3211, and WM278, compared with normal human melanocytes PIG1. Overexpression of USF1 induced demonstrated an elongated and spindle-shaped morphology in the 1205-Lu cells. Meanwhile, USF1 induced the expression of α-SMA, Vimentin and Fibronectin, while the epithelial marker, E-cadherin (E-cad), was significantly decreased. Furthermore, in vitro scratch test demonstrated that overexpression of USF1 markedly enhanced 1205-Lu cell migration capacity at 24 h and 48 h. More importantly, knockdown of USF1 could partially reverse TGF-ß1-treatment-induced changes of EMT markers as well as cell morphological changes. CONCLUSIONS: We first demonstrate that overexpression of USF1 prompts the EMT process through the accumulation of TGF-ß1 production in melanoma cells.

MiR-18a upregulation enhances autophagy in triple negative cancer cells via inhibiting mTOR signaling pathway.

OBJECTIVE: We investigated the involvement of miR-18a upregulation in autophagy regulation and paclitaxel (PTX) resistance in triple negative breast cancer (TNBC) cells. MATERIALS AND METHODS: PTX resistant MDA-MMB-231/PTX cells were generated using an intermittent, stepwise method. MiR-18a expression was assessed using qRT-PCR. The level of autophagy was assessed by Western blot analysis of LC3B expression and observation of LC3-GFP puncta formation under a fluorescence microscope. The effect of miR-18a mediated autophagy on PTX sensitivity was assessed by measuring IC50 and PTX induced cell apoptosis. RESULTS: MDA-MB-231/PTX cells had both higher miR-18a expression and basal autophagy than MDA-MB-231 cells. Enforced miR-18a overexpression directly led to increased autophagy in MDA-MB-231 cells, the effect of which was similar to that of rapamycin, a mTOR signaling inhibitor. Following Western blot analysis showed that miR-18a overexpression decreased the expression of p-mTOR and p-p70S6. Therefore, we infer that miR-18a increases autophagy level in MDA-MB-231 cells via inhibiting mTOR signaling pathway. Both drug sensitivity assay and flow cytometry analysis confirmed that the effect of miR-18a on increasing IC50 and decreasing PTX induced apoptosis in MDA-MB-231 cells could largely be abrogated by treatment with bafilomycin A1 (Baf. A1). CONCLUSIONS: MiR-18a upregulation results in enhanced autophagy via inhibiting mTOR signaling pathway in TNBC cells, which is a mechanism contributing to paclitaxel resistance.

Inhibition of andrographolide in RAW 264.7 murine macrophage osteoclastogenesis by downregulating the nuclear factor-kappaB signaling pathway.

This study aims to investigate the effects of andrographolide (AGP) on osteoclast formation in RAW 264.7 murine macrophage cells. The effects of AGP on cell viability were determined in RAW 264.7 cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of AGP on osteoclast formation were tested by osteoclast staining with tartrate-resistant acid phosphatase (TRAP). The effects of AGP on receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL)-induced, NF-kappaB-dependent transcription in RAW 264.7 cells were assessed using luciferase reporter assays. The results demonstrated that the viability of osteoclast precursor RAW 264.7 cells was not affected by AGP treatment at a concentration of 0.4 to 10 µM. Additionally, the number of TRAP-positive osteoclasts was significantly reduced by the same concentrations of AGP treatment. AGP also inhibited RANKL-induced NF-kappaB activation in a dose-dependent fashion as evidenced by luciferase reporter assays. In summary, this study demonstrates that AGP inhibits osteoclastogenesis in RAW 264.7 murine macrophage cells through downregulation of the NF-kappaB signaling pathway.

Clinical significance of serum survivin in patients with pancreatic ductal adenocarcinoma.

OBJECTIVE: We investigate the clinical significance of survivin levels in pancreatic ductal adenocarcinoma (PDAC) patients. PATIENTS AND METHODS: The serum level of survivin from patients with PDAC (n = 80) and age-matched healthy volunteers (n = 80) were analyzed by enzyme-linked immunosorbent assays (ELISA) prior to surgical resection. Expression levels were correlated with clinicopathological parameters. RESULTS: Serum survivin concentrations were significantly elevated in PDAC patients when compared to healthy sera (p = 0.001). High serum survivin levels were significantly associated with perineural invasion, venous invasion, lymph node status (N stage), histologic grade and T stage, but not with the tumor size, age, gender of the patients or tumor location. The median overall survival of the normal serum survivin group was longer than that of the elevated serum survivin group. The independent factors associated with overall survival were advanced pancreatic cancer and elevated serum survivin level. CONCLUSIONS: Patients with elevated serum survivin level at diagnosis demonstrated poor overall survival. Pretreatment survivin level may predict the prognosis of patients with PDAC.

A quantitative study of monochromatic X-ray transmission through zinc wires.

X-ray transmission through zinc wires of various diameters has been investigated systematically at different beam energies and sample-to-detector distances at the Shanghai Synchrotron Radiation Facility. This analysis shows that the experimentally measured transmission differs significantly from the theoretical estimation unless an appropriate point-spread function/line-spread function (PSF/LSF) is incorporated in the analysis. A number of other possible factors which may contribute to the observed inconsistencies were also assessed and these factors included higher harmonics and fluorescence; however, it was determined that these were not the dominant contributors underlying the inconsistencies. The investigation has demonstrated that the PSF/LSF is a major factor for consideration in quantitative X-ray micro-computed tomography.

Comparisons of clinical features of HLA-DRB1*07 positive and negative vitiligo patients in Chinese Han population.

BACKGROUND: Human leucocyte antigen (HLA)-II alleles have been found to be associated with vitiligo in different populations, and several studies also suggested that HLA class II alleles/haplotypes were associated with a different type vitiligo. Of HLA class II alleles, DRB1*07 has consistently shown a positive association with vitiligo in Chinese Han population. OBJECTIVE: To further explore the relationship between DRB1*07 and vitiligo and to evaluate the DRB1*07 effect on the clinical features of vitiligo in Chinese Han population. METHODS: This study investigated DRB1*07 allele distribution in 1178 unrelated Chinese vitiligo patients and 1743 healthy controls using polymerase chain reaction/sequence specific primer method and observed clinical differences between DRB1*07 positive and DRB1*07 negative patients. RESULTS: The analysis of the 1178 cases and 1743 controls revealed a highly association between DRB1*07 allele and vitiligo [odds ratio (OR) = 1.97, P = 2.13 × 10(-17) ]. DRB1*07 positive patients had early disease onset (OR = 1.49, P = 0.001), higher frequency of family history (OR = 1.44, P = 0.006) compared with DRB1*07 negative patients. CONCLUSIONS: The DRB1*07 showed significant association with vitiligo in the study population. This study confirmed that DRB1*07 positive patients had some obvious clinical differences from DRB1*07 negative patients in the Chinese Han population.

Follow-up analysis of 180 Chinese Han families: identification of a novel locus for psoriasis at 2p22.3-11.2.

BACKGROUND: Psoriasis is a common inflammatory and hyperproliferative skin disease. The pathogenesis of psoriasis remains obscure. Family and twin studies have suggested a strong genetic susceptibility to psoriasis. Eight linkage loci (PSORS1-7, PSORS9) were identified and accepted by the OMIM and an additional 16 susceptibility loci have been suggested so far. OBJECTIVES: To investigate further three suggested psoriasis susceptibility loci at 2p22.3-11.2, 13q21-32 and 17q22-25.3 in a Chinese population. Using an expanded sample of 180 Chinese families with psoriasis and improved marker coverage, we verified whether they were Chinese Han psoriasis susceptibility loci. METHODS: In total, 180 Chinese Han families with psoriasis vulgaris (including the 61 families used in the original genome-wide scan and 119 new families) were recruited from the Dermatology Department at the First Hospital Affiliated to Anhui Medical University. Two-point and multipoint parametric and nonparametric linkage (NPL) analyses were performed at 2p, 13q and 17q in the total 180 families as well as the 61 original and 119 new families separately. RESULTS: At the region 2p, a maximum multipoint NPL score of 4.11 was identified at locus D2S337 (P=0.000003), and a maximum multipoint heterogeneity LOD (HLOD) score of 4.93 (alpha=54%) was identified at the same locus in the analysis of the 180 families. However, the analysis of the 180 families did not identify any significant linkage evidence at the region 13q21-32 [a maximum multipoint HLOD score of 0.10 (alpha=7%) and NPL score of 0.95 (P=0.14)] or the region 17q22-25.3 [a maximum multipoint HLOD score of 0.08 (alpha=6%) and NPL value of 0.94 (P=0.14)]. For these two regions, the LOD scores from the 180 families as well as the 119 new families were much smaller than the ones obtained from the original 61 families. CONCLUSIONS: Our study indicates that 2p22.3-11.2 is a novel psoriasis susceptibility locus in the Chinese Han population and confirms that psoriasis is a genetically heterogeneous disease.

The familial risk of acne vulgaris in Chinese Hans - a case-control study.

BACKGROUND: Acne is a chronic inflammatory disease of the pilosebaceous follicles. Recent studies bring us increasing evidences that hereditary factors play an important but indirect role in acne. OBJECTIVE: To investigate the possible role of genetic factors in the pathogenesis of acne vulgaris in Chinese Han ethnic group. PATIENTS AND METHODS: Volunteers of 975 acne cases and 580 controls were included, contributing 3009 and 1825 first-degree relatives, respectively. One thousand and eighty-five first-degree relatives of acne cases were affected with facial acne. This compared with 223 first-degree relatives of non-acne controls. The odds ratio was used to estimate the relative risk for acne vulgaris associated with having an affected first-degree relative. RESULTS: The risk of acne vulgaris occurring in a relative of a patient with acne vulgaris was significantly greater than for the relative of an unaffected individual (odds ratio 4.05, 95% confidence interval (CI): 3.45-4.76, P<0.001). CONCLUSION: Our study suggests that familial factors are important in determining individual susceptibility to acne vulgaris.

A novel missense mutation L468Q of keratin 6a in pachyonychia congenita type 1.

BACKGROUND: Pachyonychia congenita is an autosomal dominant disorder that usually develops in early infancy. The major features of the syndrome are hypertrophic nail dystrophy, palmoplantar keratoderma and oral leucokeratosis, accompanied by other ectodermal defects, according to subtype. OBJECTIVE: To analyse the K6a gene mutation in a sporadic Chinese patient with pachyonychia congenita type 1 (PC-1) and to explore the relationship between the genotype and phenotype of PC-1. METHODS: Genomic DNA was extracted from peripheral blood of the patient with PC-1 and 100 unrelated controls. The whole coding region of K6a gene was amplified using long-range polymerase chain reaction (PCR); nested PCR was then used to amplify the mutation 'hot-spot' of the K6a gene. The PCR products were directly sequenced to detect the mutation. RESULTS: A novel missense mutation L468Q in the helix 2B domain of the K6a polypeptide was identified in the patient but not in the healthy individuals from the family and 100 unrelated control individuals. CONCLUSIONS: We describe this mutation for the first time, and provide further evidence that the helix boundary motif sequences of K6a are a mutation 'hot-spot'.