G6PD genotype and its associated enzymatic activity in a Chinese population.

Knowledge of the G6PD genotype and its associated enzyme activity is significant for population genetics, diagnosis of disease, and management of patients. We tested 2,872 unrelated subjects from a Hakka population in China for G6PD activity by the WHO standard method and for genotype by DHPLC and DNA sequencing. Among female heterozygotes, 78.5% had relatively normal enzyme activity. The phenotype frequency of G6PD deficiency is 0.028, and the causal allele frequency is 0.060 in females. The accuracy, sensitivity, and specificity of DHPLC are more than 98% for detecting G6PD-deficient hemizygotes, heterozygotes, and homozygotes. Measuring enzyme activity alone is not sufficient for the diagnosis of heterozygotes. A combination of enzyme activity and DNA analysis should be used.

[Rapid prenatal genetic diagnosis of a fetus with a high risk for Morquio A syndrome].

OBJECTIVE: To provide rapid and accurate prenatal genetic diagnosis for a fetus with high risk of Morquio A syndrome. METHODS: Based on ascertained etiology of the proband and genotypes of the parents, particular mutations of the GALNS gene were screened at 10th gestational week with amplification refractory mutation system (ARMS), denaturing high performance liquid chromatography (DHPLC), and direct DNA sequencing. RESULTS: DHPLC screening has identified abnormal double peaks in the PCR products of exons 1 and 10, whilst only a single peak was detected in normal controls. Amplification of ARMS specific primers derived a specific product for the fetus's gene, whilst no similar product was detected in normal controls. Sequencing of PCR products confirmed that exons 1 and 10 of the GALNS gene from the fetus contained a heterozygous paternal c.106-111 del (p.L36-L37 del) deletion and a heterozygous maternal c.1097 T>C (p.L366P) missense mutation, which resulted in a compound heterozygote status. CONCLUSION: The fetus was diagnosed with Morquio A syndrome and a genotype similar to the proband. Termination of the pregnancy was recommended. Combined ARMS, DHPLC and DNA sequencing are effective for rapid and accurate prenatal diagnosis for fetus with a high risk for Morquio A syndrome. Such methods are particularly suitable for early diagnosis when pathogenesis is clear. Furthermore, combined ARMS and DHPLC are suitable for rapid processing of large numbers of samples for the identification of new mutations.

[Identification of a novel pathogenic mutation in MATP gene with oculocutaneous albinism type IV from a consanguineous marriage family].

OBJECTIVE: To clarify the pathogenicity-related genes and its mutations in an oculocutaneous albinism (OCA) patient from a consanguineous marriage family. METHODS: Polymerase chain reaction (PCR) and automatic DNA sequencing methods, chromosome walking by PCR amplification techniques (PCR-Walking), multiplex PCR in a single PCR tube with 3 primers bridging the breakpoint (Gap-PCR) and bioinformatic analysis were employed for screening the mutations and identifying the novel mutation in the patient and his family. RESULTS: A pathogenic deletion of 6365 bp was found in MATP gene with a range of c.562-1118 (± 2) to c.885 + 4923 (± 2). The patient was homozygous for deletion mutation. CONCLUSION: A large deletion mutation was first detected and identified in OCA4.

[Prenatal diagnosis of oculocutaneous albinism type IV and discovery of a novel mutation].

OBJECTIVE: To provide guidance for clinical genetic counseling and prenatal diagnosis of oculocutaneous albinism (OCA) in China. METHODS: PCR and automatic DNA sequencing were applied to obtain the genotypes of the patients and their parents in three Chinese albinism families. Prenatal gene diagnoses were performed at early pregnancy by chorionic villus sampling (CVS) or by amniocentesis at mid-pregnancy. RESULTS: The three patients were all OCA4, whose genotypes were G349R/c.870delC, G349R/P419L and G349R/D160H, respectively. The three couples had been diagnosed as carriers. In family 1, the first fetus was diagnosed as affected. Termination of pregnancy was opted following genetic counseling. The second fetus (monozygotic twin) was heterozygous only with the paternal G349R mutation. The fetus in family 2 did not get either one of the two mutations. The fetus in family 3 was heterozygous only with the paternal G349R mutation. CONCLUSION: This study detected three reported pathogenic mutations of the membrane associated transporter protein gene (MATP), including G349R, D160H and P419L, and identified a novel pathogenic mutation c.870delC. The prenatal gene diagnosis of OCA4 will be important to prevent the birth of affected child.

The protective effect of obeticholic acid on lipopolysaccharide-induced disorder of maternal bile acid metabolism in pregnant mice.

The disorder of bile acid metabolism is a common feature during pregnancy, which leads to adverse birth outcomes and maternal damage effects. However, the cause and therapy about the disorder of bile acid metabolism are still poor. Microbial infection often occurs in pregnant women, which can induce the disorder of bile acid metabolism in adult mice. Here, this study observed the acute effect of lipopolysaccharide (LPS) on maternal bile acid of pregnant mice at gestational day 17 and the protective effect of obeticholic acid (OCA) pretreatment, a potent agonist of bile acid receptor farnesoid X receptor (FXR). The results showed LPS significantly increased the level of maternal serum and disordered bile acids components of maternal serum and liver, which were ameliorated by OCA pretreatment with obviously reducing the contents of CA, TCA, DCA, TCDCA, CDCA, GCA and TDCA in maternal serum and DCA, TCA, TDCA, TUDCA, CDCA and TCDCA in maternal liver. Furthermore, we investigated the effects of OCA on LPS-disrupted bile acid metabolism in maternal liver. LPS disrupted maternal bile acid profile by decreasing transport and metabolism with hepatic tight junctions of bile acid in pregnant mice. OCA obviously increased the protein level of nuclear FXR and regulated its target genes involving in the metabolism of bile acid, which was characterized by the lower expression of bile acid synthase CYP7A1, the higher expression of CYP3A and the higher mRNA level of transporter Mdr1a/b. This study provided the evidences that LPS disrupted bile acid metabolism in the late stage of pregnant mice and OCA pretreatment played the protective role on it by activating FXR.

[Prenatal diagnosis of oculocutaneous albinism type II and discovery of two novel mutations].

OBJECTIVE: To investigate the genotype of oculocutaneous albinism type II (OCA2) and perform prenatal gene diagnosis for OCA2. METHODS: Peripheral blood samples were collected from a 9-year-old girl with OCA and her parents, the mother being pregnant. PCR, automatic sequence analysis and denaturing high performance liquid chromatography (DHPLC) were used to analyze the TYR gene and P gene so as to screen the OCA genes. Amniocentesis was conducted when the mother was 20-week pregnant and the amniotic cells underwent screening of the 2 specific mutations. Peripheral blood samples were collected from 100 healthy persons without phenotype of OCA to undergo genetic analysis. RESULTS: The TYR gene of the proband did not show any mutation, and 2 new mutations were found in her P gene: p. N476D (c. 1426 A>G) and p.Y827H (c.2479T>C). Her father and mother were heterozygote of Y827H and N476D respectively. Based on these findings the amniotic cells underwent sequencing of enlarged fragments of the exons 14 and 24 containing the mutation sites. The result showed that the fetus only got the maternal N476D mutation and didn't get the paternal Y827H mutation. So the fetus was predicted to be a carrier of OCA2 with normal appearance. The baby was born normal later as predicted. None of these 2 mutations was found in the 100 healthy persons. CONCLUSION: This is a success of prenatal gene diagnosis of OCA2. Two novel mutations of the P gene related to OCA have been discovered.

Prenatal molecular diagnosis of Duchenne and Becker muscular dystrophy.

OBJECTIVE: Duchenne and Becker muscular dystrophy (DMD/BMD) is an X-linked lethal recessive disease caused by mutations in the dystrophy gene. There is no efficient treatment for this serious and disabling disease. We established a combination method to detect carriers and perform prenatal diagnosis. METHODS: In our study, from 1994 to 2005, using a different combination of 5 methods, including SRY gene amplification, multiplex PCR, multiplex Fluorescence PCR capillary electrophoresis, multiplex ligation-dependent probe amplification (MLPA) and linkage analysis of short tandem repeats (STR), 36 prenatal diagnosis were performed for pregnancies at risk of having a DMD/BMD baby through amniocentesis. RESULTS: Fourteen out of 21 male fetuses were found to be affected and respective pregnancies were terminated. A combined diagnostic rate of 83% was achieved for 30 cases with deletions, duplications, and non-deletion mutations after tested by more than one method. CONCLUSION: Using a combined method, we can diagnoses patients and carriers in DMD families, and perform prenatal diagnosis for the risk fetus. MLPA provides a simple, rapid and accurate method for deletions and duplications of all the 79 DMD exons. MLPA method for DMD diagnosis is the first report in our country.

Denaturing high-performance liquid chromatography technique platform applied to screen G6PD deficient variants.

OBJECTIVE: Of denaturing high performance liquid chromatography (DHPLC), a technique platform was developed for screening G6PD deficient variants. METHODS: When applied to screen and identify the G6PD deficient variants from 124 patients who come from 11 nations in China, the DHPLC was compared with amplification refractory mutation system (ARMS) or DNA sequence technique and assessed carefully in its accuracy, sensitivity, efficiency and the cost of experiment. RESULTS: The G6PD-deficient variants, such as 1388 G-->A (36/124 cases), 1376 G-->T(35), 95 A-->G (14), 1024 C-->T (3), 392 G-->T (4), 871 G-->A /1311 C-->T /IVS XI +93 t-->c (9), 871 G-->A (1), 1311 C-->T/IVS XI +93 t-->c (4), 1376 G-->T /1388 G-->A (1) and so on, were characterized as sharp peaks by DHPLC and verified by DNA sequence. Further, the standard chromatograms were put into database for 8 kinds of common G6PD deficient variants in Chinese populations. And also DHPLC found 3 G6PD variants (1388 G-->A) from 103 negative controls. With taking 8.8 minutes and costing 1 dollar for each sample, DHPLC successfully detected and identified 34 heterozygous females from patients with G6PD deficiency. However, ARMS checked 83 positive controls but got 12 false G6PD mutants, of which 5 were false positive, 7 false negative. Above results show that DHPLC sounds like to be more convenience, sensitive and accurate than ARMS and DNA sequence techniques for checking G6PD mutants. CONCLUSION: DHPLC is of great advantage to screen the G6PD deficient variants with accuracy, convenience, automation and less cost, and significantly to identify the female heterozygote and clinical type IV individuals with G6PD deficiency.

[Identification of G6PD gene variants from Hakka population in Guangdong province].

OBJECTIVE: Studying on G6PD polymorphism from Hakka population in Guangdong province. METHODS: Identifying the variants of G6PD gene and determining the frequencies respectively with the use of amplified refractory mutation system(ARMS), polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) and ABI 3100 DNA sequencing technologies. RESULTS: Mutations of G6PD gene in cDNA 1388 (G-->A), 1376 (G-->T), 95 (A-->G), 392 (G-->T), 1024 (C-->T), 1311 (C-->T) have been found. CONCLUSION: G6PD cDNA 1388 (G-->A), 1376 (G-->T), 95(A--> G), 392 (G-->T), 1024 (C-->T) and 1311 (C-->T) accompanied with intron 11 (93 T-->C) are the common mutations in Chinese population. cDNA 1388 (G-->A), cDNA 1376 (G-->T) are the most popular G6PD gene variants in Hakka population. In this study, no new type of G6PD gene mutation was found in the Hakkas of Guangdong.

[Fâ ¨ gene all exons sequencing technology in hemophilia B gene carriers detection and the application of prenatal gene diagnosis].

OBJECTIVE: To establish a feasible protocol to provide genetic diagnosis and prenatal diagnosis in Chinese hemophilia patients and their relatives by direct exon sequencing. METHODS: In our study, genetic diagnosis was performed on 5 unrelated families with informed consent, which included 3 pregnant women who asked for prenatal diagnosis. Umbilical cord blood was obtained from 2 fetuses and amniotic fluid from another fetus. After extraction of the genomic DNA, all of the exons, exon-intron boundaries and their flanks of FⅨ gene were amplified by polymerase chain reaction (PCR). PCR products were detected through direct-sequencing. RESULTS: Sequence analysis indicated that the patients and carriers from 5 families have the pathogenic mutations,c.1022G>A (p.R341Q), c.484 C>T (p. R162X), c.1135C>T (p.R379X), c.799C>T (p.H267Y), c.1232G＞T (p.S411I), respectively. Except c.484 C>T (p. R162X), 4 of the 5 mutations were reported firstly in Chinese population. During prenatal diagnosis, one of the fetuses was found to be affected with c.484C>T; p.R162X. The remaining two fetuses were diagnosed as normal, the results of which were later verified by post-birth diagnosis, and factor FⅨ activities in plasma was 52.7% and 76.2%, respectively. CONCLUSION: In the quest of strict quality control, exon sequence on FⅨ gene was a rapid and accurate method for genetic diagnosis and prenatal diagnosis of hemophilia B.

A novel Norrie disease pseudoglioma gene mutation, c.-1_2delAAT, responsible for Norrie disease in a Chinese family.

AIM: To investigate the genetic findings and phenotypic characteristics of a Chinese family with Norrie disease (ND). METHODS: Molecular genetic analysis and clinical examinations were performed on a Chinese family with ND. Mutations in the Norrie disease pseudoglioma (NDP) gene were detected by direct sequencing. Haplotypes were constructed and compared with the phenotypes in the family. Evolutionary comparisons and mutant open reading frame (ORF) prediction were also undertaken. RESULTS: Two family members with ocular manifestations were diagnosed with ND. No signs of sensorineural hearing loss were observed in either patient, while one of them showed signs of mild mental retardation. A novel heterozygous mutation in the NDP gene, c.-1_2delAAT, was detected in both patients. The mutation and the mutation bearing haplotype co-segregated with the ND phenotype in males and was transmitted from their mothers and/or grandmothers (II:2). The male without ND did not harbor the mutation. The mutation occurred at the highly conserved nucleotides. ORF finder predicted that the mutation would lead to the production of a truncated protein that lacks the first 11 N-terminal amino acids. CONCLUSION: A novel mutation, c.-1_2delAAT in the NDP gene, was identified in a Chinese family with ND. This mutation caused ND without obvious sensorineural hearing loss. Mental disorder was found in one but not the other patients. The clinical heterogeneity in the family indicated that other genetic variants and epigenetic factors may also play a role in the disease presentation.

[Genotype of thalassemia genes and the polymorphism of ß- globin gene in Cantonese].

OBJECTIVE: To understand the genotype of α and ß-globin, as well as the polymorphism of ß-globin gene in Cantonese in recent years, and to provide an effective genetic diagnosis for thalassemia (thal). METHODS: The single-tube complex PCR was used to detect 3 types of deletional α-thal, reverse dot blotting (RDB)/PCR to detect 3 kinds of undeletional α-thal-αCS, αQS, αWSand 18 kinds of ß-thal mutations which were common in Chinese population. A total of 454 cases from Guangdong were undergone thal genotype genetic diagnosis. Among the 454 cases, 142 cases were selected to perform the single nucleotide polymorphisms (SNPs) analysis of ß- globin gene by denaturing high-performance liquid chromatography (DHPLC)combining the whole gene sequencing. RESULTS: Of the 454 cases, 438 were diagnosed as thalassemia, including 246 of α-thal, 164 of ß-thal and 28 of αß-thal. In 246 α-thal cases, deletions were the dominant mutations, including 197 cases of αα/--(SEA), 20 of αα/-α(3.7) and 9 of αα/-α(4.2). In 164 ß- thal cases, heterozygotes accounted for 92.7% (152/164), the main genotypes were CD41- 42, IVS-II-654, ï¹£28 and CD17, and the dual heterozygotes and homozygotes accounted for 4.9% (8/164) and 2.4% (4/164), respectively. The result of ß-globin gene screening by DHPLC combining with sequencing was consistent with that of RDB. Moreover, we also found 9 kinds of SNP, in which 2 were unreported, the IVS-I-13 G> A and IVS-II- 310 T>C. In the tested samples, the frequency of 4 kinds SNP was high, among which 3 kinds SNPs-rs713040, rs10768683 and rs1609812 were carried together. CONCLUSION: The dominant genotypes were αα/--(SEA) in α-thal cases, CD41-42, IVS-II-654, -28 and CD17 in ß-thal. The frequency of ß-thal heterozygotes, homozygotes and αß-thal is high. DHPLC combining the whole ß-globin gene sequencing can effectively detect the common ß-thal mutation and even new mutations or SNPs. In Cantonese, the frequency of SNP rs713040, rs10768683, rs7480526 and rs1609812 of ß-globin gene was high, and there may exist genetic linkage between rs713040, rs10768683 and rs1609812.

Oculocutaneous albinism type 3 (OCA3): analysis of two novel mutations in TYRP1 gene in two Chinese patients.

Oculocutaneous albinism (OCA) is a genetic disease characterized by the reduction or deficiency of melanin in eyes, skin, and hair. OCA exhibits genetic heterogeneity. Presently, there are four types of OCA named as OCA1, OCA2, OCA3, and OCA4. OCA3 is more common in African born blacks but rarely found in other ethnic populations. Our recent genotyping of patients with OCA of Chinese descent has identified two patients who were not OCA1, OCA2, or OCA4. Examination and analysis of the TYRP1 gene identified them to be having OCA3. PCR and DNA sequencing analysis found that the mutant TYPR1 alleles were present in each of the two patients, c.780-791del/c.1067G>A (p.R356Q) and c.625G>TT (p.G209LfsX1)/c.643C>T (p.H215Y). The c.780-791del and c.1067G>A mutations have been already reported. However, the c.625G>TT and c.643C>T mutations have not been previously reported and were found to be maternal and paternal mutations, respectively. Moreover, population screening and bioinformatic analysis were carried out to determine the effects of these two mutations which revealed that both the mutation were pathogenic. Based on the similar mild phenotype of these two patients, we suggest that OCA3 might be prevalent within the Chinese population.

[Improvement of I-PCR and its application in gene diagnosis of hemophilia A].

OBJECTIVE: To improve inversion-polymerase chain reaction (I-PCR) in detection of factor VIII (FVIII) intron 22 inversion for gene diagnosis and prenatal diagnosis of hemophilia A (HA). METHODS: The modified I-PCR was applied to detect FVIII intron 22 inversion in 8 families with HA. The prenatal diagnosis was performed for 2 pregnant women in the families. The fetal blood samples were obtained by cordocentesis at 22 and 26 weeks gestation respectively. RESULTS: Four of 8 HA families were diagnosed to be FVIII intron 22 inversion. Two fetuses were identified to be normal and one of them was born normal. CONCLUSION: The modified I-PCR enables the gene diagnosis and prenatal diagnosis of FVIII intron 22 inversion more accurately and rapidly.

[Aerobic microbial degradation of polybrominated diphenyl ethers].

The biodegradation of 4, 4'-dibromodipheny ether (BDE15) and decabromodiphenyl ether (BDE209) by white rot fungi under aerobic conditions was studied. Effects of non-ionic surfactant Tween 80 and beta-cyclodextrin as solubilizers on the apparent solubilities and biodegradation rates of BDE15 and BDE209 were also evaluated. The results showed that both BDE15 and BDE209 were efficiently degraded by white rot fungi. The degradation rates were 43.0% and 62.5% for BDE209 and BDE15, respectively, after 10 d incubation. The degradation of BDE209 was greatly enhanced by addition of Tween 80 (< or = 700 mg/L) and beta-cyclodextrin, which may own to their solubilization effects on BDE209. However, Tween 80 at a high concentration (900 mg/L) would restrain the fungal growth, thereby decrease the degradation of BDE209. Addition of Tween 80 and beta-cyclodextrin exhibited some negative effects on the degradation of BDE15, which may due to decreased concentration of free BDE15 in water solution resulted from inclusion function of Tween 80 micelles and beta-cyclodextrin cavity, although the apparent solubility of BDE15 was drastically increased by both of them.

[Complex mutations of 1311 C-->T in exon 11 and 93 T-->C in intron 11 in G6PD gene].

OBJECTIVE: To investigate the relationship between complex 1311 mutation of C-->T in exon 11 and 93 T-->C in intron 11 of G6PD gene and the G6PD deficiency. METHODS: Using NBT paper strip method to screen and quantitative NBT method to confirm G6PD deficiency. PCR-SSCP technique was used to find the abnormal exon 11 and the amplification refractory mutation system (ARMS) to identify 1311 mutation, and DNA sequencing to identify the complex mutation at 1311 in exon 11 and 93 in intron 11. RESULTS: Abnormal band in exon 11 was found in 12 cases. DNA sequencing showed that they were 1311 mutation together with 93 mutation. CONCLUSION: This complex mutation may be the cause of reduced activity of G6PD enzyme.