Detection of a new mutation (1343-TT) in the iduronate-2-sulfatase gene from a Chinese patient with mucopolysaccharidosis type II / 中华儿科杂志

<p><b>OBJECTIVE</b>Mutations of the iduronate-2-sulfatase (IDS) gene is the ultimate cause of Hunter syndrome. Clarification of the nature of mutations will create a necessary premise for prenatal gene diagnosis. A mucopolysaccharidosis (MPS) type II patient and his parents from an ethnic minority in Yunnan province were studied to identify their possible mutation in IDS gene to establish the basis for prenatal gene diagnosis.</p><p><b>METHODS</b>The patient was a boy, 6 years and 10 months old. Urine glycosaminoglycans (GAGs) assay was used for preliminary diagnosis of the patient and his parents with the disease. The three related persons' DNA was extracted and the concentration and purity of the DNA were measured after the urine test results confirmed the diagnosis. Polymerase chain reaction-denaturing high performance liquid chromatography (PCR-DHPLC) analysis was performed to detect the position of the mutation around the hot spots of mutation in exon 9, 3, 8 of the IDS gene. DNA bidirectional direct sequencing was applied to analyze the mutation detected by PCR-DHPLC.</p><p><b>RESULTS</b>The results of GAGs test showed that in the child with MPS, dermatan sulfate (DS) was positive (+++), heparan sulfate (HS) (+++), chondroitin sulfate (CS) and keratan sulfate (KS) were negative (-); while in his parents none of DS, HS, CS and KS was positive. Abnormal peaks in exon 9 of IDS gene shown by PCR-DHPLC were found in the patient. His mother had heterozygotic peaks. A new frame-mutation (1343-TT) in exon 9 of IDS gene of this patient was confirmed by DNA sequencing. The position where mutation occurred was inside codon 407 (TTT), that means two "T" deleted at position 1343 base pair (1343-TT) in cDNA of the IDS gene, caused a new frame-mutation. It caused elongation of the amino acid chain to a terminal codon TGA at position 429. Thus the peptide chain was shortened from 550 to 428 amino acids. The patient is a hemizygote of the mutation and his mother is a heterozygote.</p><p><b>CONCLUSION</b>A new frame-mutation (1343-TT) on the IDS gene was identified in this study. The patient is a hemizygote and his mother is a heterozygote. The mutation (1343-TT) resulted in loss of 122 amino acids, which probably caused seriously decreased enzyme activity of IDS, and the authors speculate that this mutation may be the pathological basis of the disease. So, if the mother becomes pregnant again, a prenatal gene diagnostic test for the same mutation should be performed. Furthermore, PCR-DHPLC followed by DNA sequencing are effective methods for diagnosis, including prenatal diagnosis of MPS II.</p>

A new mutation of iduronate-2-sulfatase gene from the patient with Hunter syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the mutations of iduronate-2-sulfatase (IDS) gene, and to establish a basis of prenatal gene diagnosis of Hunter syndrome.</p><p><b>METHODS</b>Urine glycosaminoglycan (GAG) assay was used to preliminary diagnosis of mucopolysaccharidosis. PCR-denaturing high-performance liquidchromatograptly (PCR-DHPLC) analysis was performed to detect the mutation in exons 9, 3, 8 of the IDS gene. DNA sequencing was applied to analyze the mutation detected by PCR-DHPLC.</p><p><b>RESULTS</b>Abnormal peaks were found by PCR-DHPLC. A new frame-mutation (1569+TT) in exon 9 of IDS gene was identified by DNA sequencing. Two "T"q inserted in position 1569 base pair (1569+TT) caused a substitution of codon 482 (TTA, leucine) to 482 (TTT, phenylalanine). The "TT" insertion results in the decrease of amino acids from 550 to 482. The patient is a hemizygote and his mother is a heterozygote.</p><p><b>CONCLUSION</b>A new frame-shift mutation of IDS gene is found to report. The mutation (1569+TT) results in 68 amino acids lost. Probably it causes the enzyme activity seriously dropped down and being pathologically the basis of disease.</p>

Denaturing high-performance liquid chromatography technique platform applied to screen G6PD deficient variants / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Of denaturing high performance liquid chromatography (DHPLC), a technique platform was developed for screening G6PD deficient variants.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Identification of G6PD gene variants from Hakka population in Guangdong province / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Studying on G6PD polymorphism from Hakka population in Guangdong province.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Complex mutations of 1311 C-->T in exon 11 and 93 T-->C in intron 11 in G6PD gene / 中华血液学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>Abnormal band in exon 11 was found in 12 cases. DNA sequencing showed that they were 1311 mutation together with 93 mutation.</p><p><b>CONCLUSION</b>This complex mutation may be the cause of reduced activity of G6PD enzyme.</p>

Study on gene mutations of alpha-thalassemia in the South of China / 中国实验血液学杂志

There is a high prevalence of thalassemia in the South of China. To explore the genotype of alpha-thalassemia as well as the distribution of alpha globin gene mutation in the South of China, 356 patients with heterozygote alpha(+) thalassemia, heterozygote alpha(0) or homozygote alpha(+) thalassemia and 78 patients with HbH were analyzed. The gene diagnosis methods including Gap-PCR, nested-PCR, PCR-RE, PCR-SSCP, 4P-ASPCR and DNA sequence analysis were used. The results showed that among 356 patients, 295 patients with --SEA/alphaalpha (82.87%), 1 patient with alphaalpha/alpha-alpha(3.7) (0.28%), 3 patients with alphaalpha/alpha-alpha(4.2) (0.84%), 3 patients with alphaalpha/alpha(CS)alpha (0.84%), 1 patient with alphaalpha/alphaalpha(QS) (0.28%) and 2 patients with alphaalpha/alpha(Westmead) alpha (0.56%) were found. The homozygote with -alpha(4.2) or -alpha(3.7) was not found. In 78 patients with HbH, 29 patients with --SEA/alphaalpha(-3.7) (37.2%), 20 patients with --SEA/alphaalpha(-4.2) (25.6%), 19 patients with --SEA/alphaalpha(CS) (24.3%), 2 patients with --SEA/alphaalpha(QS) (2.6%) were detected, and other remaiming 8 patients were needed to be defined. Among the non-defined 8 patients, the synonymous mutation with C-->G transversion (GCC-GCG) at codon 65 in the exon 2 of alpha 2-globin gene was detected in 2 unrelated HbH patients came from Guangxi province. Whether it correlated with the phenotype of HbH disease or it is only a single nucleotide polymorphism site (SNPs), should be confirmed in the future. In addition, a set of gene diagnosis methods based on PCR to screen deletion and non-deletion genotypes of alpha-thalassemia in Chinese was improved. A new method, 4P-ASPCR, to detect Hb CS and Hb QS was also developed. The method was verified to be more accurate, time-saving and economic. In conclusion, the genotypes of alpha-thalassemia in Chinese are very complicated, the genotypes of alpha-thalassemia in Chinese need to be further studied, the results of this research probably have practical significance for the gene diagnosis or antenatal diagnosis of alpha-thalassemia in the South of China.