[Analysis of small supernumerary marker chromosome 15q11 in four infertile males].

OBJECTIVE: To delineate the origins of small supernumerary marker chromosomes (sSMCs) identified in 4 infertile males. METHODS: The sSMCs were analyzed with combined G-banding, N-banding, multiplex ligation-dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH) and single nucleotide polymorphisms array (SNP-array) techniques. RESULTS: G-banding analysis has suggested a 46,X,-Y,+mar karyotype in all of the 4 cases. N-banding revealed that all of the sSMCs have possessed two satellites located on both sides. By MLPA, 1 patient showed copy number gains for 15q11.2 region. SNP-array analysis suggested that all had duplication for 15q11.1-q11.2 region, spanning 3.06 Mb, 0.9118 Mb, 1.728 Mb and 0.287 Mb, respectively. By FISH analysis, all of the sSMCs showed two hybridization signals, indicating that they were dicentric chromosomes. CONCLUSION: In all of the four cases, the marker chromosomes have derived from chromosome 15 and were bisatellited and dicentric, which gave rise to a karyotype of 47,XY,+ish,inv dup(15)(q11)(D15Z4++). sSMC 15q11 therefore may be a major cause for male infertility.

[Delineation of three structural Y chromosome aberrations combined molecular techniques].

OBJECTIVE: To delineate the structure of Y chromosome aberrations and recombinant mechanisms for three patients. METHODS: Karyotype analysis, multiplex ligation dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH), Y chromosome sequence tagged sites (STS) analysis, human whole genome-wide SNP array were used. RESULTS: The karyotypes of the three patients were 46, X, +mar. As suggested by MLPA analysis, case 1 has increased copy numbers of SRY, ZFY and UTY genes, case 2 had increased copies of SRY and ZFY genes, and deletion of UTY gene, and case 3 had decreased copies for subtelomeric regions of X/Yp and X/Yq. By STSs analysis, case 1 has retained SRY, sY84 and sY86 in the AZFa region, sY1227 in the AZFb region, whilst lost sY1228 in the AZFb region and other STSs in the AZFc region. Its breakpoint was thereby mapped between sY1227 and sY1228. Case 2 has retained SRY and sY1200 in the centromeric region, whilst has deletion of other STSs. Case 3 has retained SRY and STSs in the AZF regions. By SNP array, case 1 had duplicated Yp11.31-p11.2 and deletion of Yq11.22-q11.23 (approximately 5.18 Mb). Case 2 had duplicated Yp11.31-p11.2 and deletion of Yq11.21-q11.23 (approximately 14.644 Mb). Case 3 had single copy number deletion of p22.33 and q28 in the subtelomeric region of X/Yp and X/Yq. By FISH, cases 1 and 2 showed two signals for SRY and DYZ3 but no signal for DYZ1 on their marker chromosomes. Combining above results, the karyotypes of cases 1, 2 and 3 were determined as 46, X, idic(Y) (q11.23), 46, X, idic(Y) (q10) and 46, X, r(Y) (p11q12), respectively. CONCLUSION: Y chromosome aberrations are variable. Combined use of MLPA, STSs, FISH and SNP array is effective for revealing the breakpoints and recombinant mechanisms.

[Partial AZfc region deletions of the Y chromosome in spermatogenic dysfunction patients].

OBJECTIVE: To investigate the influence of partial deletions in the AZFc region of the Y chromosome on spermatogenesis. METHODS: We selected 9 sequence tagged sites (sY1258, sY1291, sY254, sY255, sY1201, sY1206, sY1161, sY1197 and sY1191) in the AZFc region of the Y chromosome, with ZFX/ZFY and SRY (sY14) as the interior control. We amplified by multiplex PCR the DNA of 160 patients with azoospermia or severe oligozoospermia that showed no microdeletion of the Y chromosome (the case group) and another 76 males with normal fertility (the control group). For the individuals suspected of DAZ gene deletion, we detected the single nucleotide polymorphism sites (SNPs) in the four copies of the DAZ gene by single nucleotide variation (SNV) analysis to determine the types of DAZ copy deletion. RESULTS: In the case group, there were 10 cases of gr/gr (sY1291) deletion (6.3%), 14 b2/b3 (sY1191) deletion (8.8%), 1 sY1291,sY1197 deletion (0.6%), 1 b1/b2 deletion (0.6%) and 1 b1/b3 deletion (0.6%), while in the control group, there were 4 cases of gr/gr deletion (5.3%) and 4 b2/b3 deletion (5.3%). SNV analysis showed DAZ1/DAZ2 deletion in all those with gr/gr and those with b1/b3 deletion, DAZ3/DAZ4 deletion in those with b2/b3 deletion, and DAZ-SNV sY587 deletion in 1 case of sY1291, sY1197 deletion, but no DAZ deletion was found in 1 case of b1/b2 deletion. CONCLUSION: B2/b3 (sY1191) and gr/gr (sY1291) deletions are genomic polymorphisms and quite common in the normal Chinese population; while b1/b2, b1/b3, and sY1291, sY1197 deletions may be high risk factors of dyszoospermia.

[Prenatal molecular diagnosis of four fetuses at high risk for X-linked adrenoleukodystrophy].

OBJECTIVE: To investigate methods for prenatal molecular diagnosis of fetuses at high risk for X-linked adrenoleukodystrophy (X-ALD). METHODS: The amniotic fluid was obtained and genomic DNA was isolated from amniotic fluid cells. Maternal contamination was evaluated by paternity test. PCR-RFLP, sequencing and denaturing high performance liquid chromatography (DHPLC) were used to detect the ABCD1 gene of fetal genome. RESULTS: In the pedigree 1, the PCR product (799 bp) of the fetus 1 and her father (normal control) could be digested with BcnI. No P560L mutation, which was present in the index patient, was detected in the ABCD1 gene from the genomic DNA of the fetus 1 using direct sequencing. In the pedigree 2, the PCR product (232 bp) of the fetus 2 and her father could not be digested with MaeI and no Q177X mutation, which was present in the propositus, was detected in the ABCD1 gene from the genomic DNA of the fetus 2 using direct sequencing. In the pedigree 3, the PCR product (271 bp) was digested with AciI, the pattern of the fetus 3 and the propositus being the same, and the R617C mutation was found in the ABCD1 gene from the genomic DNA of the fetus 3 using direct sequencing. In the pedigree 4, the PCR product (269 bp) was analyzed with the DHPLC, and the pattern of elution peaks of the fetus 4 and her father was similar, but different from that of the propositus. No K276E mutation was detectable in the ABCD1 gene from the genomic DNA of the fetus 4 by using direct sequencing. Judging from the sex of the fetuses, fetuses 1 and 2 were normal homozygotes, fetus 3 was an ALD hemizygote, and fetus 4 was a normal hemizygote. CONCLUSION: A new protocol for X-ALD prenatal molecular diagnosis is proposed, which would ensure the accuracy of prenatal diagnosis.

[Molecular diagnosis of spinal muscular atrophy by multiplex ligation-dependent probe amplification].

OBJECTIVE: To investigate the effect of multiplex ligation-dependent probe amplification (MLPA) in molecular diagnosis of spinal muscular atrophy (SMA). METHODS: Peripheral blood samples were collected from 13 SMA patients, 31 parents of SMA patients, 50 healthy individuals without family history of SMA, and 10 specimens of amniotic fluid from these families were collected too. Genomic DNA was analyzed by MLPA, conventional PCR-RFLP, and allele-specific PCR. RESULTS: In complete agreement with the results of conventional PCR-RFLP and allele-specific PCR, MLPA analysis showed that all of the 13 patients had homozygous deletion of the survival of motor neuron 1 (SMN1) gene, and there was significant difference between the SMA severity (type I to type III) and SMN2 copy number (P < 0.05). Of the 31 parents 29 (93.5%) had 1 copy of SMN1, 2 (6.5%) had 2 copies of SMN1. Of the 50 healthy individuals, 1 (2.0%) had 1 copy of SMN1, 48 (96.0%) had 2 copies of SMN1, and 1 (2.0%) had 3 copies. The SMN1 copy number of the parents was significantly higher than that of the healthy individuals (P < 0.01). Two of the 10 fetuses had homozygous deletion of SMN1. CONCLUSION: The MLPA technique has proved to be an accurate and reliable tool for the molecular diagnosis of SMA, both in patients and in healthy carriers.

[Prenatal diagnosis of 5 fetuses with high risk of developing spinal muscular atrophy].

OBJECTIVE: To perform prenatal diagnosis for 5 pregnant women who had given birth to children with spinal muscular atrophy (SMA). METHODS: Thirty to forty mililiters of amniotic fluid was obtained by amniocentesis under ultrasonic monitoring. DNA was extracted directly from sediment of amniotic fluid. Short tandem repeat (STR) profiling was carried out to evaluate the contamination of amniotic DNA by maternal genomic DNA. Two methods, PCR-restriction fragment length polymorphism (PCR-RFLP) and allele-specific PCR, were used to analyze exon 7 of SMN gene from amniotic DNA. RESULTS: Comparing the 16 STR sites of each fetus with those of his/her parents, there was no or little contamination of amniotic DNA by maternal genomic DNA. In conventional PCR-RFLP, part of the PCR product (189 bp) from amniotic DNA of fetus A, C, or D remained intact after digestion with Dra I, while the PCR product from amniotic DNA of fetus B or E was completely digested by Dra I. In allele-specific PCR, exon 7 of both SMN1 and SMN2 gene could be seen when amniotic DNA of fetuses A, C, or D was analyzed, while only exon 7 of SMN2 could be seen when amniotic DNA of fetuses B or E was analyzed. CONCLUSION: Homozygous deletion of SMN1 is not detected in fetuses A, C, and D, predicting that the risk of developing SMA after birth would be extremely low. Homozygous deletion of SMN1 was present in fetuses B and E suggesting high risk of developing SMA after birth.

[Prokaryotic expression and characterization of N-terminal truncated glycoprotein gp85 of Epstein-Barr virus].

AIM: To construct a prokaryotic recombinant vector of Epstein-Barr virus (EBV) membrane protein gp85, to express the protein in E.coli and characterize the antigenicity of this non-glycosylated protein. METHODS: The BXLF2 gene coding 5'-terminal truncated of EBV gp85 was amplified from the EBV strain B95-8 cell line with specific primers. After identification by the restriction digestion with Hind III and Xho I, the PCR product was inserted into the prokaryotic expression plasmid pGEX-5T and confirmed by sequencing. The constructed prokaryotic expression vector pGEX5T-85N was transformed into the competent E.coli BL21. The expressed recombinant protein gp85N was purified by affinity chromatography, characterized by Western blot, and used immunize BALB/c mice. The titer of antiserum from the immunized mice was detected by ELISA. RESULTS: Sequencing analysis revealed that the obtained truncated BXLF2 gene was identical to that published in GenBank and successfully cloned into pGEX-5T. SDS-PAGE showed that the expressed recombinant protein was partially soluble with a relative molecular mass of 45,000. ELISA results indicated that the expressed gp85N was recognized by that the anti-gp85 mAb and contiserum with high titer was obtained from the immunized mice. CONCLUSION: The obtained recombinant gp85N with an excellent antigenicity should provide preliminary data for characterization of the antibody produced by the immunized mice.

Prenatal molecular diagnosis of adrenoleukodystrophy.

OBJECTIVE: To carry out prenatal diagnosis on two fetuses of different pedigrees with X-linked adrenoleukodystrophy (ALD). METHODS: The amniotic fluid was obtained with the help of a clinical doctor and the genomic DNA was isolated from it. Maternal DNA contamination was excluded by fluorescent STR profiling, The R617G mutation found in the first pedigree was searched in genomic DNA of amniotic fluid cells (AFC) from fetus 1 by amplification refractory mutation system (ARMS) and dot DNA hybridization while the P534R mutation found in pedigree 2 was analyzed in the AFC genomic DNA of fetus 2 by restrictive digestion with Hae II and DNA direct sequencing. RESULTS: A specific band (185 bp) was detected from the genomic DNA of the first fetus and his mother by using mutation primer in ARMS but not from that of the first fetus's father and unrelated controls. DNA dots were visualized only in the fetus 1 and carrier when using the mutation probe in DNA hybridization. In the other ALD family, the PCR product (506 bp) of the second fetus which spanned the site of P534R mutation could not be digested with Hae II and no mutation was detected in the ABCD1 gene from the genomic DNA of the fetus 2 by using DNA direct sequencing. CONCLUSION: Fetus 1 had R617G mutation on his ABCD1 gene and he was an adrenoleukodystrophy hemizygote. Fetus 2 had no P534R mutation on his ABCD1 gene and he was a normal hemizygote.