Delineation of three structural Y chromosome aberrations combined molecular techniques / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the structure of Y chromosome aberrations and recombinant mechanisms for three patients.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>Y chromosome aberrations are variable. Combined use of MLPA, STSs, FISH and SNP array is effective for revealing the breakpoints and recombinant mechanisms.</p>

Analysis of small supernumerary marker chromosome 15q11 in four infertile males / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the origins of small supernumerary marker chromosomes (sSMCs) identified in 4 infertile males.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Prenatal diagnosis of 5 fetuses with high risk of developing spinal muscular atrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform prenatal diagnosis for 5 pregnant women who had given birth to children with spinal muscular atrophy (SMA).</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>