Application of quantitative fluorescence PCR for the prenatal diagnosis of common fetal chromosomal aneuploidies / 中华医学遗传学杂志

OBJECTIVE To assess the value of quantitative fluorescence PCR (QF-PCR) for the prenatal diagnosis of common fetal chromosomal aneuploidies. METHODS A total of 2436 amniotic fluid samples were collected at 18 to 22 gestational weeks. Multiplex QF-PCR was performed with fluorescence-labeled primers specific for 32 polymorphic short tandem repeat (STR) sites on chromosomes 21, 18, 13, X and Y. The PCR products were assayed by capillary electrophoresis. All samples were also assayed by karyotyping. RESULTS Seventy-six (3.12%) samples were diagnosed as chromosomal aneuploidies by QF-PCR, among which 51 were trisomy 21, 12 were trisomy 18, 2 were trisomy 13, and 1 was triploidy. The results were all consistent with those of karyotyping. Ten samples were suspected as sex chromosomal aneuploidies, among which 9 were confirmed, except for 1 case with X structural abnormality. In addition, karyotyping has diagnosed 24 (0.99%) cases of structural abnormalities, only one of which was suspected by QF-PCR with partial abnormal STR results. Two (0.08%) samples were found to be mosaic by karyotyping, one of which was suggested by QF-PCR with cut-off ratios of STR markers. CONCLUSION QF-PCR is reliable for the diagnosis of numerical abnormalities of chromosomes 21, 18, 13, X and Y. The method can serve as an effective technique for rapid prenatal screening of common chromosome aneuploidies in fetus.

[Screening of azoospermia factor microdeletions on Y chromosome in infertile men by QF-PCR].

To assess the application of quantitative fluorescent polymerase chain reaction (QF-PCR) on rapid screening of azoospermia factor (AZF) microdeletions, 1218 infertile men with non-obstructive azoospermia or oligospermia were detected for 9 sequence tagged sites (STSs) in AZF region by multiplex QF-PCR combined with capillary electrophoresis. AMEL (amelogenin) as well as SRY (sex-determining region of Y chromosome) located on short arm of sex chromosome was selected as internal control. Karyotyping was performed on Giemsa-banded metaphase chromosomes of peripheral blood lymphocytes. Of the 1218 patients, 105 (8.62%) were identified as AZF microdeletions. Deletion of AZFc (67.62%) was the most frequent, followed by deletion of AZFb,c (20.95%), AZFb (7.62%) and AZFa (3.81%). Five patients presented with deletions of both AZFa,b,c and AMEL-Y, indicating sex reversal which was confirmed to be 46,XX by karyotyping. Among the 105 patients with AZF microdeletions, 16 were karyotyped as chromosomal anomalies, most commonly 46,XY,Yqh- (75%, 12/16). In addition, of the total 1218 patients examined, 86 patients showed abnormal AMEL-X/AMEL- Y ratio, suggesting a possibility of sex chromosome anomalies, and 68 of them were verified as sex chromosome aneuploid by karyotyping. Multiplex QF-PCR is capable to detect all markers in one reaction and is also suggestive for sex chromosome anomalies. It could serve as an effective technique for screening Y-microdeletions, and thus have general application in diagnosis and treatment of male infertility.

Analysis of DMD gene mutations in 59 families in northern China / 中华检验医学杂志

Objective To detect the DMD gene mutation sites and the regions of breakpoints in Duchenne/Becker muscular dystrophy (DMD/BMD) patients in northern China. Methods Multiplex amplifiable probe hybridization (MLPA) was used to detect the mutation in 59 cases (51 cases with DMD and 8 with BMD) from northern China and dystrophin gene mutations in their parents. Results From northern China and dystrophin gene mutations 59 families found gene deletions in 33 cases of 59 DMD/BMD patients (55.9%), duplications in 6 cases (10. 2%) and point mutation in one case (1.7%). Intron 44 was most frequently affected (n = 13, 33.3%), followed by intron 50 (n = 11, 28.2%) and intron 45 (n=8, 20.5%). The novel mutations were identified, in two patients including two independent duplications carried by patient D1 149 and a point mutation [5208del(A)] carried by patient D1 65, which were not included in Leiden database. In addition, an exon 22 deletion was found in one patient, which was the first reported case in Chinese patients. Conclusions Deletions are mostly located in the hotspot between exon 45 and 50. Duplications mostly occurred in the 5' end of the gene. Intron 44 is the most frequently affected breakpoint in northern Chinese population.