More than 7000 single gene diseases have been identified and most of them lack effective treatment. As an early form of prenatal diagnosis, preimplantation genetic diagnosis (PGD) is a combination of in vitro fertilization and genetic diagnosis. PGD has been applied in clinics for more than 20 years to avoid the transmission of genetic defects through analysis of embryos at early stages of development. In this paper, a review for the recent advances in PGD for single gene diseases is provided.
Animals ; Female ; Fertilization in Vitro ; Genetic Diseases, Inborn ; diagnosis ; embryology ; genetics ; Humans ; Pregnancy ; Preimplantation Diagnosis ; methods ; trends ; Prenatal Diagnosis ; methods ; trends

Child ; Female ; Forecasting ; Humans ; Mass Screening ; Metabolic Diseases ; diagnosis ; etiology ; Pediatrics ; trends ; Pregnancy ; Prenatal Diagnosis

With the application of BACs-on-Beads (BoBs) and array-comparative genome hybridization (aCGH) technologies in prenatal diagnosis, microdeletion/microduplications at Xp22.3 have been frequently detected. However, the relatively high prevalence and lack of knowledge of such disorders have brought difficulties for clinical genetic counseling. Here, recent progress of research on microdeletion/microduplications at Xp22.3, including epidemiology, pathogenesis, clinical manifestation, and prenatal diagnosis, is reviewed.
Chromosomes, Human, X ; genetics ; Comparative Genomic Hybridization ; Female ; Genetic Counseling ; Humans ; Karyotyping ; Pregnancy ; Prenatal Diagnosis ; Research ; trends

We present frequencies of fetal chromosomal abnormalities in 4,907 prenatal cytogenetic examinations at Samsung Cheil Hospital from 1988 to 1997 for 10 yr duration. Prenatal karyotypes were undertaken in 3,913 amniotic fluid samples, 800 chorionic villi samples, and 194 percutaneous umbilical blood samples. The frequency of fetal abnormal karyotypes was 3.1% (150 cases). Numerical chromosome abnormalities were 87 cases (1.8%) and structural aberrations of chromosomes were 63 cases (1.3%). In the numerical chromosomal abnormalities, the frequency of trisomy 21 was by far the highest (36 cases), followed by trisomy 18 in 22 cases and sex chromosome aneuploidies in 19 cases. In the structural chromosomal aberrations, 5 cases had the inversions in chromosome 2, 7, 17, and Y. Chromosomal deletions in 6 cases and additions in 4 cases were analysed. Of the remaining 47 translocation in abnormal fetuses, reciprocal translocation was in 26 cases and Robertsonian translocation in 21 cases. Among them, 41 cases were balanced translocation and 6 were unbalanced. Thirty five cases of translocation were inherited from one of the parents. Four had de novo chromosome rearrangements, and 8 cases were unknown.
Chromosome Abnormalities/classification/*diagnosis ; Female ; Human ; Institutionalization ; Inversion (Genetics) ; Karyotyping ; Life Change Events ; Pregnancy ; Prenatal Diagnosis/*trends ; Retrospective Studies ; Translocation (Genetics)

OBJECTIVEAlport syndrome (AS) is a progressive renal disease characterized by hematuria and progressive renal failure. X-linked dominance is the major inheritance form of the syndrome, accounting for almost 80% of the cases, caused by mutations in COL4A5 genes. There is currently no effective treatment that has been shown to favorably affect the outcome of AS, so early diagnosis and even prenatal diagnosis is very important.

METHODSIn this study mutation of COL4A5 was detected by amplifying the entire coding sequence mRNA of peripheral blood lymphocytes using nested PCR in two Chinese X-linked dominant Alport syndrome (XLAS) families, then the first prenatal diagnosis of XLAS in China was performed. Mutation analysis of the fetus was performed on both cDNA-based level and DNA-based level of amniocytes. Fetus sex was determined by PCR amplification of SRY as well as karyotypes analysis. Maternal cells contamination was excluded by linkage analysis.

RESULTSThere was a deletion mutation in the proband of the first family, 2696 - 2705 del gtatgatggg in the 32 exon of COL4A5, but the mother did not carry the mutation (de novo). There was a G to A substitution at position 4271 in exon 46 of COL4A5 gene (c.G4271A) in the second family, the mother also carried this mutation. After genetic counselling, only the second family accepted prenatal diagnosis. Both amniocytes cDNA level and amniocytes genomic DNA level based prenatal diagnosis showed that the fetus did not carry the same mutation as the mother. PCR amplification of SRY and karyotypes analysis showed a male fetus. Linkage analysis of X chromosome polymorphic microsatellite markers showed that there was no MCC in amniocytes.

CONCLUSIONBoth cDNA level and DNA level analysis could enhance the accuracy and reliability of prenatal diagnosis. PCR amplification of SRY was faster than karyotypes analysis in the fetal sex determination. Linkage analysis was useful in the detection of maternal cells contamination in amniocytes.

China ; Chromosomes, Human, X ; Collagen Type IV ; genetics ; DNA ; analysis ; DNA Mutational Analysis ; trends ; DNA, Complementary ; analysis ; Exons ; physiology ; Female ; Genetic Counseling ; Genetic Linkage ; Genetic Testing ; Humans ; Mutation ; Nephritis, Hereditary ; diagnosis ; genetics ; Pedigree ; Pregnancy ; Prenatal Diagnosis ; methods ; RNA, Messenger