See also chromatin structure

Prenatal testing is often performed to determine the gender of the fetus or to detect genetic disorders and/or chromosomal abnormalities in the fetus during pregnance. Over 4000 genetic disorders baused by one or more faulty genes have been recognized. Examples include Cystic Fibrosis, Huntington’s Disease, Beta Thalassaemia, Myotonic Dystrophy, Sickle Cell Anemia, Porphyria and Fragil-X-Syndrome. Chromosomal abnormality is cuased by aberrations in chromosome numbers, duplication or absence of chromosomal material and defects in chromosome structure. 

Current availble prenatal genetic tests include chorionic villus samples performed on pregnant woman around 10-12 weeks into the pregnance and aminiocentesis performed at around 16-16 weeks. Fetal cells obtained via these sample procedures are usually tested for chromosomal abnormalities using cytogenetic or fluorescent in situe hybridization (FISH) analyses. 

Pre-natal testing based on differences between Fetus and Mother

–Dection/Diagnosis based on Cell Surface Antigens: 

Zheng (Hum Genet (1997) 100:35-32) discloses antibodies specific for fetal blood cells based on differences between fetal and maternal cell surface antigen expression.

–DetectionDiagnosis based on Fetal DNA Sequence:

Bianchi (US5,641,628 and US 2004/0018509) dicloses a method of detecting the presence or absence of a fetal DNA sequence of interest derived form a sample of blood from a pregnant mother by detecting a fetal DNA sequence of interest with a DNA probe. 

–Detection/Diagnosis based on Fetal Nucleic Acid Epitopes associated with Histones:

Bischoff (US 12/725331) discloses that nucleosome epitopes associated with a histone such as histone H3 especially H3.1 can be used as markers for fetal cells or fetal nucleic acids. Also disclosed are antibodies that target such H3 eptitopes. By isolating fetal nucleic acid genetic composition of the fetus based on the isolated fetal nucleic acid can be accomplished, and this can be indicative of the gender of the fetus or of any disorder of the fetus.  

–Detection/diagnosis based on differences in DNA methylation:

Poon (Clinical chemistry, 48, 1 35-41 (2002) discloses the use of epigenetic markers for the detection of fetal DNA in maternal plasma. Specifically, a differentially methylated region in the human IGF2-H19 locus was studies. 

–Detection of Meconium antigens

Meconium State Pregnancy: Infants born with meconium in their amniotic fluid have lower overall infant assessment scores than their peers born without meconium in the amniotic fluid. Another danger associated with the presence of meconium is the risk of the infant aspirating meconium inot its lungs at the time of birm. Meconium Aspiration Syndrome is a very severe form of pneumonia that is life threatning problem for about 10-20 infants per ten thousand born. Presence of meconium in the amniotic fluid can be diagnosed by visualization of dark staning pigments in the amniotic fluid. A probe has also been described which utilizes illumination of the amnion with light of a specific wavelenght. (US 5,172,693). Antibodies to specific meconium antigens are also used (US 5,514,598).