Trinucleotide repeat disorders, also known as microsatellite expansion diseases, are a set of over 50 genetic disorders caused by trinucleotide repeat expansion, a kind of mutation in which repeats of three nucleotides (trinucleotide repeats) increase in copy numbers until they cross a threshold above which they become unstable. Depending on its location, the unstable trinucleotide repeat may cause defects in a protein encoded by a gene; change the regulation of gene expression; produce a toxic RNA, or lead to chromosome instability. In general, the larger the expansion the faster the onset of disease, and the more severe the disease becomes.Trinucleotide repeats are a subset of a larger class of unstable microsatellite repeats that occur throughout all genomes. The first trinucleotide repeat disease to be identified was fragile X syndrome, which has since been mapped to the long arm of the X chromosome. Patients carry from 230 to 4000 CGG repeats in the gene that causes fragile X syndrome, while unaffected individuals have up to 50 repeats and carriers of the disease have 60 to 230 repeats. The chromosomal instability resulting from this trinucleotide expansion presents clinically as intellectual disability, distinctive facial features, and macroorchidism in males. The second DNA-triplet repeat disease, fragile X-E syndrome, was also identified on the X chromosome, but was found to be the result of an expanded CCG repeat.
The proportion of cases of denial, persisting until delivery is about 1 in 2500. Conversely, some non-pregnant women have a very strong belief that they are pregnant along with some of the physical changes. This condition is known as a false pregnancy. Physical signs
Most pregnant women experience a number of symptoms, which can signify pregnancy. A number of early medical signs are associated with pregnancy. These signs include:

the presence of human chorionic gonadotropin (hCG) in the blood and urine
missed menstrual period
implantation bleeding that occurs at implantation of the embryo in the uterus during the third or fourth week after last menstrual period
increased basal body temperature sustained for over two weeks after ovulation
Chadwicks sign (darkening of the cervix, vagina, and vulva)
Goodells sign (softening of the vaginal portion of the cervix)
Hegars sign (softening of the uterine isthmus)
Pigmentation of the linea alba – linea nigra, (darkening of the skin in a midline of the abdomen, resulting from hormonal changes, usually appearing around the middle of pregnancy). Darkening of the nipples and areolas due to an increase in hormones. Biomarkers
Pregnancy detection can be accomplished using one or more various pregnancy tests, which detect hormones generated by the newly formed placenta, serving as biomarkers of pregnancy. Blood and urine tests can detect pregnancy 12 days after implantation. Blood pregnancy tests are more sensitive than urine tests (giving fewer false negatives). Home pregnancy tests are urine tests, and normally detect a pregnancy 12 to 15 days after fertilization.