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Occasionally, there is a single umbilical artery (SUA) (Vasa praevia) present in the umbilical cord, as opposed to the usual two. [1] This is sometimes also called a two-vessel umbilical cord, or two-vessel cord. Approximately, this affects between 1 in 100 and 1 in 500 pregnancies, making it the most common umbilical abnormality.
Chromosome 15 is one of the 23 pairs of chromosomes in humans.People normally have two copies of this chromosome. Chromosome 15 spans about 99.7 million base pairs (the building material of DNA) and represents between 3% and 3.5% of the total DNA in cells.
Smith–Magenis syndrome (SMS), also known as 17p- syndrome, is a microdeletion syndrome characterized by an abnormality in the short (p) arm of chromosome 17. [1] It has features including intellectual disability, facial abnormalities, difficulty sleeping, and numerous behavioral problems such as self-harm.
Haplolethal regions - Two regions on chromosome 18 have never been found to be deleted. They are located between the centromere and 22,826,284 bp (18q11.2) and between 43,832,732 and 45,297,446 bp (18q21.1). The genes in these regions are thought to be lethal when deleted.
CPM is detected in approximately 1-2% of ongoing pregnancies that are studied by chorionic villus sampling (CVS) at 10 to 12 weeks of pregnancy. Chorionic villus sampling is a prenatal procedure which involves a placental biopsy .
Monosomy 9p (also known as Alfi's Syndrome or simply 9P-) is a rare chromosomal disorder in which some DNA is missing or has been deleted on the short arm region, "p", of one copy of chromosome 9 (9p22.2-p23). [1] [2] This deletion either happens de novo or as a result of a parent having the chromosome abnormality. [3]
At 12 weeks of gestational age, an "average" nuchal thickness of 2.18mm has been observed; however, up to 13% of chromosomally normal fetuses present with a nuchal translucency of greater than 2.5mm. Thus for even greater accuracy of predicting risks, the outcome of the nuchal scan may be combined with the results of simultaneous maternal blood ...
[11] [12] Eight years later in 1988, the first clinical case of UPD was reported and involved a girl with cystic fibrosis and short stature who carried two copies of maternal chromosome 7. [13] Since 1991, out of the 47 possible disomies, 29 have been identified among individuals ascertained for medical reasons.