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[citation needed] An example of trisomy in humans is Down syndrome, which is a developmental disorder caused by an extra copy of chromosome 21; the disorder is therefore also called "trisomy 21". [7] An example of monosomy in humans is Turner syndrome, where the individual is born with only one sex chromosome, an X. [8]
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child. There are over 6,000 known genetic disorders in humans.
Most cells in the human body have 23 pairs of chromosomes, or a total of 46 chromosomes.(The sperm and egg, or gametes, each have 23 unpaired chromosomes, and red blood cells in bone marrow have a nucleus at first but those red blood cells that are active in blood lose their nucleus and thus they end up having no nucleus and therefore no chromosomes.) [8]
Chromosome 16 abnormalities; Chromosome 18 abnormalities; Chromosome 20 abnormalities; Chromosome 22 abnormalities; Cleft lip/palate; Cleidocranial dysostosis; Club foot; Congenital adrenal hyperplasia (CAH) Congenital central hypoventilation syndrome; Congenital diaphragmatic hernia (CDH) Congenital Disorder of Glycosylation (CDG) Congenital ...
Monosomy, with the presence of only one chromosome (instead of the typical two in humans) from a pair, which affects chromosome 14. Fetuses with monosomy 14 are not viable. [ 1 ] Only mosaic cases exist and these usually present with severe symptoms such as intellectual disability , ocular colobomata , microcephaly , and seizures .
Trisomy 21 – Down syndrome, an example of a polysomy at chromosome 21 Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies. [1]
A Robertsonian translocation. The short arms of the chromosomes (shown on right) are often lost . Robertsonian translocation (ROB) is a chromosomal abnormality where the entire long arms of two different chromosomes become fused to each other. It is the most common form of chromosomal translocation in humans, affecting 1 out of every 1,000 ...
One of them consists in micro-deletions of the chromosome region 15q11–q13. 70% of patients present a 5–7-Mb de novo deletion in the proximal region of the paternal chromosome 15. The second frequent genetic abnormality (~ 25–30% of cases) is maternal uniparental disomy of chromosome 15.