Search results
Results from the WOW.Com Content Network
Chromosomal translocation. Chromosomal reciprocal translocation of the 4th and 20th chromosome. In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal, and Robertsonian translocation.
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 babies born. [1] It does not usually cause medical problems, though some people may produce gametes ...
Trisomy 21. Down syndrome (also known by the karyotype 47,XX,+21 for females and 47,XY,+21 for males) [98] is mostly caused by a failure of the 21st chromosome to separate during egg or sperm development, known as nondisjunction. [91] As a result, a sperm or egg cell is produced with an extra copy of chromosome 21; this cell thus has 24 ...
1 per 5,000 births [ 3 ] Trisomy 18, also known as Edwards syndrome, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18. [ 3 ] Many parts of the body are affected. [ 3 ] Babies are often born small and have heart defects. [ 3 ] Other features include a small head, small jaw, clenched fists with ...
Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes ' non-sister chromatids that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs in the pachytene stage of prophase I of meiosis during a process called ...
Language links are at the top of the page across from the title.
1 in 4,000 (males), 1 in 8,000 (females) [ 1 ] Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by mild-to-moderate intellectual disability. [ 1 ] The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled. [ 3 ][ 4 ] Physical features may include a long ...
The syndrome is diagnosed in an increasing number of children prenatally by amniocentesis and chorionic villus sampling [24] in order to obtain a chromosome karyotype, where the abnormality can be observed. It is estimated that only 15–20% of children with 47,XYY syndrome are ever diagnosed. Of these, approximately 30% are diagnosed prenatally.