Thursday, March 6, 2014
WHERE DOES THE CHROMOSOMAL ABNORMALITY OCCUR DURING MEIOSIS?
Often extra or missing chromosomes are caused by a process
known as nondisjuction, occurring during cellular meiosis (the process that
makes reproductive cells – eggs and sperm). During meiosis, the chromosome
pairs line up along the middle of the cell in metaphase and separate during
anaphase. Nondisjunction occurs when a chromosome pair does not separate
properly, resulting in a reproductive cell with two copies of that particular
chromosome (instead of the typical one) and another reproductive cell to not
have any copies of that chromosome. This situation will result in sperm/egg
cells with 22 and 24 chromosomes rather than the typical 23.
(http://www.hudsonalpha.org/education/kits/disorder-detectives/chromosome-abnormalities)
MEDICAL MANAGEMENT
Biosynthesised growth hormone is administered at early ages to improve the stature with 10 cm. Administration of appropriate hormonal therapy may induce the installation of menstruation. Treatment with estrogen and progesterone ensure a harmonious development, puberty and a normal sex life. This treatment prevents osteoporosis and reduces cardiovascular risks of Turner syndrome. Establishment of early therapy, allows the state of pregnancy through in vitro fertilization and birth.
(http://www.doctortipster.com/3328-turner-syndrome.html#ixzz2vFn3zMsg)
EFFECTS OF THE DIFFERENT GENOTYPE ON THE PHENOTYPE
Genotype:
- All or part of one X chromosome missing
Resulting phenotype possibilities:
- Short stature
- swelling of the hands and feet
- broad chest ("shield" chest)
- widely spaced nipples
- low hairline
- low-set ears
- reproductive sterility
- lack of pubertal changes (no menstrual cycle)
- increased weight, obesity
- shield shaped thorax of heart
- shortened metacarpal IV
- Small fingernails
- webbed neck from cystic hygroma in infancy
- high waist-to-hip ratio
- ADHD
- problems with math, social skills, and spatial relations
- etc.
WHAT IS TURNER SYNDROME?
Turner Syndrome is a sex chromosome abnormality that affects about 1 in 2,500 girls. These girl are missing all or part of one X chromosome.
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