Chromosomes and cytogenetics
Changes in chromosome number and structure, and the tests that find them.
11 pages
Topics
- Chromosome abnormalities: number and structureAn extra chromosome, a missing one, or a piece lost or moved alters many genes at once and…
- Trisomies 21, 18 and 13, and the 22q11.2 deletionThe three trisomies that reach birth and the commonest microdeletion have features typical…
- Sex chromosome disorders: Klinefelter and TurnerAn extra X chromosome in a male (Klinefelter) or a missing one in a female (Turner) mainly…
- Genetic tests: what each one findsEach genetic test looks at a different scale, from whole chromosomes to single letters of DNA…
- FISH (fluorescence in situ hybridization)FISH uses fluorescent DNA probes that stick to one exact place on a chromosome, to see under the…
- DNA microarraysA microarray is a chip with thousands of DNA probes that measures the expression of many genes…
- 22q11.2 deletion (DiGeorge): the third and fourth pouchesA small piece of chromosome 22 is missing
- Differences of sex development: CAH, AIS and 5α-reductaseConditions in which chromosomes, gonads and genitalia do not follow the typical pattern
Conditions and syndromes
- Down syndrome (trisomy 21)A chromosomal condition from an extra chromosome 21, with intellectual disability, typical…
- 16p11.2 deletion syndromeA small recurrent loss of chromosome 16 that raises the chance of speech delay, autism, obesity…
- Miller–Dieker syndrome (lissencephaly)A deletion on chromosome 17 that stops neurons from migrating in the fetal brain, leaving a…
This section is an index: it gathers pages from Biochemistry, Pathology, Embryology and other sections without repeating them. Educational content; it does not replace a geneticist's assessment or genetic counselling.
Representative model, for educational purposes only.