Select a case to view its schematic karyotype. Affected chromosomes are outlined.
Schematic only — not diagnostic. These illustrations simplify banding and cannot detect or confirm real cytogenetic abnormalities. Use validated metaphase karyotype images (and FISH/microarray where indicated) for clinical interpretation.
47,XX,+21
Numerical (aneuploidy) — chromosome count changed
Trisomy 21 (Down syndrome)
Numerical: an extra whole chromosome 21 (47 total). Usually from maternal meiotic nondisjunction. Structure of each chromosome is normal.
Clinical note: ~95% free trisomy; ~4% Robertsonian translocation, ~1–2% mosaic — parental karyotyping is relevant for translocation cases.
A · B
1
2
3
4
5
C
6
7
8
9
10
11
12
D · E
13
14
15
16
17
18
F · G · Sex
19
20
21
22
X/Y
Numerical abnormalities
Gain or loss of whole chromosomes (aneuploidy, e.g. +21, 45,X, XXY) or whole sets (polyploidy). Detected by counting; each chromosome's structure is normal.
Structural abnormalities
Breakage and rejoining: deletions, duplications, inversions, translocations. Balanced rearrangements keep total material; unbalanced ones change dosage. Detected by banding comparison of homologs.