Wolf-Hirschhorn syndrome
46,XX,del(4)(p16.3)
Also known as: 4p deletion, 4p minus
46,XX,del(4)(p16.3) is the karyotype of Wolf-Hirschhorn syndrome, a deletion of the tip of the short arm of chromosome 4. It causes a distinctive facial appearance with severe growth and developmental delay.
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What banding sees: Many 4p16.3 deletions are too small to see with banding, so a normal karyotype does not rule Wolf-Hirschhorn syndrome out. FISH or a microarray is what confirms it. The drawing above shows where the missing segment lies, not what would be visible down a microscope.
What the notation means
46count,XXsex chromosomes,del(4)(p16.3)abnormality
The shape of this abnormality
delsymbol(4)chromosomes(p16.3)breakpoints
- (4)
- one chromosome, so one group of breakpoints follows.
- (p16.3)
- one band: everything from it out to the tip is lost (a terminal deletion).
- count · sex chromosomes
- a normal count and the usual female sex chromosomes
- abnormality
- a terminal DELETION of chromosome 4: everything distal to 4p16.3 (out to the tip) is lost
Clinical notes
del(4p), Wolf–Hirschhorn syndrome
Deletion of 4p16.3. 'Greek warrior helmet' facies, growth delay, seizures, intellectual disability.