Barr body is absent is females having -
Barr body 

Discovered by Murray Ban
Inactive X-chromosome
Usually in female, One X-chromosomes is always inactive and detected as Barr body.
Normal 46 XX → One barr body seen
Super female 47 XXX → Two barr body seen
Klinefelter 47 XXY(males) → Single barr body
Turner 45 XD → Barr body absent
Barr body is seen in nucleus of neutrophils.

Barr body: 

Sex chromative mass seen within nuclei of normal female somatic cell.
Acc. to Lyon hypothesis, one of two x-chromosome in each somatic cell is genetically inactive and repersent barr-body.
Klinefilter syndrome (XXY) → One inactive X-chromosome ban body.
If XXXY = 2 Ban body

XO = 0 Ban body
XY = 0 Ban body
XX = 1 Ban body
46 XX genome
45 XO genome
47 XXX
All of the above