Modell/material
- 197 hematologically normal females
	- 23 new born
	- 94 young adult (median 30)
	- 80 eldery (over 75)
- purified neutrofils
- purified T-cells

The model is _human hematopoiesis across age_ and the material is _lineage-purified blood cells_

methods:
1. cell separation (neutrofil and T-cell)
2. x-chromosome inactivation analysis (humana PCR)
3. T-cell clonality check

> [!NOTE]
> They separated neutrophils and T cells, measured X-inactivation skewing, and checked that T cells were not dominating.

### **What was compared / tested**

- **Age groups:** newborn vs young adults vs elderly
- **Cell lineages:** neutrophils vs T cells
- **Readout:** degree of X-chromosome inactivation skewing


### Results
1. X chromosome usage is similar in newborns and young adults.
2. Neutrophils from elderly individuals show strongly uneven X chromosome usage.
3. T-cells show much less uneven X chromosome usage and no dominant clonal expansion

### Figure
![[image-183.png|177x186]] 
Notes
- This graph shows the distribution of X chromosome usage in 23 newborn females
- X-axis: the % of cells using the less common X chromosome.
	- 50% means perfectly (50% maternal / 50% paternal)
	- 0/100% means all cells use the same chromosome
- Y-axis: number of individuals in each group

Conclusion: 
- Newborns mostly show balanced use of the two X chromosomes.

![[image-184.png|177x193]]
Notes
- This graph shows the purified neutrofils from 80 elderly (y >= 75) females
- X and Y axis is the same as in previous graph

Conclusion:
- Elderly neutrophils frequently show strongly uneven X chromosome usage.