HLA1, HLA2:
HLA1 and 2 retain the Hylobatidae ancestral form.
HLA3:
The fate of the HyA15 centromere is unclear. It could have been lost in the translocation or could have been retained in an inactive form. The sequencing could discriminate between the two hypotheses.
HLA4:
The inactivation of the HyA17 centromere is the most likely hypothesis.