Expand DQB alleles to also contain their linked alpha chains

[iskandr]

From https://en.wikipedia.org/wiki/Major_histocompatibility_complex,_class_II,_DQ_alpha_1:

DQB1 DQA1
0504 0102
0604 0102
0605 0102
0609 0102
---
0502 {0102, 0103}
---
0601 0103
0603 0103
---
0501 {0101, 0103, 0104}
---
0602 {0102, 0103, 0104, 0303}
---
0503 0104
---
0201 0501
0202 {0201,0301} 
0302 0301
0303 {0201, 0401}
0301 {0101, 0303, 0505, 0601}
0401 0401
0402 0401

[iskandr]

Some frequencies list in table on https://en.wikipedia.org/wiki/HLA-DQ but I want to find the source and capture these frequencies both globally and as a function of ethnic group (otherwise we're probably just assuming frequencies in an arbitrary population)