create new term COL1A2-related Ehlers-Danlos syndrome

[nicolevasilevsky]

close #8760

and add synonym to 'Ehlers-Danlos syndrome, cardiac valvular type'
close #8761

[cmungall]

how is this different from https://omim.org/entry/617821?

[nicolevasilevsky]

@cmungall this was requested as a grouping term to group

• 'combined osteogenesis imperfecta and Ehlers-Danlos syndrome 2'
• 'Ehlers-Danlos syndrome, arthrochalasia type, 2'
• 'Ehlers-Danlos syndrome, cardiac valvular type'

All three of these are EDS with a variation in COL1A2.

If 'Ehlers-Danlos syndrome, arthrochalasia type, 2' is equivalent to COL1A2-related Ehlers-Danlos syndrome, then 'Ehlers-Danlos syndrome, cardiac valvular type' and 'combined osteogenesis imperfecta and Ehlers-Danlos syndrome 2' would be inferred to be a subclasses, and that does not seem correct to me (based on the definitions of the terms and it would also be classifying two OMIM terms under an OMIM term).

Please let me know your thoughts, thanks!