STRING 9.05 
HBB [ENSP00000333994]
hemoglobin, beta; Involved in oxygen transport from the lung to the various peripheral tissues
HBZ [ENSP00000252951]
hemoglobin, zeta; The zeta chain is an alpha-type chain of mammalian embryonic hemoglobin, synthesized primarily in the yolk sac
Evidence suggesting a functional link:
Neighborhood in the Genome:  
none / insignificant.
Gene Fusions:  
none / insignificant.
Cooccurence Across Genomes:  
none / insignificant.
none / insignificant.
Experimental/Biochemical Data:   yes (score 0.621).  
Association in Curated Databases:   yes (score 0.720).  
Co-Mentioned in PubMed Abstracts:   yes (score 0.409).  
Combined Score:
Note: the two proteins have some sequence similarity (115.3 bits over 138 amino acids. click here to see the alignment).
Evidence for specific actions:
Binding:yes (score: 0.720)