In Shenzhen, an AB-type father and an A-type mother gave birth to a child with O-type blood, an improbable occurrence. The man suspected he was unjustly accused of infidelity. Upon further medical examination, the truth revealed he had the rare CisAB blood type.
On October 16, Southern Medical University Shenzhen Hospital published a news report detailing this rare case. CisAB patients have one chromosome carrying both A and B genes, while the other chromosome has only an O gene. Therefore, the father could pass on the O gene to his child.
Doctors remind that CisAB is not a disease but a natural genetic variation. Regular clinical laboratories often misdiagnose CisAB as ordinary AB-type blood. According to public data, the incidence of CisAB in Han and East Asian populations is extremely low, at approximately 1 in 170,000 to 1 in 580,000, making it rare and known as the 'golden blood'.