I have never seen anyone prove that any ball python mutation is a "lethal" gene. That is just speculation. I heard it about the powerball and now they are being produced all over the place. People kept saying spider x spider was lethal and it has been done lots of times with no problems.
The albino clown is a double recesive so from double het breedings it is a 1 inb 16 odds of hitting the double visual. So it is a long process and tough to hit. BHB has produced albino clowns. I do not know who else has them but you will see more of them as there is more material to work with like clowns het albino and albinos het clown to lower the odds of hitting the combo.
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Evan Stahl Reptiles
www.evanstahl.com