Why Beta-casein Protein is so important?

In milk 80% of total protein is casein protein, about 20% is whey protein & glycoprotein has very small traces. 30-35% of the casein (equivalent to two teaspoons in a liter of milk) is beta-casein, of which there are several varieties, determined by the genes of the cow. The most common of these variants are A1 and A2.Beta-casein is a protein with 209 amino acids chain. At its 67thposition Desi Cow has amino acid proline which is strongly bonded with a small protein called Beta casomorphine-7 (BCM-7) which prevents it from getting into the milk. On the other side European breed cows has histidine instead of proline on the 67th position of amino acids. As histidine holds the weak bond with BCM-7 so it is easily released in the GI tract of animals & enter the human body and interact with digestive system and internal organs.
Why BCM-7 is harmful (devil in the milk):
BCM7 is known to be an opioid – a type of narcotic of which studies suggest that it can have a variety of effects like
1. It does pass into the blood of babies who were fed infant formula which led to delayed psycho-motor (brain to muscle) development.
2. It is also associated as a risk factor for type-1 diabetes, coronary heart disease, mental disorders like autism & schizophrenia because it may enter our brain through blood.
3. It may cause digestive disorders like irritable bowel syndrome or a weak gut.