I agree with the previuos posting that the baby refered to was not lactose intolerant. Reflux isnt a lactose intolerant symptom, diarrhea is.
Lactose is the sugar in human milk so it makes sense that babies arent lactose intolerant.
In residency I had a peds GI attending who was somewhat adamant about this saying congenital lactase deficiency is very rare with only  40 reported cases. (Baldassano,R   "Chronic Diarrhea' Ped Clinics of N Amer Vol38 number 3 June,1991) His rational was that prior to lactose free formulas in the 1960's these lactase deficient hense lactose intolerant babies would have malabsorbed and starved to death. You would then find cases of this when reviewing family histories.
Lactase, the enzyme that diagest lactose in the gut is an "inducable enzyme" or "use it or loss it" put more in and you make more.
Most people do lose their lactase as they get older. I tend to think that lactose intolerence is an adult disease being applied to infants.
An important piont not to confuse, lactose is a sugar while whey and casein are proteins. Cow's milk allergic people are protein allergic, they cant have lactose free milk as it still has the proteins
-Rob