2 Biology of Phenylketonuria Phenylketonuria or PKU is the inability of the body to process and digest the protein phenylalinePhenylaline builds to toxic levels in the tissues, particularly damaging the nervous systemPKU is a chronic disease, but it is possible to greatly reduce the probability of further damage by following a strict low-protein dietPKU is autosomal recessive and carried on chromosome 12
3 Symptoms of PKUMental disabilityDelayed developmentBehavioral, emotional, and social problemsPsychiatric disordersNeurological problems, including seizuresHyperactivityPoor bone strengthEczemaMusty odor in breath, skin, or urineFair skin and blue eyes (because phenylalanine cannot transform into melanin)Abnormally small headBecause high levels of phenylalanine are particularly toxic to the nervous system, many of the symptoms of PKU are brain defects as a direct result of this. This poisoning occurs early in the patient’s life before diagnosis. Damage before diagnosis cannot be undone, but it can be stopped in it’s progression by adapting to an extremely low protein diet.
4 PKU and pregnancyPregnant women with PKU must strictly adhere to treatments and a low-protein diet or risk miscarriage or harm to the child. Even if the child does not inherit PKU, if the mother is not extremely careful, the baby may have birth defects such as:Intellectual disabilityLow birth weightdelayed developmentabnormally small headheart defectsbehavioral problems
5 Diagnosing pkuEvery baby in the United States and several other countries are tested for PKU at birth. The genetic tests administered are able to detect all but a few rare forms of PKU. The rarer forms are tested for only if a parent or doctor expresses concern upon viewing the symptoms of PKU in a young child.
6 Risk FactorsThere is not a particular ethnicity or other biological or environmental factor that is especially susceptible to PKU, although it has been noted that African Americans are LESS likely to inherit or be a carrier of PKU. Basically, it’s luck of the draw that both parents would be a carrier, and there are no predictable patterns to establish who is particularly at risk.
7 Statistics of PKU 2% of the population are carriers of PKU PKU occurs in 1 in 10,000 to 15,000 newbornsThere are less than 20,000 US cases per year, making this disease very rare