Infant Phenylketonuria

An autosomal recessive congenital disease in which there is an enzyme deficit that prevents the metabolization of the essential amino acid phenylalanine (Phe) to the amino acid tyrosine, producing an accumulation of Phe in the body that, untreated, damages the central nervous system causing mental deficiency.
The treatment consists of restricting from one’s diet foods that contain large quantities of Phe, especially pulses, soy, meat, fish, eggs, cereals (except rice and corn), dairy products and the sweetener aspartame.
This restriction, which is fundamental in the initial stage of life, is recommended to be life-long.

Since 1980 when it was discovered that breastmilk has a low concentration of Phe (29-64 mg / dL), lower than milk formula (Lawrence 2016 p.493, Banta-Wright 2012), breastfeeding, supplemented with special formulas that are Phe-free, is now considered an indicated feeding method for infants affected by phenylketonuria (Kose 2017, Lamônica 2012, Cornejo 2003, Duncan 1997).

There are several dietary control protocols (Duncan 1997). Plasma Phe checks should be frequent (initially weekly) and be maintained between 2 and 6 mg/dL (120-360 mmol/L) varying the amount of special formula offered in each feed before breastfeeding (Lawrence 2016 p.493, Lamônica 2012) or the daily number of breastmilk feeds "ad libitum" alternated with special formula feeds (van Rijn 2003) based on these levels.

More than half of the diet can be breastmilk (Lawrence 2016 p.493). Mothers must handle breastmilk extraction and storage techniques well.
They should not take aspartame (Lawrence 2016 p.315).
Control and monitoring must be undertaken by specialized personnel.

Weight gain was similar or greater and there is equal or more frequency of Phe plasma levels within the range in breastfed phenylketonuric infants than in non-breastfed infants (Kose 2017, Banta-Wright 2012, Kanufre 2009, Hinrichs 1994). The number of days needed for Phe levels to return to normal was similar (7-8 days on average) in both groups (Kanufre 2009, Motzfeldt 1999).

Growth (weight, height, head circumference) was monitored in 74 phenylketonuric infants breastfed for an average of 7 months, ranging from 1 to 16 months (Motzfeldt 1999).

Eight out of ten large European centres treating infants with phenylketonuria promote breastfeeding within dietary procedure (Ahring 2009).

With respect to not having been breastfed, breastfeeding prior to the diagnosis of phenylketonuria improved neurodevelopment in schoolchildren, with an average of 13 points higher in IQ (Riva 1996).

Despite all its advantages, abandonment and shorter duration of breastfeeding has been observed following the diagnosis of phenylketonuria in infants, partly due to the difficulty of measuring Phe intake (Banta-Wright 2014).

• Aspartame (Very Low Risk)
• Maternal Phenylketonuria (Very Low Risk)

Writings

• Φαινυλκετονουρία βρέφους (Greek)