This figure represents the output of our 2 meta-analytic models. The first model describes the relationship of Phe and IQ when Phe was measured “historically” (more than 12 months before IQ measurement). In the second model, Phe and IQ were measured concurrently (within 6 weeks of IQ measurement). Lines in the figure correspond to historical measures of Phe and the probability of IQ < 85 as a function of Phe when measured concurrently. Lines illustrating historical measures of Phe demonstrate increasing probability of low IQ at higher Phe measures, regardless of whether the effect is being measured during childhood or beyond, with a stronger association seen between Phe measured in early childhood and later IQ. Lines describing the probability of IQ < 85 as a function of Phe when measured concurrently show a lack of strong association in measurements taken concurrently during the critical period.

Figure CProbability of IQ <85 at varying blood Phe levels and Phe measurement times

IQ = intelligence quotient; Phe = phenylalanine; Pr = probability

From: Executive Summary

Cover of Adjuvant Treatment for Phenylketonuria (PKU)
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Lindegren ML, Krishnaswami S, Fonnesbeck C, et al.

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