[Embryofetopathy of the newborn infant of a phenylketonuric mother. A diagnosis not to be missed].

Children with phenylketonuria (PKU) detected in the neonatal period and who have received the appropriate diet develop normally whatever their sex. However, female PKU patients who, before becoming pregnant, do not take the precaution to follow a diet bringing phenylalanine to "normal levels" (2 to 5 mg in 100 ml of blood) give birth to children presenting with severe embryofoetal damage (e.g. intrauterine growth retardation, microcephaly, mental retardation, various malformations) directly due to their hyperphenylalaninaemia (20 mg or more in 100 ml of blood under a free diet). It is important to know these facts, since the benefits of systematic neonatal PKU detection may be cancelled by this late complication. The therapeutic approach in such cases is a follows: 1. Young women with known PKU must be informed of this risk and how it can be avoided by a preconception therapeutic diet. This means that they must permanently reside in the same geographical area, receive an adequate information at the end of puberty, use and effective contraception method and program their pregnancies preceded by a return to low phenylalanine diet. 2. Doctors must remember that because PKU detection has not become systematic until 1978, PKU girls of child-bearing are remain undetected, that they are not always mentally debilitated and can normally five birth to children with embryofoetal damage. In case of e.g. unexplained intrauterine growth retardation or microcephaly, it is necessary to perform a Guthrie test on the woman, since a prenatal diagnosis may lead to therapeutic abortion, and a postnatal diagnosis to a genetic counselling which will avoid recurrences.(ABSTRACT TRUNCATED AT 250 WORDS)