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The linked alpha-amylase loci Amy 1 and Amy 2 were evaluated for their linkage relationship to the PKU locus using data collected from two (one Czech and one Polish) groups of families. The five sibships informative for Amy 1:PKU give a z score of 1.505 at theta = 0.00 and the eight sibships informative for Amy 2:PKU give a z score of 2.709 at theta = 0.00. Due to the tandem position of Amy 1 and Amy 2 loci, these data could be combined, and linkage between Amy and PKU loci established with a z score 4,214 at theta = 0.00. The practical significance of the linkage, especially for identifying PKU allele carriers, is emphasized.

Physical development scores and clinical condition were evaluated in 403 newborn of phenylketonuric (PKU) heterozygotes. No significant differences were found between this group and the progeny of women from a healthy population. Analysis of mental development scores in 82 non-PKU children age 3-14 years born to heterozygous mothers revealed normal values of psychometric tests.Phenylketonuria follows an autosomal-recessive pattern of inheritance. Partially deficient phenylalanine hydroxylase activity in phenylketonuric (PKU) heterozygotes is manifested by a moderately increased phenylalanine and decreased plasma tyrosine concentration. These abnormalities seem not to have any evident influence on their psychosomatic condition.The problem still to be discussed is the possible influence of disturbed amino acid equilibrium in body fluids on the intrauterine environment, and in consequence on the developing fetus. The aim of the present study was to evaluate the biological value of newborn offspring of PKU heterozygotes and mental developmerit of their healthy non-PKU children. A thorough anamnesis of gestation, the perinatal period and previous pregnancies was performed. MATERIALS AND METHODSThe analysed material includes the offspring of 200 obligatory phenylketonuric heterozygotes-mothers of PKU patients, ascertained by the newborn-screening programme and confirmed by verifying examinations-or patients diagnosed late with clinical symptoms of mental retardation. The total number of children born to these women was 403. Out of this number 238 (58.8%) were PKU patients and 167 (41.2 %) their healthy siblings.Biological maturity of newborn infants was evaluated on the basis of physical development parameters (body weight and length), by Apgar score or in cases of its absence by the evaluation of a paediatrician. The above parameters were analysed separately in PKU homozygotes and in their healthy siblings. The latter group was subdivided as far as possible into heterozygotes, and healthy homozygotes.Heterozygotes were identified with previously elaborated methods: Phe/Tyr and Phe2/Tyr scores based on a single determination of phenylalanine and tyrosine in blood serum and/or plasma, or by phenylalanine tolerance tests followed by a discrimatory analaysis of the results achieved (Duczyfiska et al., 1979(Duczyfiska et al., , 1980.Mental development was evaluated with the Brunet-Lezine psychometric test in children up to 3 years, with the Terman-Merrill test between 3 and 7 years and with the Wechsler Intelligence Scale for Children [WISCJ at school age. Attempts were made to separate heterozygotes from healthy homozygotes in these examinations. RESULTSThe total number of pregnancies analysed was 441; an average of 2.2 per mother. Of these, in 393 (89.1%) the course of pregnancy was regular and in 15 (3.4%) pathology of various types was found. In 35 cases (7.5 %) pregnancy was terminated by spontaneous abortion.Out of 441 pregnancies, 403 (91.4 %) were terminated by deliveries of alive and full-term newborns. The number...

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