Fuentes SLE, Contreras RJ, Alonso JE, Martínez RL

Language: Spanish
References: 21
Page: 36-40
PDF size: 495.96 Kb.

ABSTRACT

Hyperphenylalanines are a group of innate metabolism errors of the phenylalanine amino acid, due to deficiencies in its conversion to tyrosine. From the biochemical point of view they are characterized by an increase in phenylalanine levels in serum and low or normal tyrosine values, while from the clinical point of view they are associated with intellectual impairment. In this work the methodology applied for the determination of the optimal cutting point for the phenylalanine/tyrosine ratio is described, as the second diagnostic criterion applied in The National Center for Medical Genetics in Cuba. A normality study for the variable under study was carried out applying the Shapiro-Wilk test, analyzing the association of phenylalanine levels with sex and age variables by means of the U -Mann-Whitney test and the Spearman correlation coefficient respectively, with a significance level equal to p=0,05, using IBM’s SPSS Statistics 20 software for statistical analysis. The optimal cutting point was found determining the value that, at the same time, allowed minimizing the number of wrong diagnoses, while maximizing sensitivity, specificity and Youden’s index, resulting in an optimal cutting value equal to 2 for the phen/tyr ratio. Afterwards the obtained optimal cutting point was validated in a sample of 526 neonates. These result will allow applying the ratio phen/tyr as a second diagnostic criterion for hyperphenylalaninemias in Cuba.

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