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A longitudinal study of phenylketonuria based on the data of the Budapest Screening Center
Insights
Early treatment of phenylketonuria (PKU) in Hungary, initiated at a mean age of 16.9 days, supports normal physical growth and intellectual development. Despite challenges in dietary control, most PKU patients achieve average IQs and educational success.
Area of Science:
- Medical Genetics
- Pediatrics
- Metabolic Disorders
Background:
- Phenylketonuria (PKU) is a rare genetic disorder.
- Newborn screening programs are crucial for early detection.
- Effective management involves strict dietary control of phenylalanine (Phe).
Purpose of the Study:
- To assess the long-term outcomes of classical PKU patients in Hungary.
- To evaluate the impact of early treatment on growth and development.
- To analyze dietary control adherence and its correlation with patient outcomes.
Main Methods:
- Longitudinal study of 56 classical PKU patients (3 months to 20.5 years).
- Analysis of pretreatment phenylalanine levels, physical growth, and intellectual development.
- Review of dietary control adherence, educational attainment, and career data.
Main Results:
- Incidence of PKU in Hungary found to be approximately 1:9000.
- Early treatment (mean age 16.9 days) did not significantly affect physical growth compared to the general population.
- Mean verbal and nonverbal IQs were within the normal range; 88% attended normal schools.
Conclusions:
- Early initiation of PKU treatment in Hungary is associated with favorable physical and intellectual outcomes.
- While dietary control varied, most patients achieved normal development and educational success.
- This study highlights the effectiveness of PKU management programs in improving patient quality of life.
Abstract:
Between 1975 and 1994 about 1.5 million neonates were screened by Guthrie tests at the phenylketonuria (PKU) Centre in Budapest. In this period 160 children with PKU were found. The corresponding incidence rate is about 1:9000. In a cumulative longitudinal design we investigated 56 patients with classical PKU between the ages of 3 months and 20.5 years. Treatment started at a mean age of 16.9 days (SD = 8.8). On average, pretreatment phenylalanine (Phe) levels were 1956 mumol/l (SD = 864), measured with the fluorometric method. Their Phe levels, physical growth, intellectual development, and performances in achievement tests were analysed. For the entire sample 45% of half year median Phe levels were in the recommended range, 33% represented poor dietary control, 22% were classified as intermediate. Physical growth was not significantly different from the Hungarian average. Mean verbal as well as nonverbal IQs were in the middle of the normal range. For an extended sample of 131 patients not followed longitudinally, mean recent IQ was 99.6 (SD = 16.3). Data concerning educational career were available for 107 patients. Normal schools were attended by 88 patients, 19 were in need of special elementary education. From 40 patients who had already finished elementary school, 17 underwent secondary school education, 1 is a university student, 15 are skilled workers, 4 were semi-skilled, and 4 are unemployed for reasons unrelated to their intellectual status.