Human Genetics

, Volume 108, Issue 1, pp 14–19

A silent mutation induces exon skipping in the phenylalanine hydroxylase gene in phenylketonuria

  • Hung-Kun  Chao
  • Kwang-Jen Hsiao
  • Tsung-Sheng Su
Original Investigation

DOI: 10.1007/s004390000435

Cite this article as:
Chao, H., Hsiao, K. & Su, T. Hum Genet (2001) 108: 14. doi:10.1007/s004390000435

Abstract.

An A→T substitution in cDNA nucleotide 1197 (c.1197A/T) of the human phenylalanine hydroxylase (PAH) gene has been regarded as a silent mutation, because both the wild-type (GUA) and the mutant (GUU) alleles encode a valine residue at codon 399 (V399 V). The nucleotide c.1197 is located at the 3'-end of exon 11at position –3 of the exon-intron junction. To explore whether the substitution exerts any effects on the processing of the PAH mRNA, illegitimate PAH transcripts from lymphoblast cultures of a phenylketonuria (PKU) patient heterozygous for c.1197A/T were analyzed by the polymerase chain reaction following reverse-transcription (RT-PCR). mRNAs with an exon 11 deletion were revealed. Furthermore, by using an R408 W mutation in the paternal allele as a marker, sequence analysis of the RT-PCR products indicates that virtually all PAH transcripts from the maternal allele with the c.1197A/T substitution do not contain exon 11. To address whether this substitution is the main determinant for exon skipping, PAH mini-genes with or without the substitution were constructed and transfected to a human hepatoma cell line. Analysis of the transcription products by S1 nuclease mapping clearly indicated that such exon 11 skipping was directly associated with the c.1197A/T substitution. Thus, this study demonstrates that the c.1197A/T substitution in the PAH gene is not just a neutral polymorphism but a mutation that induces post-transcriptional skipping of exon 11 leading to a PKU phenotype.

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • Hung-Kun  Chao
    • 1
  • Kwang-Jen Hsiao
    • 1
  • Tsung-Sheng Su
    • 1
  1. 1.Department of Medical Research and Education,Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China 11217
  2. 2.Institute of Genetics, National Yang-Ming University, Taiwan, Republic of China
  3. 3.Institute of Microbiology & Immunology, National Yang-Ming University, Taiwan, Republic of China