frequent sequence variant in the human tyrosine hydroxylase gene

Hum Genet (1995) 95:716 �9 Springer-Verlag 1995

Barbara Lt idecke �9 Klaus Bar tholom6

Frequent sequence variant in the human tyrosine hydroxylase gene

Received: 6 October 1994 / Revised: 16 November 1994

A b s t r a c t A po lymorph i sm of human tyrosine hydroxy- lase changing the amino acid *tVal to 8JMet is located in exon 2 of the human tyrosine hydroxy lase gene.

Introduction

Tyrosine hydroxylase (TH, E.C. 1.14.16.2) is the key en- zyme in the biosynthesis of the neurotransmitter dopamine. Many at tempts have fai led to correlate psychiatr ic disor- ders with an impai red TH (Beyer ley et al. 1992). Dur ing our search for muta t ions in patients with Segawa ' s syn- d rome (Segawa et al. 1971) we per formed sequence anal- ysis of the TH gene (exon 1-12, excluding exon 9 and 10).

Materials and methods

The site that encodes exon 2 of the TH gene was amplified using the primers 5"-AGCTATGACAAAGGGTGGAGG-3" and 5 "-GGA- TCCCTCAAAAACAGG-3". The polymerase chain reaction (PCR) was performed in 100 lal volumes containing 1 lag genomic DNA, 300 ng of each primer, 200 laM of each dNTP in 50 mM KCI, 10 raM TR1S-HCI, 1.5 mM MgC12, 0.01% (w/v) gelatin and 2.5 U Taq polymerase. PCR conditions were: 33 temperature cycles con- sisting of 1 min at 95~ 1 min at 65~ and 3.45 rain at 73~

The 1-kb amplification product was sequenced using the primer 5"-CTCAAACACCTTCACGCGG-3".

Results

A point mutat ion changing codon 81 from G T G to ATG with a result ing amino acid change f rom Val to Met with respect to the amino acid number ing of HTH1 (Gr ima et al. 1987) was found in exon 2 o f the gene. Six out of

seven Segawa patients s tudied carr ied the mutat ion, three of them in the homoz ygous form. In a control group of 35 heal thy persons 20 also carr ied the mutat ion, 4 in the ho- mozygous form.

Discussion

The purpose of this study was to find mutat ions in the TH gene that may be correlated with Segawa ' s syndrome. This a im seems reasonable because patients with this syn- d rome react ex t remely posi t ively to a low dose therapy of d ihydroxypheny la lan ine (DOPA), the product of TH.

The mutat ion found in exon 2 does not cause Segawa ' s syndrome as 11.5% of the normal controls carry this mu- tation in the homozygous form. Whether an addit ional mutat ion in the TH gene or compound he terozygos is causes another disease is not known. This po lymorph i sm has been reported to the Genome Data Base.

Acknowledgements This work was supported by the Deutsche Forschungsgemeinschaft, grant Ba 385/12-1.

References

Byerley W, Plaetke R, Hoff M, Jensen S, Holik J, Lubbers A, Reimherr F, Mellon C (1992) Tyrosine hydroxylase gene not linked to manic-depression in seven of eight pedigrees. Hum Hered 42 : 259-263

Grima B, Lamouroux A, Boni C, Julien J-F, Javoy-Agid F, Mallet J (1987) A single gene encoding multiple tyrosine hydroxy- lases with different predicted functional characteristics. Nature 326:707-711

Segawa M, Ohmi K, Itoh S (1971) Childhood basal ganglia dis- ease with remarkable response to L-Dopa, "hereditary basal ganglia disease with marked diurnal fluctations". Therapie 24 : 667 672

B. Liidecke �9 K. Bartholom6 (1~) University Children's Hospital, Alexandrinenstrasse 5, D-44791 Bochum, Germany