Trinucleotide repeat expansion in the beta1 subunit of the sodium pump in manic-depression illness: a negative study.

BACKGROUND

Trinucleotide repeats have become a recognized molecular abnormality in a variety of neuropsychiatric conditions. Bipolar illness has been purported to be a possible trinucleotide repeat-associated disease. Since abnormalities in the expression and regulation of the sodium- and potassium-activated adenosine triphosphatase (Na,K-ATPase) have been documented in bipolar patients and since the beta1 subunit of this pump contains a heterogenous GCC repeat, we decided to investigate the possibility of a repeat expansion in beta1 subunit of Na,K-ATPase in bipolar patients.

METHODS

DNA from postmortem temporal cerebral cortex tissue of five bipolar subjects and five matched normal controls and five lyumphoblastoid cells lines from the Old Order Amish bipolar pedigrees and match normal controls were used for this study. The GCC rich region of beta1 DNA was amplified by polymerase chain reaction (PCR) and sequenced.

RESULTS

The range of GCC repeat in the beta1 gene is between 7 and 9 in our population. This is not different in bipolar patients from normal controls.

LIMITATIONS

This study examined a small number of patients and examined a very limited portion of the locus.

CONCLUSION

It appears that there is not an expansion of the GCC repeat in the beta1 gene in bipolar patients.