Dopamine Beta-Hydroxylase Deficiency: DBH Sequencing

Dopamine beta-Hydroxylase deficiency (DBHD) is a rare autosomal recessive form of primary autonomic failure characterized by a complete absence of noradrenaline and adrenaline in plasma together with increased dopamine plasma levels. DBH deficiency is mainly characterized by impaired exercise intolerance, severe orthostatic hypotension and persistent ptosis. These findings generally worsen in late adolescence and early adulthood.

DBHD is caused by a mutation in the DBH gene, located on chromosome 9 (9q34). Dopamine beta-hydroxylase is a copper-containg enzyme important in the synthesis of catecholamines, namely the conversion of dopamine to norepinephrine. Biochemical findings in individuals with DBHD include complete absence of plasma norepinephrine and epinephrine in conjunction with elevated plasma dopamine levels.

DBHD occurs when an individual receives two copies of a defective gene, one from each parent. Any person with one copy of the defective DBH gene is a carrier. Carriers do not have DBHD and will not develop the disease. However, if their partner is also a carrier, there is a one in four chance (25%) that their baby will be born with DBHD. There is a three in four chance (75%) that their baby will not have DBHD.

See related information sheet: Dopamine Beta Hydroxylase Deficiency