Hyperleucine-Isoleucinemia

Definition and Characteristics

This is an extremely rare disorder resulting in failure to thrive, progressive mental deterioration, convulsions, and intermittent dehydration and dyspnea. The reported patients showed mild to moderate elevation of plasma leucine and isoleucine and normal plasma valine and metabolic acidosis without ketosis.

Prevalence

There is only one report of two affected French siblings presenting at 2–3 months of age [1].

Genes

Unknown.

Molecular and Systemic Pathophysiology

Two different branched chain amino acid transferases, BCT1 and BCT2, are known to catalyze the transamination of branched chain amino acids (leucine, isoleucine and valine). It has been suggested that the transamination of valine may be distinct from that of leucine and isoleucine.

Diagnostic Principles

The diagnosis is based on characteristic aminochromatogram in plasma, namely the increase of leucine and isoleucine without the increase of valine.

Therapeutic Principles

Unknown. Low...