ABSTRACT
<p><b>OBJECTIVE</b>To analyze the clinical and genetic characteristics of three children with ornithine carbamoyltransferase deficiency(OTCD), and to provide a practical method for gene diagnosis and genetic counseling of the disease.</p><p><b>METHODS</b>All exons of the ornithine carbamoyltransferase (OTC) gene were screened by polymerase chain reaction-DNA direct sequencing in the three OTCD patients.</p><p><b>RESULTS</b>One patient firstly presented as vomiting at 6 month of age. A missense mutation of T262I was detected. His mother had the same mutation without any clinical symptoms. The second patient presented as restlessness, and had a missense mutation of R277W. Gene analysis of his parents was not available. The third patient presented as neonatal lethargy, harbored a missense mutation of I172M. His mother had the same mutation without any clinical symptoms.</p><p><b>CONCLUSION</b>Gene mutation analysis is a feasible way for diagnosing OTCD. Patients with I172M mutation present symptom early, while those with T262I and R277W mutations manifest symptoms later. Gene mutation analysis will be important for asymptomatic and prenatal diagnosis and genetic counseling.</p>