Analysis of a very large trinucleotide repeat in a patient with juvenile Huntington's disease

A patient with juvenile Huntington's disease (HD) of probable maternal inhe ritance is reported. The expanded IT-15 allele was only detected with the u se of modified PCR and Southern transfer techniques, which showed a CAG tri nucleotide repeat expansion of approximately 250 repeats-the largest CAG ex pansion reported within the huntingtin gene. This case emphasizes the need for communication between the diagnostic laboratory and the clinician to de fine the molecular genetics of unusual cases.