A 9-BP DELETION (2320DEL9) ON THE BACKGROUND OF THE ARYLSULFATASE-A PSEUDODEFICIENCY ALLELE IN A METACHROMATIC LEUKODYSTROPHY PATIENT AND IN A PATIENT WITH NONPROGRESSIVE NEUROLOGICAL SYMPTOMS

A 9-bp deletion (2320del9) was detected in the arylsulfatase A genes o f a patient with late infantile metachromatic leukodystrophy and of a patient with nonprogressive neurological symptoms and very low arylsul fatase A activity. Both patients are heterozygous for the deletion, wh ich involves codons 406-408 and causes loss of a Ser-Asp-Thr tract-in the predicted protein, Tn both patients the 9-bp deletion lies in a ps eudodeficiency; allele., The patient with metachromatic leukodystrophy carries the common 459 + 1G > A mutation in the other allele, The oth er patient is homozygous for the pseudodeficiency allele, and conseque ntly is a compound heterozygote for a metachromatic leukodystrophy all ele and a pseudodeficiency allele. ,We hypothesize that the compound h eterozygosity predisposes to the development of nonprogressive neurolo gical symptoms in the presence of additional, still unknown, genetic o r nongenetic factors.