RFLP and DNA sequence analysis revealed that they were heteroallelic for the common G(934)-->A substitution in exon 8 of the hLAL gene and a mutation which, if inherited on both alleles, would be expected to result in complete loss of enzyme activity and to cause Wolman disease.
DNA sequence and restriction fragment length polymorphism analysis demonstrated that the patient was a compound heterozygote for the prevalent CESD exon 8 splice site mutation (G934A) and the deletion of a C (nucleotide 673, 674, or 675) in exon 6 of the hLAL gene, resulting in premature termination of protein translation at residue 195.