In the unusual hereditary metabolic disorder known as metachromatic leukodystrophy (MLD) the affected person has a marked depletion in the leukocyte concentration of arylsulfatase A. In our study of two families this generalization holds for both late infantile and juvenile forms of the disease. In addition, the white blood cells (WBC) of the carrier appear to contain an amount of the enzyme which is intermediate between that of the affected patient and controls, which suggests a gene-dose effect.
Hackett TN, Hackett RJ, Bray PF, Madsen JA. Chemical Detection of Metachromatic Leukodystrophy in Disease and Carrier States. Am J Dis Child. 1971;122(3):223-225. doi:10.1001/archpedi.1971.02110030081008