Introduction: Peroxisomal disorders are divided into two groups: a) Those with alterations in multiple peroxisomal functions, and b) With alterations in only one peroxisomal function.
Development: During the period 1987-1997, using very long chain fatty acids, plasmalogens and phytanic acid as diagnostic parameters, we diagnosed 116 cases of peroxisomal disorders in Spain. The most frequent (76%) was found to be X-linked adrenoleukodystrophy (X-ALD). Of the five phenotypes described in this condition, the adult cerebral form is seen in a higher percentage in the Spanish population (14%) than in other populations studied (1-3%). Defects in the assembly of peroxisomes made up 18%; the commonest phenotype was that of Zellweger's syndrome (13 cases), followed by neonatal adrenoleukodystrophy (5 cases) and infantile Refsum (2 cases). In the latter two patients, study of the hepatic peroxisomes showed a mosaic distribution. Rhizomelic punctate chondroplasia made up 3%, isolated beta-oxidation defects 2% and defects of plasmalogen synthesis 1%. In X-ALD, diagnosis of an initial case led to the detection of 12 presymptomatic and 70 heterozygote persons. Prenatal diagnoses were made on 10 occasions and 7 fetuses found to be affected. The introduction of the study of ALDP expression in the fibroblasts and the profile of the organic acids in the urine has led to improved diagnosis of these disorders.