Objective: X-linked adrenoleukodystrophy (X-ALD) is the most common inherited disorder of peroxisomal metabolism which is characterized by demyelination of central nervous system, impaired adrenal cortex and abnormal accumulation of very long chain fatty acids in body fluid and tissues. In this study, the clinical features and the genotype-phenotype relationship were investigated so as to help early diagnosis.
Methods: Clinical data of 89 Chinese patients with X-ALD were analyzed and mutation spectrums in 53 of the patients were investigated by polymerase chain reaction and DNA sequencing.
Results: Of the 89 cases, 60 (67.4%) had childhood cerebral ALD (CCALD, mean age of onset was 6.5 years, range 2 - 10 years), 18 (20.2%) had adolescent cerebral ALD (ACALD, mean age of onset 12.1 years, range 11 - 19 years), 7 (7.9%) had adrenomyeloneuropathy (AMN, mean age of onset 23 years, range 6 - 39.5 years), and two cases were asymptomatic and another 2 had simple Addison's disease only. CCALD was the most common and severe phenotype, visual impairment was the most common initial symptom in CCALD and ACALD patients. Twenty four cases (63%) in whom hydrocortisone and ACTH were measured showed adrenal insufficiency. Forty five different mutations were identified in 53 patients. Missense mutations were the most common. No hotspot mutation was found in these patients and 1415delAG, the most frequent mutation found worldwide seemed not to be the real "hotspot" in these Chinese patients. The same phenotype may be due to diverse genomic mutations. A single mutation may result in different phenotypes even within a family.
Conclusion: The phenotype distribution, initial symptom and gene mutation spectrum of Chinese patients may not be completely consistent with those in other countries. The clinical phenotype of the disease had no definite relationship with the nature of gene mutations.