A rapid and sensitive protocol for prenatal molecular diagnosis of X-linked adrenoleukodystrophy.

BACKGROUND: X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative genetic disease characterized by progressive demylination of the brain, adrenal insufficiency and elevated VLCFA level. ABCD1gene is the disease gene and more than 500 unique mutations in the ABCD1gene have been recorded in the database, approximately 60% of which are noncurrent ones. Although great progress has been made in the treatment of X-ALD, prenatal diagnosis is still badly needed by X-ALD-stricken families.

METHODS: Twelve high-risk fetuses entered this study. Amniotic fluid (AF) was divided into two parts, with one part being used directly to isolate genomic DNA and debris from the other part for amniotic fluid cells (AFC) culturing. STR profiling was performed to evaluate maternal contamination of AFC genomic DNA. Two different molecular approaches, be they any two of direct sequencing, PCR-RFLP, ARMS, dot hybridization and DHPLC, were applied to determine whether the mutation identified in the index patient was found in the fetus.

RESULTS: The genotypes of all 12 fetuses were determined, among which 2 were diagnosed as ALD males, 5 unaffected males, 1 heterozygote, and 4 normal unaffected females. A total of 9 families sent samples of umbilical blood at the time of delivery, and results of molecular checking of these samples agreed with those of prenatal diagnosis. Up until now, no ALD-related abnormalities were reported postnatally.

CONCLUSION: An in-house protocol for the prenatal molecular diagnosis of X-ALD was established, and this protocol would provide accurate and rapid prenatal genetic service to X-ALD-stricken families.