Prenatal DNA Diagnosis of Harlequin Ichthyosis Possible
DNA-based analysis of causative gene can be conducted on amniotic fluid
THURSDAY, March 22 (HealthDay News) -- Prenatal diagnosis of harlequin ichthyosis is possible by DNA analysis of the causative gene in amniotic fluid as opposed to electron microscopy of fetal skin biopsy samples, according to a study in the March issue of the Journal of Investigative Dermatology.
Masashi Akiyama, M.D., Ph.D., from Hokkaido University Graduate School of Medicine in Sapporo, Japan, and colleagues describe the case of a French couple whose first child was afflicted with harlequin ichthyosis and died soon after birth. After the birth of a second healthy child, the couple requested prenatal testing on their third pregnancy.
Analysis of the ABCA12 gene responsible for the disorder from the first deceased child showed two novel mutations, a maternal nonsense mutation and a paternal mutation that was predicted to be a splice mutation.
Using amniotic fluid from the third pregnancy, the researchers found that the fetus contained the same two mutations, leading the parents to terminate the pregnancy. An analysis of keratinocytes from the abortus showed that six abnormally spliced products from the ABCA12 allele carrying the splice site mutation were present, which led to either premature termination or shortened proteins.
"This report provides evidence for residual ABCA12 expression in harlequin ichthyosis, and demonstrates the efficiency of early DNA-based prenatal diagnosis of harlequin ichthyosis," Akiyama and colleagues conclude.