Prenatal diagnosis of two families with megalencephalic leukoencephalopathy with subcortical cysts / 中华围产医学杂志

ABSTRACT

Objectives To provide genetic counseling and prenatal molecular diagnosis for two families with megalencephalic leukoencephalopathy with subcortical cysts (MLC).Methods Two MLC patients (probands 1 and 2) were admitted to the Department of Pediatrics of Peking University First Hospital in June 2011 and June 2009,respectively.Peripheral blood was collected and DNA sequencing was performed for genetic analysis for the two MLC patients and their parents.Amniotic fluid and villus of two fetuses (fetus 1 and 2) were collected at 21+4 and 12+3 weeks of gestational age from their mothers when they were pregnant again.The genomic DNA of the two fetuses was extracted and corresponding sites of MLC1 gene were sequenced.Haplotype analysis using a combination of 3 microsatellite markers (AR,DXS6807 and DXS6797) on chromosome X and sex determining region of Y chromosome was performed to detect maternal cell contamination.Verification of the prenatal molecular diagnosis and follow up study after birth were conducted for both fetuses.Results Macrocephaly,motor development delay and typical findings on brain MRI were identified in the two probands,and were clinically diagnosed with MLC.Compound heterozygous mutations were detected in proband 1 [c.353C＞T (p.T118M) and c.803C＞G (p.T268R)] and proband 2 [c.353C＞T (p.T118M) and c.836T＞C(p.L279P)],respectively.MLC was genetically diagnosed.Heterozygous variation in c.353[c.353C＞T (p.T118M)] and wild c.803C were identified in fetus 1,and both wild c.353C and c.836T were found in fetus 2.No maternal cell contamination was detected in both fetuses.Sequencing the corresponding sites after birth confirmed the prenatal diagnosis,and the head circumference and motor development were normal in fetus 1 at 5 months old.No macrocephaly was found and no DNA sequencing was done in fetus 2 at one month old.Conclusions Genetic counseling and prenatal molecular diagnosis for MLC families combined with clinical and genetic diagnosis are important in preventing MLC.Haplotype analysis with a combination of three microsatellite markers on chromosome X and sex determining region of Y chromosome is useful in detecting maternal cell contamination and avoiding its influence on prenatal diagnosis,and confirming the reliability of prenatal diagnosis.