We hereby reported a case of ring chromosome 18 complicated by the deletion of 18p11.32p11.31 and 18q21.33q23 diagnosed prenatally by G-banding karyotype and chromosomal microarray analysis (CMA). Ultrasound scan indicated a single umbilical artery and intrauterine growth retardation at the second trimester. The result of G-banding karyotyping was 46, XN, r(18)(p11.3q21.3) and CMA indicated that there was a 3.3 Mb deletion at 18p11.32p11.31 and a 16.9 Mb deletion at 18q21.33q23. All these suggested that the fetus might present with clinical manifestations such as growth retardation, epilepsy, speech delay and growth hormone deficiency after birth, so the couple decided to terminate the pregnancy after genetic counseling.

OBJECTIVE: To discuss the value of chromosomal microarray analysis (CMA) for the identification of DMD gene deletions during prenatal diagnosis. METHODS: G-banded karyotyping and CMA were performed on fetuses with ultrasonographic soft markers but no family history for Duchenne/Becker muscular dystrophy (DMD/BMD). Denaturing high-performance liquid chromatograghy (DHPLC) was used to detect DMD gene mutations in umbilical cord blood and peripheral blood samples from the mothers. RESULTS: For fetus 1, analysis of amniocytes showed a normal karyotype, while CMA detected a 119 kb deletion at Xp21.1 (32 565 489 - 32 681 461), which encompassed exons 10 to 16 of the DMD gene. The result was confirmed by DHPLC analysis. The mother was found to have loss of heterozygosity in the same region. For fetus 2, karyotyping of amniocytes also showed a normal male karyotype, while CMA detected a 254 kb deletion at Xp21.1 (32 104 604 - 32 358 874), which encompassed exons 41 to 44 of the DMD gene. The same deletion was not detected in the mother. DHPLC analysis confirmed the presence of both deletions. CONCLUSION Two fetuses harboring DMD gene deletions but without a family history were discovered. CMA can improve the efficiency for detecting single gene diseases caused by deletions.
Dystrophin ; genetics ; Exons ; Female ; Fetus ; Gene Deletion ; Humans ; Incidental Findings ; Male ; Microarray Analysis ; Muscular Dystrophy, Duchenne ; genetics ; Pregnancy