Prenatal diagnosis of mosaic ring chromosome 13 with anencephaly

✍ Scribed by Chih-Ping Chen; Schu-Rern Chern; Chen-Chi Lee; Wen-Lin Chen; Wayseen Wang

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 68 KB
• Volume: 21
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/1097-0223(200102)21:2<102::aid-pd992>3.0.co;2-5

✦ Synopsis

We report on the prenatal diagnosis, genetic analysis and clinical manifestations of a second-trimester fetus with mosaic ring chromosome 13 and anencephaly. A 35-year-old, gravida 3, para 2 woman was referred for genetic counselling at 23 weeks' gestation because of an elevated maternal serum alpha-fetoprotein level of 2.386 multiples of the median. Prenatal ultrasonography showed intrauterine growth retardation and anencephaly. Amniocentesis revealed a karyotype of de novo mos 46,XX,r(13)(p11q32)/45,XX,-r(13) (77%/ 23%). Molecular genetic analysis by quantitative ¯uorescent polymerase chain reaction (PCR) with small tandem repeat markers speci®c for chromosome 13 rapidly con®rmed the maternal origin of the aberrant chromosome and determined the breakpoint at 13q32 between D13S225 (present) and D13S147 (absent). Our present ®nding indicates that anencephaly can be due to mosaic r(13) with a terminal deletion of 13q32-13q34 and an additional secondary rearrangement of loss of r( ). We propose that cytogenetic analysis is bene®cial and warranted in pregnancies with fetal neural tube defects.