TY - JOUR T1 - Ring chromosome 13: lack of distinct syndromes based on different breakpoints on 13q. JF - Journal of Medical Genetics JO - J Med Genet SP - 704 LP - 708 DO - 10.1136/jmg.29.10.704 VL - 29 IS - 10 AU - C A Brandt AU - J M Hertz AU - M B Petersen AU - F Vogel AU - H Noer AU - M Mikkelsen Y1 - 1992/10/01 UR - http://jmg.bmj.com/content/29/10/704.abstract N2 - A stillborn male child with anencephaly and multiple malformations was found to have the karyotype 46,XY,r(13) (p11q21.1). The breakpoint at 13q21.1, determined by high resolution banding, is the most proximal breakpoint ever reported in patients with ring chromosome 13. In situ hybridisation with the probe L1.26 confirmed the derivation from chromosome 13 and DNA polymorphism analysis showed maternal origin of the ring chromosome. Our results, together with a review of previous reports of cases with ring chromosome 13 with identified breakpoints, could neither support the theory of distinct clinical syndromes based on different breakpoints on 13q nor correlate the severity of symptoms with instability of the ring. ER -