Recurrence Risk in De Novo 21q21q Translocation Down Syndrome

✍ Scribed by Hall, Bryan D. ;Opitz, John M. ;Reynolds, James F.

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 113 KB
• Volume: 22
• Category: Article
• ISSN: 0148-7299
• DOI: 10.1002/ajmg.1320220228

✦ Synopsis

An article by

Steinberg et a1 [1984]

cautioned against the potential error of counseling families a low-recurrence risk when a previous child has had a de novo 21q21q translocation Down syndrome. They also studied 112 families (ie, sets of parents) with a child with de novo 21q21q translocation Down syndrome, and found that 4 of 112 parents were low-grade mosaics of a 21q21q translocation (n = 3) or carried a pericentric inversion of chromosome 21 (n = 1). Although none of the 112 sets of parents had a second child with Down syndrome, Steinberg et a1 [1984] concluded that the risk of recurrence could be as high as 2-3.6%.

I have studied a family (Fig. 1) whose first-born child died at 4 mo with t(21q21q) down syndrome. The parents had normal chromosomes. The family was told that the recurrence risk was extremely low, perhaps not increased at all. The 25year-old mother had a second pregnancy by another man, which produced another t(21q21q) Down syndrome infant (Fig. 2). The mother was restudied and I cell out of 100 showed a t(21q21q) with karyotype: 46,XX/46,XX, -21, +t(21q21q). Permis-