Down syndrome

✍ Scribed by Shapiro, Burton L.

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 52 KB
• Volume: 16
• Category: Article
• ISSN: 0148-7299
• DOI: 10.1002/ajmg.1320160422

✦ Synopsis

Letter to the Editor: Down Syndrome

To the Editor:

Carothers' letter is interesting. If his hypothesis is testable, it is surely welcome. If it is correct, he has made a nice contribution to our understanding of a portion of the Down syndrome (DS) phenotype. Carothers suggests that dosage effects of polymorphic loci on chromosome 21 explain the increased variance of many metric traits in DS. This suggestion supposes a relatively enormous contribution of number 21 loci to diverse polygenic metric traits, but ignores the chromosomal dispersion of loci involved in the genesis of metric traits as well as the small size of chromosome 21.

Parsimony is, of course, attractive, but even Scrooge finally learned of its shortcomings. Can "the dosage effects of polymorphic genes" (Carothers) account for " . . . ii) amplified instability of developmental pathways, iii) reduced precision of physiological homeostatic controls, and iv) generalized increased morbidity . . . " [Shapiro, 19831 in DS even if it does contribute to increased variance of metric traits in DS? I think not. These consequences of the disruption-of-homeostasis model are coequal with the increased variance considered by Carothers.

Finally, the "clinical implications" of his suggestion are not apparent to me. Data would be most welcome.