A Case Report of a Child with a Marker Chromosome Presenting as Isodicentric Yp and Literature Review.

Abnormal Y chromosome includes Yq– of various extents (excluding normal Yq variation), Yp–, r(Y), and isochromosomes or isodicentric chromosomes, written variously as i(Yp), idic(Yp), i(Yq), and idic(Yq) [1]. The least rare of these rare conditions is the Y isochromosome, or isodicentric chromosome, usually seen as 46,X,i(Y)(p10) or 46,X,i(Y) (q11), in which the essential imbalance is a double dose of Yp material, and absence (or nearly so) of Yq [1]. There have only been a few definite reports of nonmosaic isodicentric Yp [2-4]. We describe a case with non-mosaic isochromosome of the short arm of Y in which the phenotype includes mild developmental delay, heart defects, normal genitalia, and normal stature. In addition, we review the literature associated with non-mosaic isochromosome of the short arm of Y.