We report two cases of a hitherto undescribed pediatric renal neoplasm that is distinctive at the morphological, immunohistochemical, ultrastructural, and cytogenetic levels. On light microscopy, the tumors are composed of nests of polygonal, clear to eosinophilic cells associated with a subpopulation of smaller cells that surround hyaline material. Despite their epithelioid morphology, these tumors do not label immunohistochemically for epithelial markers but instead label focally for melanocytic markers HMB45 and Melan A. The hyaline material is positive with periodic acid-Schiff and methenamine-silver histochemical stains, and labels immunohistochemically for type 4 collagen. Ultrastructural examination confirms that it represents basement membrane material. Cytogenetic analysis reveals the identical t(6;11)(p21.1;q12) chromosome translocation as the sole abnormality in these two tumors, confirming their identity and distinctive nature.

The patient described represents the first reported case of partial deletion 10q. The patient is compared to the partial trisomy 10q syndrome.

Outcrossing rates in natural populations of Lupinus nanus Dougl. have been found to vary from nearly zero to nearly 100 percent (Harding and Horovitz, 1969; Harding, 1970). These studies were based primarily on a group of northern populations of subspecies apricus (Elliott, Harding, and Mankinen; paper VI). The purposes of this paper are (I) to report estimates of outcrossing for the other subspecies of L. nanus, (2) to report estimates of outcrossing for the closely related species, L. bicolor, L. affinis, L. polycarpus, and L. paehylobus, (3) to discuss the relationship between these estimates of outcrossing and autofertility, and (4) to discuss the relationship between outcrossing and phenotypic and genotypic variability maintained in populations. OUTCROSSINGRates of outcrossing have been estimated by progeny testing genetically recessive parents occurring in natural populations of Clarkia (Vasek, 1964(Vasek, , 1965(Vasek, , 1967, Avena (Jain and Marshall, 1967), and Lupinus (Harding and Horovitz, 1969; Harding, 1970). In Lupinus nanus rare flower color mutants (Harding and Mankinen, 1967) are convenient genetic recessives for the estimation of outcrossing. These recessives are also found in the other species of the Nanus Group.The expected frequency of genetically dominant outcrosses arising in progeny of recessives is a(l-q) where a is defined as the frequency of out-* Supported in part by NIH training grant GM 701. -The editor gratefully acknowledges partial financial support towards publication.

Duplication within Xp21 causes female or intersexual development in human embryos with an XY chromosome complement. We have mapped the responsible gene, SRVX (sex reversal X), in XY-sex-reversed maternal half siblings who had inherited the duplication from their mother. The limited size of the duplication in our cases, relative to its extent in other similar cases, allows assignment of the SRVX locus to Xp21.2-->p22.11. We infer that SRVX is part of a pathway of sex-determining genes that includes SRY and SRA1, the latter recently assigned to chromosome 17q. If mutation of SRA1 or SRVX can reverse the sex of the XY fetus, this would explain why mutation within SRY is found only sporadically in women with XY gonadal dysgenesis.

We describe 3 families segregating for a translocation of the nucleolus organizer region (NOR) onto chromosome 4. Review of previously reported cases of translocations involving NOR and chromosome 4 shows that these translocations may be associated with variable reproductive outcomes. We provide evidence that imprinting is not the mechanism responsible for the variable reproductive outcomes in the case of satellited 4p chromosomes; this may offer indirect support for a ribosomal gene position effect. Translocated ribosomal genes may influence the expression of neighboring genes and could explain the variable phenotypes in individuals with satellited nonacrocentric chromosomes. We recommend that prenatal counseling of individuals with satellited nonacrocentric chromosomes should be cautious.