DSCAM and Dscam are both abbreviations for Down Syndrome Cell Adhesion Molecule. The case difference is significant: DSCAM refers to the human protein, and Dscam refers to its analog in Drosophila

Drosophila

Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...

.

Of particular interest is that Dscam1 could potentially have 38,016 alternative splicing

Alternative splicing

Alternative splicing is a process by which the exons of the RNA produced by transcription of a gene are reconnected in multiple ways during RNA splicing...

 forms from four variable exon

Exon

An exon is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing. The mature RNA molecule can be a messenger RNA...

clusters (12, 48, 33 and 2 alternatives respectively). The diversity of isoforms from alternative splicing of the Dscam1 gene in D. melanogaster allows every neuron in the fly to display a unique set of Dscam proteins on its cell surface. Like Dscam proteins interact to stimulate self-avoidance mechanisms that are essential for normal neural circuit development.