One of the challenges that scientists face when classifying a new fossil is that any tiny detail is all that separates one species from another. Further exploration is required to identify another set of characteristics that may help in deciding which organism belongs or create a new class.
Wiskott-Aldrich syndrome is linked with low immunoglobulin G (IgG) and immunoglobulin M (IgM) levels, with normal-to-high immunoglobulin E (IgE) and immunoglobulin A (IgA) levels. Though, young babies in exact may not display classic immunoglobulin irregularities because Wiskott-Aldrich syndrome is linked with attrition in immunologic functions.
One big reason for this is because individuals of the same species often have to fight over shared resources (this means shared food and shared environment).
Because they fight over a limited amount of space and food, competition between individuals within one species can be present and very tough.
On the other hand, having members of different species also possibly means different territories and different food sources. A lion has no quarrel with dolphins, while it can have a lot of fights with lions from different prides (large group of lions).