Mucopolysaccharidoses (MPS) is a rare disease in humans; in several forms of this disease, patients have severely limited mobility of limbs. Motivated by the fact that these patients experience difficulties in using computers, especially the standard mechanical keyboard (QWERTY layout), this research focuses on designing a new virtual keyboard specifically catering to patients with the most severe forms of MPS. Since most patients have normally functioning mental activity level, our goal is to provide the patient with access to all functions of a normal keyboard. The other goal of the design is to enhance typing speed and reduce typing errors. A new design of a virtual keyboard with an annular shape is proposed and tested in this research. Based on the two major functional requirements -- text and number/formula inputs, the keyboard is formatted into a design that can easily flip between two modes: the first one focuses on text input, and the second one on numerical/mathematical inputs. To further accelerate the typing speed, the letter prediction and complete word prediction functions are proposed. A series of user tests were conducted on MPS patients using the prototype virtual keyboard.