2.1.1.1 Duchenne muscular dystrophy (DMD)

In DMD, affected boys are clinically normal at birth. The onset of clinical features is in early childhood with delayed motor milestones, including delayed independent walking, with a mean age of walking of 18 months, and difficulties in standing up from the floor. The most characteristic clinical features of DMD are general motor delays (42%) and gait problems including persistent toe walking and flat-footedness (30%) [25]. Patients with DMD have a waddling gait and difficulties in climbing stairs, running, jumping, and standing up due to proximal weakness [26]. They rise from a supine position using their arms (Gower maneuver). The boys have hypertrophic and firm calf muscles [27]. The disease is rapidly progressive, at the age of 12 years, most boys being wheelchair bound [25]. Subsequently, the function of upper extremity will be lost, and, by the age of 14–15 years, cardiomyopathy is a common feature [26]; during the teenage years, the patients will require assisted ventilation [27]. Progressive cardiomyopathy and respiratory complications represent the most common causes of death in patients with DMD. Typically, the death occurs by 30 years of age, but currently the life expectancy of these patients has been improved through an improved management of cardiorespiratory function [28].

Intellectual disability can be present in up to 27% of boys with DMD, and 44% of patients have learning disability [28]. Other psychiatric disorders reported in these patients include attention-deficit hyperactivity disorder (ADHD) (32%), anxiety (27%), and autism spectrum disorder (15%) [29].
