AIM: To investigate the differences in attainment of developmental milestones 
between young males with Duchenne muscular dystrophy (DMD) and young males from 
the general population.
METHOD: As part of the case-control 4D-DMD study (Detection by Developmental 
Delay in Dutch boys with Duchenne Muscular Dystrophy), data on developmental 
milestones for 76 young males with DMD and 12 414 young males from a control 
group were extracted from the health care records of youth health care services. 
The characteristics of DMD were acquired from questionnaires completed by 
parents. Logistic regression analyses were performed with milestone attainment 
(yes/no) as the dependent variable and DMD (yes/no) as the independent variable, 
with and without adjustment for age at visit.
RESULTS: The mean number of available milestones was 43 (standard deviation 
[SD]=13, range: 1-59) in the DMD group and 40 (SD=15, range: 1-60) in the 
control group. The presence of developmental delay was evident at 2 to 3 months 
of age, with a higher proportion of young males with DMD failing to attain 
milestones of gross/fine motor activity, adaptive behaviour, personal/social 
behaviour, and communication (range age-adjusted odds ratios [ORs]=2.3-4.0, 
p<0.01). Between 12 and 36 months of age, differences in the attainment of 
developmental milestones concerning gross motor activity increased with age 
(range age-adjusted ORs=10.3-532, p<0.001). We also found differences in 
developmental milestones concerning fine motor activity, adaptive behaviour, 
personal/social behaviour, and communication between 12 and 48 months of age 
(range age-adjusted ORs=2.5-9.7, p<0.01).
INTERPRETATION: We found delays in the attainment of motor and non-motor 
milestones in young males with DMD compared to the control group. Such delays 
were already evident a few months after birth. Developmental milestones that 
show a delay in attainment have the potential to aid the earlier diagnosis of 
DMD.