Female carriers of Duchenne muscular dystrophy

The disease is inherited in an X-linked manner although up to 30% of cases represent new mutations. The gene for Duchenne muscular dystrophy is the dystrophin locus at Xp21.

• occurs in approximately 1 in 3500 male births, and in about 1 in 50 000 000 female births (1)
  • a female only develops DMD if both of her X chromosomes have faults in their dystrophin genes
  • those very rare females who have DMD are believed to either carry mutant genes on both X chromosomes, or have an inactivated healthy X chromosome (1)
• females with a mutant X chromosome will not have DMD, but they will be carriers of the disorder
• a small number of female carriers can develop muscle symptoms, such as myalgia, cramps, or weakness, and learning or behavioural problems (2,3,4,5)
• female carriers are also at risk of cardiovascular problems - regular cardiovascular monitoring is recommended
• early counselling for family planning (including discussion about possible pre-implantation or prenatal genetic testing) should be offered to women and girls of reproductive age
  • non-carrier mothers of sons with DMD still have a slightly higher risk of having another affected child compared with the general population and therefore should be offered counselling (4)

Reference:

1. Yilmaz O et al. Prednisolone therapy in Duchenne muscular dystrophy prolongs ambulation and prevents scoliosis. Eur J Neurol. 2004 Aug;11(8):541-4.
2. Webb CL. Parents' perspectives on coping with Duchenne muscular dystrophy. Child Care Health Dev. 2005 Jul;31(4):385-96.
3. Rodger S et al. Adult care for Duchenne muscular dystrophy in the UK. J Neurol. 2015; 262(3): 629–6
4. Fox H et al. Duchenne muscular dystrophy. BMJ 2020;368:l7012
5. Lisak RP, Truong DD, Carroll W, Bhidayasiri R (2011). International Neurology. Wiley. p. 222. ISBN 9781444317015.