Duchenne type muscular dystrophy and consanguinity: difficulties in pedigree analysis

Area of Science:

• Genetics
• Neuromuscular Disorders
• Pediatrics

Background:

• Duchenne muscular dystrophy (DMD) is a severe X-linked genetic disorder.
• Early diagnosis and understanding of inheritance patterns are crucial for genetic counseling and management.
• Consanguinity in parents can increase the risk of recessive genetic conditions.

Observation:

• A 2-year-old girl presented with clinical, electromyographic, laboratory, and pathological findings consistent with Duchenne muscular dystrophy.
• The proband's parents were first cousins, indicating consanguinity.
• Affected maternal relatives, including a brother and nephew, were noted, alongside a mother with very high plasma creatine kinase (CK) levels.

Findings:

• Karyotype analysis of the proband revealed morphologically normal X chromosomes.
• The mother exhibited extremely high plasma CK levels, typical of female carriers of DMD.
• The family pedigree suggests a potential deviation from typical X-linked recessive inheritance for DMD.

Implications:

• This case highlights the possibility of atypical inheritance patterns or genetic modifiers in Duchenne muscular dystrophy.
• Further investigation into the genetic mechanisms underlying this presentation is warranted.
• Understanding such cases can refine genetic counseling for families with consanguinity and a history of neuromuscular disorders.