Quiz Form

Question Date: 10/10/2023

Question: Which of these statements is not true regarding Facioscapulohumeral dystrophy?

Options:

• It is caused by expansion of D4Z4 repeats
• Asymmetric weakness is common
• Beevors sign is almost exclusively seen in FSHD
• Genetic anticipation is seen

Correct Answer: It is caused by expansion of D4Z4 repeats

Explaination: Facioscapulohumeral dystrophy is a common autosomal dominant muscular dystrophy. Genetic anticipation with more severe illness in subsequent generations is common. The genetics of this disorder is complex. It is thought to arise from expression of a normally silenced DUX4 gene on chromosome 4q35. It is suppressed by methylation of a DNA sequence near the gene known as D4Z4. Normally more than 10 repeats of D4Z4 are present. In FSHD, deletion in D4Z4 sequence leads to smaller number of repeats (<10) and hypomethylation leading to expression. Facial and scapular weakness are characteristic. Another hallmark is the marked asymmetry of weakness leading to doubts in diagnosis. The Beevor sign results from weakness of lower abdominal muscles so that when the supine patient lifts the head, the umbilicus is pulled upward. It is not seen in other muscular dystrophies

Reference: Doughty C T, Amato A A. Disorders of Skeletal Muscle. Bradley and Daroffs Neurology in Clinical Practice. 2022. Ch 1091978