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Published on: July 1, 2020
Clinical variability and molecular diagnosis in a four-generation family with X-linked Emery-Dreifuss muscular
N Canki-Klain1, D Récan, D Milicić
1Division of Neurogenetics, Department of Neurology, Zagreb University School of Medicine and Hospital Center, Kispaticeva 12, 10000 Zagreb, Croatia. nina.canki-klain@zg.tel.hr
Insights
Clinical variability in X-linked Emery-Dreifuss muscular dystrophy (X-EDMD) with cardiac involvement is significant, even with a novel STA gene mutation. This study highlights the importance of early cardiac monitoring in affected families.
Area of Science:
- Genetics
- Cardiology
- Neuromuscular Disorders
Background:
- X-linked Emery-Dreifuss muscular dystrophy (X-EDMD) is a rare genetic disorder.
- Cardiac involvement is a significant feature of X-EDMD, often leading to severe complications.
- The STA gene mutation's role in X-EDMD variability requires further investigation.
Purpose of the Study:
- To investigate the clinical variability of X-linked Emery-Dreifuss muscular dystrophy (X-EDMD) in a four-generation family.
- To describe cardiac involvement associated with a novel STA gene mutation.
- To highlight the diagnostic and preventive implications of intra-familial variability.
Main Methods:
- Clinical data collection from four affected males and one female carrier.
- Western blot analysis of emerin.
- Sequencing of the emerin gene.
Main Results:
- A novel thymine insertion (417 ins T) in the STA gene caused a frameshift and absence of functional protein in one patient.
- Significant cardiac abnormalities, including various arrhythmias, were observed in unaffected dizygotic twin-nephews.
- Proband showed early-onset muscle wasting and required pacemaker implantation at age 27, contrasting with other family members.
Conclusions:
- Striking intra-familial variability in cardiac involvement associated with the 417 ins T mutation was observed.
- Early diagnostic and preventive strategies are crucial for X-EDMD patients.
- Genetic and environmental factors likely contribute to the clinical presentation of X-EDMD.
Aim:
To describe the clinical variability of X-linked Emery-Dreifuss muscular dystrophy (X-EDMD) with cardiac involvement in a four-generation family with a novel mutation in the STA gene.
Methods:
Clinical data were provided for 4 affected males and a female carrier. The Western blot analysis of emerin was performed on lymphoblastoid cell lines and followed by sequencing of the emerin gene.
Results:
A thymine insertion at nucleotide 417 in exon 2, resulting in a frameshift with a premature stop codon at position 62 and absence of functional protein, was found in one of the three available patients. In ten-year-old proband's dizygotic twin-nephews the intermittent first-degree A-V block, atrial and ventricular ectopy, atrial runs, and exit sinus block were found, although the echocardiographic findings were normal. One of the twins also had short episodes of atrial fibrillation, idioventricular rhythm, and junctional rhythm.
Conclusion:
Cardiac abnormalities in the proband's ten-year-old dizygotic twins without evident clinical features suggestive of EDMD were remarkable in contrast to the oldest patient in the family, who lived to the age of 63 without a pacemaker, and to the proband who had a very early onset of muscle wasting and weakness, and a pacemaker implantation at the age of 27. This striking intra-familial variability in cardiac involvement associated with specific null mutation (417 ins T) has practical early diagnostic and possibly preventive implications. It also points at genetic and environmental factors as causes of clinical features in X-EDMD.
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