Utilization of Targeted RNA-Seq for the Resolution of Variant Pathogenicity and Enhancement of Diagnostic Yield in Dysferlinopathy.

For inherited diseases, obtaining a definitive diagnosis is critical for proper disease management, family planning, and participation in clinical trials. This can be challenging for dysferlinopathy due to the significant clinical overlap between the 30+ subtypes of limb-girdle muscular dystrophy (LGMD) and the large number of variants of unknown significance (VUSs) that are identified in the dysferlin gene, DYSF. We performed targeted RNA-Seq using a custom gene-panel in 77 individuals with a clinical/genetic suspicion of dysferlinopathy and evaluated all 111 identified DYSF variants according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines. This evaluation identified 11 novel DYSF variants and allowed for the classification of 87 DYSF variants as pathogenic/likely pathogenic, 8 likely benign, while 16 variants remained VUSs. By the end of the study, 60 of the 77 cases had a definitive diagnosis of dysferlinopathy, which was a 47% increase in diagnostic yield over the rate at study onset. This data shows the ability of RNA-Seq to assist in variant pathogenicity classification and diagnosis of dysferlinopathy and is, therefore, a type of analysis that should be considered when DNA-based genetic analysis is not sufficient to provide a definitive diagnosis.

Patient reported pregnancy and birth outcomes in genetic neuromuscular diseases.

Pregnancy and birth in women with neuromuscular conditions has been associated with more rapid disease progression and obstetric complications. This study assessed the impact of functional status and specific diagnosis on patient reported pregnancy and birth outcomes in 26 genetic neuromuscular diseases. Pregnancy and birth outcomes were collected through electronic patient questionnaires and analysed by mobility group and diagnosis. Free text responses were grouped into themes. 721 pregnancies were reported by 305 women. Miscarriage (21% of pregnancies), caesarean delivery (38% of births) and instrumental vaginal delivery (19% of births) were all more frequent in respondents than in the general population (p<0.05), and were more common in those who were non-ambulant at conception than other mobility levels (p <0.05). Falls occurred during 42% of pregnancies and a deterioration in muscle strength during 43%. There was not an increased incidence of maternal complications, apart from maternal hypertension which was more common in limb girdle muscular dystrophy 2A/R1 (35%) and myotonic dystrophy (24%). Patients offered specific practical advice to prospective mothers. Women with neuromuscular conditions have a more complex antenatal and perinatal course than unaffected women. Prenatal counselling, specialist obstetric review and additional occupational therapy support should be considered.