Decoding Neuromuscular Disorders Using Phenotypic Clusters Obtained From Co-Occurrence Networks

Co-occurrence of CAPN3 homozygous mutation and CCTG expansion in the CNBP gene in a patient with muscular dystrophy

Purpose

Muscular dystrophy is a group of heterogeneous diseases causing progressive muscle weakness and atrophy. Many types have been defined, including Duchenne/Becker, myotonic, limb-girdle, congenital, and facioscapulohumeral muscular dystrophies. This study aims to present the first patient with both a homozygous CAPN3 mutation and a CCTG expansion in the CNBP gene, which suggests the co-occurrence of two diseases in a single patient.

Case description

Homozygous pathogenic variant c.550delA (p.Thr184ArgfsTer36) in the CAPN3 gene, as well as a heterozygous expansion of a CCTG repeat of the CNBP gene, were identified in a single patient. Segregation analysis showed both maternal and paternal heterozygous carriers for CAPN3 mutation, and a maternally inherited CNBP expansion.

Comment

In general, the co-occurrence of two diseases in a single patient is considered as uncommon, although possible, and therefore it should be taken into consideration in the populations with a relatively high prevalence of myotonic dystrophy type 2.

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Network and systemic approaches to studying human pathologies are helping us to gain insight into the molecular mechanisms of and potential therapeutic interventions for human diseases, especially for complex diseases where large numbers of genes are involved. The complex human pathological landscape is traditionally partitioned into discrete “diseases”; however, that partition is sometimes problematic, as diseases are highly heterogeneous and can differ greatly from one patient to another. Moreover, for many pathological states, the set of symptoms (phenotypes) manifested by the patient is not enough to diagnose a particular disease. On the contrary, phenotypes, by definition, are directly observable and can be closer to the molecular basis of the pathology. These clinical phenotypes are also important for personalised medicine, as they can help stratify patients and design personalised interventions. For these reasons, network and systemic approaches to pathologies are gradually incorporating phenotypic information. This review covers the current landscape of phenotype-centred network approaches to study different aspects of human diseases.

Hypermobile Ehlers-Danlos syndrome: A review and a critical appraisal of published genetic research to date

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