Next-generation sequencing approach to hyperCKemia: A 2-year cohort study.

OBJECTIVE: Next-generation sequencing (NGS) was applied in molecularly undiagnosed asymptomatic or paucisymptomatic hyperCKemia to investigate whether this technique might allow detection of the genetic basis of the condition. METHODS: Sixty-six patients with undiagnosed asymptomatic or paucisymptomatic hyperCKemia, referred to tertiary neuromuscular centers over an approximately 2-year period, were analyzed using a customized, targeted sequencing panel able to investigate the coding exons and flanking intronic regions of 78 genes associated with limb-girdle muscular dystrophies, rhabdomyolysis, and metabolic and distal myopathies. RESULTS: A molecular diagnosis was reached in 33 cases, corresponding to a positive diagnostic yield of 50%. Variants of unknown significance were found in 17 patients (26%), whereas 16 cases (24%) remained molecularly undefined. The major features of the diagnosed cases were mild proximal muscle weakness (found in 27%) and myalgia (in 24%). Fourteen patients with a molecular diagnosis and mild myopathic features on muscle biopsy remained asymptomatic at a 24-month follow-up. CONCLUSIONS: This study of patients with undiagnosed hyperCKemia, highlighting the advantages of NGS used as a first-tier diagnostic approach in genetically heterogeneous conditions, illustrates the ongoing evolution of molecular diagnosis in the field of clinical neurology. Isolated hyperCKemia can be the sole feature alerting to a progressive muscular disorder requiring careful surveillance.

Spastic paraplegia with thin corpus callosum: description of 20 new families, refinement of the SPG11 locus, candidate gene analysis and evidence of genetic heterogeneity.

We studied 20 Mediterranean families (40 patients) with autosomal recessive hereditary spastic paraplegia and thin corpus callosum (ARHSP-TCC, MIM 604360) to characterize their clinical and genetic features. In six families (17 patients) of Algerian Italian, Moroccan, and Portuguese ancestry, we found data consistent with linkage to the SPG11 locus on chromosome 15q13-15, whereas, in four families (nine patients of Italian, French, and Portuguese ancestry) linkage to the SPG11 locus could firmly be excluded, reinforcing the notion that ARHSP-TCC is genetically heterogeneous. Patients from linked and unlinked families could not be distinguished on the basis of clinical features alone. In SPG11-linked kindred, haplotype reconstruction allowed significant refinement to 6 cM, of the minimal chromosomal interval, but analysis of two genes (MAP1A and SEMA6D) in this region did not identify causative mutations. Our findings suggest that ARHSP-TCC is the most frequent form of ARHSP in Mediterranean countries and that it is particularly frequent in Italy.

A new missense mutation in caveolin-3 gene causes rippling muscle disease.

Mutations of the Cav-3 gene are associated with distinct, sometimes overlapping muscle disease phenotypes. We report a new Italian family with autosomal dominant rippling muscle disease. Immunocytochemical analysis of muscle showed a deficit of caveolin-3 protein and molecular genetic analysis showed a novel mutation of the Cav-3 gene.

Six novel mutations of the RUNX2 gene in Italian patients with cleidocranial dysplasia.

We report clinical and molecular findings in 14 patients with cleidocranial dysplasia (CCD), a well defined skeletal disorder with characteristic clinical findings and autosomal dominant inheritance. We identified ten heterozygous base changes in the RUNX2 gene, including six novel mutations [c.522insA, c.389G>A (W130X), c.662T>G (V221G), IVS2+T>A, c.1111_1129del19, and c.873_874delCA]. We did not establish a clear correlation between clinical features and genotype, the phenotypes of all patients analyzed falling within the range of variation described in CCD without an effect related to the length of the predicted protein. In two cases, however, a limb-girdle myopathy affecting the shoulder muscles was also identified. Our data add new variants to the repertoire of RUNX2 mutations in CCD.