Mutation spectrum in the large GTPase dynamin 2, and genotype-phenotype correlation in autosomal dominant centronuclear myopathy.

Centronuclear myopathy (CNM) is a genetically heterogeneous disorder associated with general skeletal muscle weakness, type I fiber predominance and atrophy, and abnormally centralized nuclei. Autosomal dominant CNM is due to mutations in the large GTPase dynamin 2 (DNM2), a mechanochemical enzyme regulating cytoskeleton and membrane trafficking in cells. To date, 40 families with CNM-related DNM2 mutations have been described, and here we report 60 additional families encompassing a broad genotypic and phenotypic spectrum.

A multicenter study of the frequency and distribution of GJB2 and GJB6 mutations in a large North American cohort.

Purpose: The aim of the study was to determine the actual GJB2 and GJB6 mutation frequencies in North America after several years of generalized testing for autosomal recessive nonsyndromic sensorineural hearing loss to help guide diagnostic testing algorithms, especially in light of molecular diagnostic follow-up to universal newborn hearing screening.

Methods: Mutation types, frequencies, ethnic distributions, and genotype-phenotype correlations for GJB2 and GJB6 were assessed in a very large North American cohort.

Results: GJB2 variants were identified in 1796 (24.

Mosaicism del(22)(q11.2q11.2)/dup(22)(q11.2q11.2) in a patient with features of 22q11.2 deletion syndrome.

The chromosome 22q11 region is prone to rearrangements, including deletions and duplications, due to the presence of multiple low copy repeats (LCRs). DiGeorge/velo-cardio-facial syndrome is the most common microdeletion syndrome with more than 90% of patients having a common 3-Mb deletion of 22q11.2 secondary to non-homologous recombination of flanking LCRs.

Two cases further delineating the Sakoda complex.

Sakoda complex consists of sphenoethmoidal encephalomeningocele, agenesis of the corpus callosum, and cleft lip and/or palate. Associated abnormalities include optic disc dysplasia, microphthalmia, cortical dysgenesis, mental retardation and epilepsy. The etiology remains unknown.