A novel gain-of-function mutation in ORAI1 causes late-onset tubular aggregate myopathy and congenital miosis

We present three members of an Italian family affected by tubular aggregate myopathy (TAM) and congenital miosis harboring a novel missense mutation in ORAI1. All patients had a mild, late onset TAM revealed by asymptomatic creatine kinase (CK) elevation and congenital miosis consistent with a Stormorken-like Syndrome, in the absence of thrombocytopathy. Muscle biopsies showed classical histological findings but ultrastructural analysis revealed atypical tubular aggregates (TAs). The whole body muscle magnetic resonance imaging (MRI) showed a similar pattern of muscle involvement that correlated with clinical severity. The lower limbs were more severely affected than the scapular girdle, and thighs were more affected than legs. Molecular analysis revealed a novel c.290C>G (p.S97C) mutation in ORAI1 in all affected patients. Functional assays in both human embryonic kidney (HEK) cells and myotubes showed an increased rate of Ca²⁺ entry due to a constitutive activation of the CRAC channel, consistent with a 'gain-of-function' mutation. In conclusion, we describe an Italian family harboring a novel heterozygous c.290C>G (p.S97C) mutation in ORAI1 causing a mild- and late-onset TAM and congenital miosis via constitutive activation of the CRAC channel. Our findings extend the clinical and genetic spectrum of the ORAI1-related TAM.

Myotonic dystrophy type 1 and de novo FSHD mutation double trouble: a clinical and muscle MRI study

Here we describe the first case of myotonic dystrophy type 1 (DM1) associated with facio-scapulo-humeral dystrophy (FSHD). From a clinical point of view, the patient displayed a pattern of muscle involvement reminiscent of both disorders, including hand-grip myotonia, facial, axial and distal limbs muscle weakness as well as a bilateral winged scapula associated with atrophy of the pectoralis major muscle and lumbar lordosis; pelvic muscles were mostly spared. An extensive muscle MRI assessment including neck, shoulder, abdominal, pelvic and lower limb muscles documented radiological features typical of DM1 and FSDH. Molecular genetic studies confirmed that the proband carried both a pathologically expanded DMPK allele, inherited from his father, and a de novo shortened D4Z4 repeat fragment at 4q35 locus.

Muscle MRI in female carriers of dystrophinopathy

BACKGROUND AND PURPOSE

Duchenne muscular dystrophy carriers represent a rare condition that needs to be recognized because of the possible implications for prenatal diagnosis. Muscle biopsy is currently the diagnostic instrument of choice in sporadic patients. We wanted to verify whether muscle magnetic resonance imaging (MRI) could identify a pattern of involvement suggestive of this condition and whether it was similar to that reported in Duchenne and Becker muscular dystrophy.

METHODS

Evaluation of pelvic and lower limb MRI scans of 12 dystrophinopathy carriers was performed.

RESULTS

We found a frequent involvement of the quadratus femoris, gluteus maximus and medius, biceps femoris long head, adductor magnus, vasti and paraspinal muscles, whilst the popliteus, iliopsoas, recti abdominis, sartorius, and gracilis were relatively spared. Asymmetry was a major feature on MRI; it could be detected significantly more often than with sole clinical examination and even in patients without weakness.

CONCLUSIONS

The pattern we describe here is similar to that reported in Duchenne and Becker muscular dystrophy, although asymmetry represents a major distinctive feature. Muscle MRI was more sensitive than clinical examination for detecting single muscle involvement and asymmetry. Further studies are needed to verify the consistency of this pattern in larger cohorts and to assess whether muscle MRI can improve diagnostic accuracy in carriers with normal dystrophin staining on muscle biopsy.

Magnetic resonance imaging in the diagnosis of melanoma: in vivo preliminary studies with dynamic contrast-enhanced subtraction

The aim of this study was to analyse the potential of fast dynamic subtraction magnetic resonance (MR) imaging in differentiating in vivo melanomas from benign melanocytic lesions. Dynamic MR imaging was performed after intravenous administration of gadopentetate dimeglumine (Gd-DTPA) in 18 patients with melanocytic skin lesions. Using a post-processing algorithm, time-signal intensity curves were obtained for the lesions and classified according to their shapes as type I (steady enhancement increase), type II (plateau of signal intensity) or type III (wash-out of signal intensity). Other parameters evaluated for their potential to differentiate melanomas from benign lesions were the enhancement rate (percentage of signal intensity increase) in the first minute after Gd-DTPA administration, the peak value of the enhancement rate, and the wash-out slope. The pigmented lesions were then surgically excised and the MR results compared with the histological assessment. In melanomas, the mean value of the enhancement rate in the first minute was 611%, whereas in benign lesions it was 131% (P = 0.001). The distribution of curve types was also different: seven of the nine naevi showed type I curves, while eight of the nine melanomas displayed a type III curve. In addition, distinctive wash-out dynamics were observed: the enhancement rate began to decrease between the first and third minutes for melanomas, but continued to increase until the sixth minute for naevi (P = 0.000). These findings, which are most likely related to the neoangiogenesis present in melanomas, indicate that dynamic MR imaging can be helpful in the differential diagnosis of pigmented skin lesions.