A dominant gain-of-function mutation in universal tyrosine kinase <i>SRC </i>causes thrombocytopenia, myelofibrosis, bleeding, and bone pathologies

The Src family kinase (SFK)member SRC is amajor target in drug development because it is activated in many human cancers, yet deleterious SRC germline mutations have not been reported. We used genome sequencing and Human Phenotype Ontology patient coding to identify a gain-of-function mutation in SRC causing thrombocytopenia, myelofibrosis, bleeding, and bone pathologies in nine cases. Modeling of the E527K substitution predicts loss of SRC's self-inhibitory capacity, whichwe confirmedwith in vitro studies showing increased SRC kinase activity and enhanced Tyr419 phosphorylation in COS-7 cells overexpressing E527K SRC. The active form of SRC predominates in patients' platelets, resulting in enhanced overall tyrosine phosphorylation. Patientswith myelofibrosis have hypercellular bone marrow with trilineage dysplasia, and their stem cells grown in vitro form more myeloid and megakaryocyte (MK) colonies than control cells. These MKs generate platelets that are dysmorphic, low in number, highly variable in size, and have a paucity of a-granules. Overactive SRC in patient-derived MKs causes a reduction in proplatelet formation, which can be rescued by SRC kinase inhibition. Stem cells transduced with lentiviral E527K SRC formMKs with a similar defect and enhanced tyrosine phosphorylation levels. Patient-derived and E527K-transduced MKs show Y419 SRC- positive stained podosomes that induce altered actin organization. Expression of mutated src in zebrafish recapitulates patients' blood and bone phenotypes. Similar studies of platelets andMKs may reveal the mechanism underlying the severe bleeding frequently observed in cancer patients treated with next-generation SFK inhibitors. © 2016 by the American Association for the Advancement of Science; all rights reserved

Upper limb evaluation and one-year follow up of non-ambulant patients with spinal muscular atrophy: an observational multicenter trial.

Assessment of the upper limb strength in non-ambulant neuromuscular patients remains challenging. Although potential outcome measures have been reported, longitudinal data demonstrating sensitivity to clinical evolution in spinal muscular atrophy patients are critically lacking. Our study recruited 23 non-ambulant patients, 16 patients (males/females = 6/10; median age 15.4 years with a range from 10.7 to 31.1 years) with spinal muscular atrophy type II and 7 patients (males/females = 2/5; median age 19.9 years with a range from 8.3 to 29.9 years) with type III. The Brooke functional score was on median 3 with a range from 2 to 6. The average total vital capacity was 46%, and seven patients required non-invasive ventilation at night. Patients were assessed at baseline, 6 months, and 1 year using the Motor Function Measure and innovative devices MyoGrip, MyoPinch, and MoviPlate, which assess handgrip strength, key pinch strength, and hand/finger extension-flexion function, respectively. The study demonstrated the feasibility and reliability of these measures for all patients, and sensitivity to negative changes after the age of 14 years. The younger patients showed an increase of the distal force in the follow-up period. The distal force measurements and function were correlated to different functional scales. These data represent an important step in the process of validating these devices as potential outcome measures for future clinical trials

Upper Limb Strength and Function Changes during a One-Year Follow-Up in Non-Ambulant Patients with Duchenne Muscular Dystrophy: An Observational Multicenter Trial

International audienceBACKGROUND: Upper limb evaluation of patients with Duchenne Muscular Dystrophy is crucially important to evaluations of efficacy of new treatments in non-ambulant patients. In patients who have lost ambulation, there are few validated and informative outcome measures. In addition, longitudinal data demonstrating sensitivity to clinical evolution of outcome measures over short-term periods are lacking.METHODS: We report here the results of a one-year multicenter study using specifically designed tools to assess grip, pinch strength, and hand function in wheelchair-bound patients. Our study assessed 53 non-ambulant patients with Duchenne muscular dystrophy aged 17.1 ± 4.8 years (range: 9 - 28.1 years). The average Brooke functional score of these patients was 4.6 ± 1.1. The average forced vital capacity was 44.5% predicted and 19 patients used non-invasive ventilation. Patients were assessed at baseline, 6 months, and one year using the Motor Function Measure and innovative devices (namely the MyoSet composed of MyoGrip, MyoPinch, and MoviPlate).RESULTS: Our study confirmed preliminary data previously reported regarding feasibility of use and of reliability of the MyoSet and the correlation at baseline between distal strength and clinical outcomes such as FVC, Brooke score, age, and duration since loss of ambulation. A significant correlation was observed between the distal upper limb strength and clinical variables. The sensitive dynamometers (MyoGrip and MyoPinch) and MoviPlate captured a 12-month change in non-ambulant Duchenne muscular dystrophy patients of all ages.BACKGROUND: ClinicalTrials.gov NCT00993161 NCT00993161

Correlation between MyoSets at baseline on dominant (D) and non-dominant (ND) sides, clinical and motor function parameters.

<p>* p-value < 0.05,</p><p>** p-value < 0.01.</p><p>Correlation between MyoSets at baseline on dominant (D) and non-dominant (ND) sides, clinical and motor function parameters.</p

Reliability parameters for SMA patients.

<p>** p-value < 0.01.</p><p>Reliability parameters for SMA patients.</p

Follow-up MyoSets data and MFM scores for all SMA patients.

<p>Data at 6 months and at one year for all SMA patients for (A) grip, (B) pinch, and (C) MoviPlate on the dominant (D) and non-dominant (ND) sides and for (D) MFM-D3 and MFM-Total scores. SMA type II for whom data at 6 months and one year are lacking are marked with orange triangles; for type II patients for whom data were obtained at both time points, the orange interrupted line represents their evolution. The purple solid lines represent the evolution of SMA type 3 patients. The age of 14 is marked with a vertical dotted line.</p

MoviPlate correlations with grip and pinch strength.

<p>Correlations at baseline between the MoviPlate scores and grip and pinch strength for all SMA patients for the non-dominant hands (dark dots) and the dominant hands (clear dots).</p

Comparison of strength and motor function between the two groups on dominant (D) and non-dominant (ND) sides.

<p>* p-value < 0.05 for group effect,</p><p>** p-value < 0.01 for group effect.</p><p>Comparison of strength and motor function between the two groups on dominant (D) and non-dominant (ND) sides.</p

Reliability test.

<p>Reliability of test and retest sessions for (A) grip, (B) pinch, and (C) MoviPlate for all SMA patients for the non-dominant hands (dark dots) and the dominant hands (clear dots).</p

Clinical and functional comparison between the SMA type II and III groups.

<p>* p-value < 0.05 for group effect,</p><p>** p-value < 0.01 for group effect.</p><p>Clinical and functional comparison between the SMA type II and III groups.</p