A canine BCAN microdeletion associated with episodic falling syndrome

Episodic falling syndrome (EFS) is a canine paroxysmal hypertonicity disorder found in Cavalier King Charles spaniels. Episodes are triggered by exercise, stress or excitement and characterized by progressive hypertonicity throughout the thoracic and pelvic limbs, resulting in a characteristic 'deer-stalking' position and/or collapse. We used a genome-wide association strategy to map the EFS locus to a 3.48 Mb critical interval on canine chromosome 7. By prioritizing candidate genes on the basis of biological plausibility, we found that a 15.7 kb deletion in BCAN, encoding the brain-specific extracellular matrix proteoglycan brevican, is associated with EFS. This represents a compelling causal mutation for EFS, since brevican has an essential role in the formation of perineuronal nets governing synapse stability and nerve conduction velocity. Mapping of the deletion breakpoint enabled the development of Multiplex PCR and Multiplex Ligation-dependent Probe Amplification (MLPA) genotyping tests that can accurately distinguish normal, carrier and affected animals. Wider testing of a larger population of CKCS dogs without a history of EFS from the USA revealed that carriers are extremely common (12.9%). The development of molecular genetic tests for the EFS microdeletion will allow the implementation of directed breeding programs aimed at minimizing the number of animals with EFS and enable confirmatory diagnosis and pharmacotherapy of affected dogs

Pathophysiological Mechanisms of Dominant and Recessive GLRA1 Mutations in Hyperekplexia

Hyperekplexia is a rare, but potentially fatal, neuromotor disorder characterized by exaggerated startle reflexes and hypertonia in response to sudden, unexpected auditory or tactile stimuli. This disorder is primarily caused by inherited mutations in the genes encoding the glycine receptor (GlyR) alpha 1 subunit (GLRA1) and the presynaptic glycine transporter GlyT2 (SLC6A5). In this study, systematic DNA sequencing of GLRA1 in 88 new unrelated human hyperekplexia patients revealed 19 sequence variants in 30 index cases, of which 21 cases were inherited in recessive or compound heterozygote modes. This indicates that recessive hyperekplexia is far more prevalent than previous estimates. From the 19 GLRA1 sequence variants, we have investigated the functional effects of 11 novel and 2 recurrent mutations. The expression levels and functional properties of these hyperekplexia mutants were analyzed using a high-content imaging system and patch-clamp electrophysiology. When expressed in HEK293 cells, either as homomeric alpha 1 or heteromeric alpha 1 beta GlyRs, subcellular localization defects were the major mechanism underlying recessive mutations. However, mutants without trafficking defects typically showed alterations in the glycine sensitivity suggestive of disrupted receptor function. This study also reports the first hyperekplexia mutation associated with a GlyR leak conductance, suggesting tonic channel opening as a new mechanism in neuronal ligand-gated ion channels

Co-transplantation of mesenchymal stem cells might mitigate acute GvHD without abrogating graftversus- tumour alloreactivity after allogeneic transplantation with non-myeloablative conditioning

peer reviewedBackground: Results of nonmyeloablative HCT in pts with HLA-mismatched donors have been disappointing due to high incidence of graft rejection and severe acute GVHD. Recent studies have suggested that infusion of mesenchymal stem cells (MSC) the day of HCT might promote engraftment and prevent acute GVHD after myeloablative allogeneic HCT. However, some studies suggested that MSC co-infusion might abrogate graft-versus-host alloreactivity and graft-versus-tumor effects. This prompted us to investigate whether MSC infusion a few hours before HCT could allow nonmyeloablative HCT from HLA-mismatched donors to be performed safely (i.e. with a 100-day incidence of nonrelapse mortality < 35%). Methods: 20 patients with hematological malignancies were given MSC (1-2 x 10E6 cells/kg) from third party donors a few hours before PBSC from HLA-mismatched unrelated donors, after conditioning with 2 Gy TBI and fl udarabine 90 mg/m. Postgrafting immunosuppression included tacrolimus (day -3 to +180; tapered by day +365) and mycophenolate mofetil (tid days 0 to +42). HLA-compatibility was assessed at the HLA-A, -B, -C, -DRBI and DQBI loci: 13 pairs were mismatched for at least one HLA class I antigen (including 4 pairs who were also mismatched for 1 HLA-class II antigens (n=3) or 1 HLA-class I allele (n=1)), 1 pair was mismatched for 2 HLA class II alleles, while 6 pairs were mismatched for a single HLA class I (n=3) or HLA class II (n=3) alleles. Results: Median follow-up for surviving patients was 288 (range, 76-571) days. One patient with secondary AML had primary graft rejection, while the remaining 19 patients had sustained engraftment. Median donor T-cell chimerism levels on days 28, 100, 180 and 365 after HCT were 90%, 98%, 96%, and 98%, respectively. Grade II, III and IV acute GVHD were seen in 5, 2 and 1 patients, respectively, while 7 experienced NIH moderate/severe chronic GVHD. Three of 7 patients with measurable disease at transplantation achieved complete remission on days 41, 104 and 353 after HCT. Two patients died of nonrelapse causes on days 74 and 114 after HCT, while 3 died of disease progression. Projected 1-yr overall and progressionfree survivals were 77% and 61%, respectively. Conclusions: HLA-mismatched nonmyeloablative HCT with MSC co-infusion appeared to be safe, with MSC co-infusion possibly mitigating graft-versus-host alloreactivity without abrogating graft-versus-tumor effects. Survival is encouraging

Clinical Characteristics and Therapeutic Responses in Patients with Germ-Line AIP Mutations and Pituitary Adenomas: An International Collaborative Study

Context: AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. Objective: The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. Design: This study was an international, multicenter, retrospective case collection/database analysis. Setting: The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. Patients: Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. Results: The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n = 13), nonsecreting adenomas (n = 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P = 0.00026), with higher GH levels (P = 0.00068), more frequent extension (P = 0.018) and prolactin cosecretion (P = 0.00023), and occurred 2 decades before controls (P < 0.000001). Gigantism was more common in the AIPmut group (P < 0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P = 0.00069) and had lower decreases in GH (P = 0.00037) and IGF-I (P = 0.028) and less tumor shrinkage with somatostatin analogs (P < 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. Conclusions: AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility. (J Clin Endocrinol Metab 95: E373-E383, 2010

Clinical characteristics and therapeutic responses in patients with germ-line AIP mutations and pituitary adenomas: an international collaborative study.

Context: AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. Objective: The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. Design: This study was an international, multicenter, retrospective case collection/database analysis. Setting: The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. Patients: Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. Results: The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n 13), nonsecreting adenomas (n 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P 0.00026), with higher GH levels (P 0.00068), more frequent extension (P 0.018) and prolactin cosecretion (P 0.00023), and occurred 2 decades before controls (P0.000001). Gigantism was more common in the AIPmut group (P0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P 0.00069) and had lower decreases in GH (P 0.00037) and IGF-I (P 0.028) and less tumor shrinkage with somatostatin analogs (P 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. Conclusions: AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility