Ethanol and/or radiofrequency ablation to treat venolymphatic malformations that manifest as a bulging mass in the head and neck

AIM

To evaluate the efficacy of ultrasound (US)-guided ethanol ablation (EA) and radiofrequency ablation (RFA) for treating venolymphatic malformations (VLM) of the head and neck.

MATERIALS AND METHODS

US-guided EA and/or RFA were performed on 17 patients with VLM of the head and neck. Computed tomography (CT) or magnetic resonance imaging (MRI) was used to locate the cranial nerves and salivary gland ducts that were close to targets, and these were avoided during the procedures. Treatment response was assessed using volume reduction and cosmetic grading scoring.

RESULTS

Nine VLMs were located close to the functional structures: Stensen's duct (n=3), cranial nerve branch (n=3), or both (n=3). All patients demonstrated >50% volume reduction, except one patient with a microcystic lymphatic malformation that was abutting the facial nerve. Median cosmetic grading scores improved from 4 to 1 (p<0.001).

CONCLUSION

US-guided EA and/or RFA are effective and safe treatment methods in patients with VLMs of the head and neck. Treatment selection of EA and/or RFA could be performed based on the composition of VLMs as assessed at CT and MRI.

Trabecular bone score as a skeletal fragility index in acromegaly patients

SUMMARY

Lumbar spine trabecular bone score (TBS) was significantly decreased in active acromegaly patients. TBS may be useful to assess the skeletal fragility in acromegaly in which bone mineral density (BMD) is not sufficient to represent bone strength and explain the high incidence of fragility fractures in acromegaly patients.

INTRODUCTION

Although the data on BMD are controversial, patients with acromegaly have an increased risk of fragility fracture. We examined the lumbar spine TBS to explain the skeletal deterioration in acromegaly patients.

METHODS

We included 14 men and 19 women acromegaly patients who underwent dual-energy X-ray absorptiometry at the time of diagnosis from 2000 to 2014 at Seoul National University Hospital. Ninety-nine age-, sex- and body mass index-matched controls were recruited. Biochemical parameters, lumbar spine TBS, and BMD at all sites were measured. Gonadal status was evaluated at diagnosis.

RESULTS

Lumbar spine TBS was lower in acromegaly patients than in controls in both genders (1.345 ± 0.121 vs. 1.427 ± 0.087, P = 0.005 in men; 1.356 ± 0.082 vs. 1.431 ± 0.071, P = 0.001 in women). In contrast, BMD at all sites did not differ between the two groups. Hypogonadal acromegaly patients (men, n = 9; women, n = 12) had lower TBS values compared with controls both in men and women (all P < 0.05), although BMD at all sites were similar for the two groups. In eugonadal acromegaly patients, lumbar spine TBS was lower than in women controls only (P = 0.041).

CONCLUSIONS

Skeletal microarchitecture was deteriorated in acromegaly patients as assessed by TBS, which seems to be a consequence of growth hormone excess as well as hypogonadism, especially in women.

Novel strategy for a bispecific antibody: induction of dual target internalization and degradation

Activation of the extensive cross-talk among the receptor tyrosine kinases (RTKs), particularly ErbB family-Met cross-talk, has emerged as a likely source of drug resistance. Notwithstanding brilliant successes were attained while using small-molecule inhibitors or antibody therapeutics against specific RTKs in multiple cancers over recent decades, a high recurrence rate remains unsolved in patients treated with these targeted inhibitors. It is well aligned with multifaceted properties of cancer and cross-talk and convergence of signaling pathways of RTKs. Thereby many therapeutic interventions have been actively developed to overcome inherent or acquired resistance. To date, no bispecific antibody (BsAb) showed complete depletion of dual RTKs from the plasma membrane and efficient dual degradation. In this manuscript, we report the first findings of a target-specific dual internalization and degradation of membrane RTKs induced by designed BsAbs based on the internalizing monoclonal antibodies and the therapeutic values of these BsAbs. Leveraging the anti-Met mAb able to internalize and degrade by a unique mechanism, we generated the BsAbs for Met/epidermal growth factor receptor (EGFR) and Met/HER2 to induce an efficient EGFR or HER2 internalization and degradation in the presence of Met that is frequently overexpressed in the invasive tumors and involved in the resistance against EGFR- or HER2-targeted therapies. We found that Met/EGFR BsAb ME22S induces dissociation of the Met-EGFR complex from Hsp90, followed by significant degradation of Met and EGFR. By employing patient-derived tumor models we demonstrate therapeutic potential of the BsAb-mediated dual degradation in various cancers.

High-normal free thyroxine levels are associated with low trabecular bone scores in euthyroid postmenopausal women

Trabecular bone scores (TBS) have recently been developed as a diagnostic tool to assess bone texture. We studied thyroid status and TBS in a population-based cohort and demonstrated that high-normal thyroxine levels are associated with low TBS in healthy euthyroid postmenopausal women.

INTRODUCTION

Increased thyroid hormone levels affect bone mineral density (BMD) and, if untreated, increase the risk of fracture. However, the relationship between thyroid function and bone microarchitecture has not yet been established. Trabecular bone scores (TBS) are gray-level textural measurements of dual energy X-ray absorptiometry (DXA) images. The TBS has been proposed as an indirect index of bone microarchitecture. The goal of this study was to characterize the relationship between thyroid function and TBS in euthyroid men and postmenopausal euthyroid women.

METHODS

A total of 1376 euthyroid subjects (648 postmenopausal women and 728 men) were recruited from a community-based cohort in Korea. Free thyroxine (fT4) levels, thyroid stimulating hormone (TSH) levels, BMD, and TBS were measured and compared.

RESULTS

There was no significant relationship between either fT4 or TSH levels and BMD in men and women. Multiple linear regression analysis showed that high-normal fT4 levels were negatively correlated with TBS (β = -0.111; P = 0.002, after adjusting for both age and body mass index [BMI]) in postmenopausal women. In men, however, there was no significant correlation between fT4 levels and TBS. TSH levels were not significantly associated with TBS in either men or women.

CONCLUSION

Higher fT4 levels within the normal reference range are associated with deterioration of trabecular microarchitecture in healthy euthyroid postmenopausal women.

Radiofrequency ablation as an alternative to hepatic resection for single small hepatocellular carcinomas

Background

This study aimed to investigate whether radiofrequency ablation (RFA) is an alternative to surgical resection for hepatocellular carcinoma (HCC) within the context of current guidelines.

Methods

This retrospective study included patients with normal portal pressure and serum bilirubin level who initially underwent liver resection or RFA for a single HCC of maximum size 3 cm. Between-group differences in cumulative rates of survival and recurrence specific for HCC were analysed in the entire cohort and in a propensity score-matched cohort.

Results

A total of 604 patients were enrolled, 273 in the liver resection group and 331 in the RFA group. The 5- and 10-year HCC-specific survival rates for the resection and RFA groups were 87·6 versus 82·1 per cent and 59·0 versus 61·2 per cent respectively (P = 0·214), whereas overall 5- and 10-year recurrence-free survival rates for the corresponding groups were 60·6 versus 39·4 per cent and 37·5 versus 25·1 per cent respectively (P &lt; 0·001). In the propensity score-matched cohort (152 pairs), there were no differences in HCC-specific survival (hazard ratio (HR) 1·03 for RFAversus resection; P = 0·899), whereas recurrence-free survival again differed between the treatment groups (HR 1·75; P &lt; 0·001). RFA was independently associated with poorer outcomes in terms of treatment-site recurrence-free survival (adjusted HR 1·66; P = 0·026), but not non-treatment-site recurrence-free survival (adjusted HR 1·15; P = 0·354).

Conclusion

Although RFA carries a higher risk of treatment-site recurrence than hepatic resection, it provides comparable overall survival in patients with a single small HCC without portal hypertension or a raised bilirubin level.

Stabilization of ferromagnetic ordering in cobaltite double perovskites of La₂CoIrO₆ and La₂CoPtO₆

We investigated the local electronic structure and magnetic properties of the cobaltite double perovskites La2CoIrO6 and La2CoPtO6 using Co L2,3-edge x-ray absorption spectroscopy and x-ray magnetic circular dichroism. Despite similarity in the local electronic structure (Co(2+) high-spin states) as well as in the crystal structure (P2(1)/n), only La2CoIrO6 exhibits substantial orbital and spin magnetic moments of Co(2+), whereas they are much weaker in the case of La2CoPtO6. This composition dependence is consistent with the results of magnetization measurements. The details of the mechanism of ferromagnetic ordering in the Co(2+) sublattice in La2CoIrO6 and the lack thereof in La2CoPtO6 are explained in terms of the orbital hybridization of the Co minority-spin t(2g) state and the Ir/Pt j(eff) = 1/2 state.

Health Implications of Adults' Eating at and Living near Fast Food or Quick Service Restaurants

Background:

This paper examined whether the reported health impacts of frequent eating at a fast food or quick service restaurant on health were related to having such a restaurant near home.

Methods:

Logistic regressions estimated associations between frequent fast food or quick service restaurant use and health status, being overweight or obese, having a cardiovascular disease or diabetes, as binary health outcomes. In all, 2001 participants in the 2008–2009 Seattle Obesity Study survey were included in the analyses.

Results:

Results showed eating ⩾2 times a week at a fast food or quick service restaurant was associated with perceived poor health status, overweight and obese. However, living close to such restaurants was not related to negative health outcomes.

Conclusions:

Frequent eating at a fast food or quick service restaurant was associated with perceived poor health status and higher body mass index, but living close to such facilities was not.

Differences in Buying Behavior of Self-Lovers According to the Form of Self-Love

We assessed whether or not individuals high in narcissism and those with high self-efficacy showed different behaviors in buying situations, by collecting quantitative responses to scenarios using an online questionnaire. The Study 1 participants comprised 133 students at universities offering 4-year college courses and Study 2 participants were 83 workers and 15 university students. Results of Study 1 showed that narcissists depended more on visual information whereas people with high self-efficacy depended more on attribute information. In particular, covert, unlike overt, narcissists depended on visual information in private buying situations. In contrast, people with high self-efficacy were found to depend on attribute information in public buying situations in which they could display their ability to others. In Study 2, behavioral differences were verified between narcissists and people with high self-efficacy depending on display methods. Narcissists preferred brand displays, whereas people with high self-efficacy preferred product displays.

Analysis of aberrantly spliced transcripts of a novel de novo GNAS mutant in a male with albright hereditary osteodystrophy and PHP1A

Pseudohypoparathyroidism (PHP) is a genetic disorder due to target-organ unresponsiveness to parathyroid hormone (PTH). PHP type 1A (PHP1A) is an autosomal dominant disease characterized by Albright hereditary osteodystrophy (AHO) and PTH resistance caused by defects at the GNAS locus. We analyzed the GNAS gene in a male with typical AHO and elevated PTH levels. We identified a novel de novo heterozygous mutation at the splice donor site in intron-7 (IVS7+1G>A, c.585+1G>A) of the GNAS gene. No GNAS mutations were detected in his parents. Our patient was diagnosed with PHP1A due to a heterozygous de novo mutation in the GNAS gene. Reverse transcriptase (RT) PCR analysis and sequencing revealed that this de novo splice mutation generated alternative splicing errors leading to the formation of 2 mutant transcripts: one with exon-7 deleted, the other with whole intron-7 included. To investigate whether these aberrantly spliced transcripts were stable, we assessed the differential expression of GNAS mRNAs in the proband's blood by real-time quantitative RT-PCR. In the proband, the relative expression levels of wild-type, exon-7-deleted, and intron-7-included GNAS mRNAs were 0.21, 6.12E-07, and 1.08E-04, respectively, relative to wild-type GNAS mRNA from a healthy control (set at 1.0). This suggests that this novel de novo splicing mutation generates rapidly decaying mutant transcripts, which might affect stimulatory G-protein activity and give rise to this sporadic case. In conclusion, this is an interesting report of aberrantly spliced mRNAs from a de novo splice mutation of the GNAS gene causing PHP1A in a male.

A novel antibody-drug conjugate targeting SAIL for the treatment of hematologic malignancies

Although several new therapeutic approaches have improved outcomes in the treatment of hematologic malignancies, unmet need persists in acute myeloid leukemia (AML), multiple myeloma (MM) and non-Hodgkin's lymphoma. Here we describe the proteomic identification of a novel cancer target, SAIL (Surface Antigen In Leukemia), whose expression is observed in AML, MM, chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). While SAIL is widely expressed in CLL, AML, MM, DLBCL and FL patient samples, expression in cancer cell lines is mostly limited to cells of AML origin. We evaluated the antitumor activity of anti-SAIL monoclonal antibodies, 7-1C and 67-7A, conjugated to monomethyl auristatin F. Following internalization, anti-SAIL antibody–drug conjugates (ADCs) exhibited subnanomolar IC₅₀ values against AML cell lines in vitro. In pharmacology studies employing AML cell line xenografts, anti-SAIL ADCs resulted in significant tumor growth inhibition. The restricted expression profile of this target in normal tissues, the high prevalence in different types of hematologic cancers and the observed preclinical activity support the clinical development of SAIL-targeted ADCs.

Cell population data in neonates: differences by age group and associations with perinatal factors

INTRODUCTION

Cell population data (CPD) describe physical parameters of white blood cell subpopulations and are reported to be of some value in the diagnosis of sepsis in neonates. Before using the CPD for diagnosing sepsis, the baseline features of the CPD distribution in healthy neonates should be clarified. The aim of this study was to compare the CPD distributions of healthy neonates and other age groups and to identify perinatal factors that are associated with changes in the CPD distribution of healthy neonates.

METHODS

The CPD distribution of 69 samples from term neonates was compared with adolescents and adults. The CPD distribution of 163 samples from healthy neonates was analyzed in association with perinatal factors, including gestational age, chronologic age, birthweight, delivery mode, premature rupture of membranes, diabetes, and pregnancy-induced hypertension.

RESULTS

The CPD distribution for term neonates was significantly different from those in adolescents and adults. The mean lymphocyte volume showed a negative correlation with gestational age at birth (r = -0.305; P < 0.01). The mean neutrophil volume was smaller in the cesarean section group than in the normal delivery group. The small for gestational age (SGA) group had smaller mean neutrophil volume and mean monocyte volume than the appropriate for gestational age group.

CONCLUSION

The CPD distribution of healthy neonates differed from those of adolescents or adults, and the differences were associated with gestational age, delivery mode, and being SGA.

Macrophage activation syndrome in a newborn infant born to a mother with autoimmune disease

Macrophage activation syndrome (MAS) is a complication of rheumatic disorders characterized by cytopenia, multiple organ dysfunction and coagulopathy associated with an inappropriate activation of macrophage. In neonatal lupus erythematosus, MAS is rare but fatal, requiring early diagnosis and treatment for optimal outcome. We report a case of MAS in a neonate born to a mother with autoimmune disease, improved by treatment with steroid, intravenous immunoglobulin and cyclosporine.

PPARγ induces growth inhibition and apoptosis through upregulation of insulin-like growth factor-binding protein-3 in gastric cancer cells

Peroxisome proliferator activator receptor-gamma (PPARγ) is a ligand-activated transcriptional factor involved in the carcinogenesis of various cancers. Insulin-like growth factor-binding protein-3 (IGFBP-3) is a tumor suppressor gene that has anti-apoptotic activity. The purpose of this study was to investigate the anticancer mechanism of PPARγ with respect to IGFBP-3. PPARγ was overexpressed in SNU-668 gastric cancer cells using an adenovirus gene transfer system. The cells in which PPARγ was overexpressed exhibited growth inhibition, induction of apoptosis, and a significant increase in IGFBP-3 expression. We investigated the underlying molecular mechanisms of PPARγ in SNU-668 cells using an IGFBP-3 promoter/luciferase reporter system. Luciferase activity was increased up to 15-fold in PPARγ transfected cells, suggesting that PPARγ may directly interact with IGFBP-3 promoter to induce its expression. Deletion analysis of the IGFBP-3 promoter showed that luciferase activity was markedly reduced in cells without putative p53-binding sites (-Δ1755, -Δ1795). This suggests that the critical PPARγ-response region is located within the p53-binding region of the IGFBP-3 promoter. We further demonstrated an increase in PPARγ-induced luciferase activity even in cells treated with siRNA to silence p53 expression. Taken together, these data suggest that PPARγ exhibits its anticancer effect by increasing IGFBP-3 expression, and that IGFBP-3 is a significant tumor suppressor.

Quantification of the placental epigenetic signature of the SERPINB5 gene in maternal plasma of pregnancies complicated by small for gestational age

INTRODUCTION

To investigate the association between pregnancies with small for gestational age (SGA) neonates and the concentration of cell-free fetal DNA or cell-free total DNA in maternal plasma during the first and second trimesters using tissue-specific epigenetic characteristics of the SERPINB5 gene.

METHODS

A nested case-control study was conducted with maternal plasma collected at 11 to 26 gestational weeks from 51 women with SGA neonates and 102 controls. We performed a real-time quantitative methylation-specific PCR to quantify concentrations of unmethylated-SERPINB5 (U-SERPINB5) as a cell-free fetal DNA marker and methylated-SERPINB5 (M-SERPINB5) as a cell-free total DNA marker.

RESULTS

A positive correlation was observed between U-SERPINB5 and M-SERPINB5 concentrations in both control (r = 0.363, p < 0.001) and SGA groups (r = 0.548, p < 0.001). Moreover, the concentration of U-SERPINB5 or M-SERPINB5 was significantly positive correlated with gestational age at sampling in both controls (U-SERPINB5: r = 0.397, p < 0.001; M-SERPINB5: r = 0.275, p = 0.005) and SGA (U-SERPINB5: r = 0.274, p = 0.052; M-SERPINB5: r = 0.439, p = 0.001). However, the concentration of U-SERPINB5 or M-SERPINB5 was not correlated with birthweight. At 11-14 weeks, U-SERPINB5 and M-SERPINB5 concentrations in SGA did not differ significantly from those of controls. There were also no statistically significant differences in the concentrations of U-SERPINB5 and M-SERPINB5 between SGA and controls at 15-26 weeks of gestation.

DISCUSSION

Our findings suggest that U-SERPINB5 and M-SERPINB5 concentrations in maternal plasma during early pregnancy are not associated with pregnancies who delivered SGA neonates.

Forced arterial suction thrombectomy with the penumbra reperfusion catheter in acute basilar artery occlusion: a retrospective comparison study in 2 Korean university hospitals

BACKGROUND AND PURPOSE

A performance of forced arterial suction thrombectomy was not reported for the treatment of acute basilar artery occlusion. This study compared revascularization performance between intra-arterial fibrinolytic treatment and forced arterial suction thrombectomy with a Penumbra reperfusion catheter in patients with acute basilar artery occlusion.

MATERIALS AND METHODS

Fifty-seven patients with acute basilar artery occlusion were treated with intra-arterial fibrinolysis (n = 25) or forced arterial suction thrombectomy (n = 32). Baseline characteristics, successful revascularization rate, and clinical outcomes were compared between the groups.

RESULTS

Baseline characteristics, the frequency of patients receiving intravenous recombinant tissue plasminogen activator, and mean time interval between symptom onset and femoral puncture did not differ between groups. The forced arterial suction thrombectomy group had a shorter procedure duration (75.5 minutes versus 113.3 minutes, P = .016) and higher successful revascularization rate (88% versus 60%, P = .017) than the fibrinolysis group. Fair outcome, indicated by a modified Rankin Scale 0-3, at 3 months was achieved in 34% of patients undergoing forced arterial suction thrombectomy and 8% of patients undergoing fibrinolysis (P = .019), and the mortality rate was significantly higher in the fibrinolysis group (25% versus 68%, P = .001). Multiple logistic regression analysis identified the forced arterial suction thrombectomy method as an independent predictor of fair outcome with adjustment for age, sex, initial NIHSS score, and the use of intravenous recombinant tissue plasminogen activator (odds ratio, 7.768; 95% CI, 1.246-48.416; P = .028).

CONCLUSIONS

In acute basilar artery occlusion, forced arterial suction thrombectomy demonstrated a higher revascularization rate and improved clinical outcome compared with traditional intra-arterial fibrinolysis. Further clinical trials with the newer Penumbra catheter are warranted.

Antihistamines modulate the integrin signaling pathway in h9c2 rat cardiomyocytes: Possible association with cardiotoxicity

The identification of biomarkers for toxicity prediction is crucial for drug development and safety evaluation. The selective and specific biomarkers for antihistamines-induced cardiotoxicity is not well identified yet. In order to evaluate the mechanism of the life-threatening effects caused by antihistamines, we used DNA microarrays to analyze genomic profiles in H9C2 rat cardiomyocytes that were treated with antihistamines. The gene expression profiles from drug-treated cells revealed changes in the integrin signaling pathway, suggesting that cardiac arrhythmias induced by antihistamine treatment may be mediated by changes in integrin-mediated signaling. It has been reported that integrin plays a role in QT prolongation that may induce cardiac arrhythmia. These results indicate that the integrin-mediated signaling pathway induced by antihistamines is involved in various biological mechanisms that lead to cardiac QT prolongation. Therefore, we suggest that genomic profiling of antihistamine-treated cardiomyocytes has the potential to reveal the mechanism of adverse drug reactions, and this signal pathway is applicable to prediction of in vitro cardiotoxicity induced by antihistamines as a biomarker candidate.

Association between pelvic organ prolapse and bone mineral density in postmenopausal women

Both pelvic organ prolapse (POP) and osteoporosis are age-related diseases in older aged women. Both POP and bone metabolism may be associated with collagen metabolism. Our study determined the relationship between POP and bone mineral density (BMD) of the lumbar spine and femur neck in postmenopausal women. We selected 554 postmenopausal women (aged 50-79 years) and divided them into two groups (moderate to severe POP and absent to mild POP). We compared the BMDs of the lumbar spine and femur neck between the moderate to severe POP and absent to mild POP groups. Lumbar spine BMD was inversely correlated with POP severity (p = 0.001). However, after adjusting for age, time since menopause, height, weight, body mass index (BMI), and vaginal delivery, the BMDs of both the lumbar spine and femur neck were not significantly different between the moderate to severe POP and absent to mild POP groups (p = 0.583 and p = 0.305, respectively). A lower BMD is associated with increased fracture risk and we postulated that women with severe POP would have an increased risk of osteoporotic fracture.

Association between vitamin D deficiency and tuberculosis in a Korean population

BACKGROUND

Several in vitro studies have been conducted regarding the immunomodulatory and mycobactericidal roles of vitamin D in tuberculous infection. However, discrepancies exist among epidemiological studies. We compared vitamin D deficiency between patients with tuberculosis (TB) and healthy control subjects and identified risk factors for vitamin D deficiency.

METHOD

This was an age- and sex-matched case-control analysis of 94 TB cohort and 282 Korean national survey participants.

RESULTS

The median baseline 25-hydroxyvitamin D (25[OH]D) level in the TB group (9.86 ng/ml, IQR 7.19-14.15) was lower than in controls (16.03 ng/ml, IQR 12.38-20.30, P < 0.001). The prevalence of severe vitamin D deficiency was higher in patients with TB (51.1%) than in controls (8.2%, P = 0.001). The median 25(OH)D level increased from 11.40 ng/ml (IQR 7.85-15.73) to 13.18 ng/ml (IQR 10.60-19.71) after treatment completion (P = 0.037). On multivariate analysis, presence of TB and history of TB were independently associated with severe vitamin D deficiency.

CONCLUSION

Patients with TB had a higher prevalence of vitamin D deficiency than control subjects in a Korean population. The median 25(OH)D level increased after TB treatment. Further studies are needed to establish a causal relationship.

Identification of novel mutations in the VPS33B gene involved in arthrogryposis, renal dysfunction, and cholestasis syndrome

Arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome is an autosomal recessive disorder caused by mutations in the VPS33B and VIPAS39. Here, we report novel mutations identified in four patients with ARC syndrome. We analyzed the entire coding regions of the VPS33B and VIPAS39 genes by direct sequencing. To detect novel splice site mutations, mRNA transcripts were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing. All four patients had compound heterozygous variants in the VPS33B gene. One patient had a previously reported splice site variant with unknown significance, c.239+5G>A, and a novel nonsense mutation, c.621G>A. The other three patients had the c.403+2T>A mutation, and each of them carried one of the splice site variants, c.239+5G>A or c.499-11G>A. c.239+5G>A and c.499-11G>A created novel splice sites which resulted in abnormal transcripts. No significant VIPAS39 mutation was detected in all patients. In patients suspected with ARC syndrome, mutation analysis of the VPS33B gene should be employed as a primary diagnostic test before performing invasive testing procedures such as organ biopsies. Performing mRNA analysis can be useful in predicting the pathogenic phenotype when the mutation seems to affect a normal splicing mechanism.