Prenatal diagnosis of cardiac rhabdomyomas: incidence of associated cerebral lesions of tuberous sclerosis complex

Early Diagnosis of Tuberous Sclerosis Complex: Prenatal Diagnosis

BACKGROUND AND PURPOSE

Strong emphasis has been placed recently on early (4 postnatal months) detection of tuberous sclerosis complex and the introduction of antiepileptic treatment before seizure onset. This objective can be achieved prenatally: Cardiac rhabdomyomas and the major diagnostic tuberous sclerosis complex sign are detected during fetal ultrasound, and prenatal MR imaging allows detection of cerebral major manifestations: cortical tubers, subependymal nodules, and subependymal giant cell astrocytomas.

MATERIALS AND METHODS

We retrospectively reviewed 50 fetuses with ultrasound-detected cardiac tumors at 19-36 gestational weeks (median, 31 weeks). MR imaging with the use of 1.5T scanners was performed at 24-37 gestational weeks (median, 34 weeks).

RESULTS

In 11 fetuses (22%), cardiac tumors remained the only criterion. In remaining 39 fetuses (78%), MR imaging revealed a prenatal diagnosis of tuberous sclerosis complex, having shown an additional 1-3 major criteria: subependymal nodules in all cases (39/39 = 100.0%), subependymal giant cell astrocytomas in 6 (6/39 = 15.4%), and cortical tubers in 24 (24/39 = 61.5%). Radial migration lines and cerebellar tuber, not published so far, were shown in 1 case each.

CONCLUSIONS

A schedule of proper care of children with tuberous sclerosis complex can be established during the perinatal period due to education of women to report for mandatory ultrasound examinations during pregnancy, the good quality of ultrasound, and referral to MR imaging if a cardiac tumor is depicted on ultrasound. Gynecologists and pediatric cardiologists performing fetal ultrasound and radiologists performing prenatal MR imaging are a key to early diagnosis of tuberous sclerosis complex in many cases.

MicroRNA-34a activation in tuberous sclerosis complex during early brain development may lead to impaired corticogenesis

AIMS

Tuberous sclerosis complex (TSC) is a genetic disorder associated with dysregulation of the mechanistic target of rapamycin complex 1 (mTORC1) signalling pathway. Neurodevelopmental disorders, frequently present in TSC, are linked to cortical tubers in the brain. We previously reported microRNA-34a (miR-34a) among the most upregulated miRs in tubers. Here, we characterised miR-34a expression in tubers with the focus on the early brain development and assessed the regulation of mTORC1 pathway and corticogenesis by miR-34a.

METHODS

We analysed the expression of miR-34a in resected cortical tubers (n = 37) compared with autopsy-derived control tissue (n = 27). The effect of miR-34a overexpression on corticogenesis was assessed in mice at E18. The regulation of the mTORC1 pathway and the expression of the bioinformatically predicted target genes were assessed in primary astrocyte cultures from three patients with TSC and in SH-SY5Y cells following miR-34a transfection.

RESULTS

The peak of miR-34a overexpression in tubers was observed during infancy, concomitant with the presence of pathological markers, particularly in giant cells and dysmorphic neurons. miR-34a was also strongly expressed in foetal TSC cortex. Overexpression of miR-34a in mouse embryos decreased the percentage of cells migrated to the cortical plate. The transfection of miR-34a mimic in TSC astrocytes negatively regulated mTORC1 and decreased the expression of the target genes RAS related (RRAS) and NOTCH1.

CONCLUSIONS

MicroRNA-34a is most highly overexpressed in tubers during foetal and early postnatal brain development. miR-34a can negatively regulate mTORC1; however, it may also contribute to abnormal corticogenesis in TSC.

Fetal Brain Magnetic Resonance Imaging Findings Predict Neurodevelopment in Children with Tuberous Sclerosis Complex

OBJECTIVE

To correlate fetal brain magnetic resonance imaging (MRI) findings with epilepsy characteristics and neurodevelopment at 2 years of age in children with tuberous sclerosis complex (TSC) to improve prenatal counseling.

STUDY DESIGN

This retrospective cohort study was performed in a collaboration between centers of the EPISTOP consortium. We included children with definite TSC, fetal MRIs, and available follow-up data at 2 years of age. A pediatric neuroradiologist masked to the patient's clinical characteristics evaluated all fetal MRIs. MRIs were categorized for each of the 10 brain lobes as score 0: no (sub)cortical lesions or doubt; score 1: a single small lesion; score 2: more than one small lesion or at least one large lesion (>5 mm). Neurologic manifestations were correlated to lesion sum scores.

RESULTS

Forty-one children were included. Median gestational age at MRI was 33.3 weeks; (sub)cortical lesions were detected in 97.6%. Mean lesion sum score was 4.5. At 2 years, 58.5% of patients had epilepsy and 22% had drug-resistant epilepsy. Cognitive, language, and motor development were delayed in 38%, 81%, and 50% of patients, respectively. Autism spectrum disorder (ASD) was diagnosed in 20.5%. Fetal MRI lesion sum scores were significantly associated with cognitive and motor development, and with ASD diagnosis, but not with epilepsy characteristics.

CONCLUSIONS

Fetal cerebral lesion scores correlate with neurodevelopment and ASD at 2 years in children with TSC.

Benign Structures Mimicking Right Atrial Masses on Prenatal Ultrasound

Advances in imaging have resulted in more frequent reporting of primitive right atrial structures which can sometimes mimic cardiac tumors in prenatal ultrasound. Prominent crista terminalis and Chiari network are examples of these structures. We describe two cases of pregnant women referred to the fetal cardiology clinic for fetal echocardiography for right atrial masses seen on prenatal ultrasound suspicious of tuberous sclerosis. The first case subsequently diagnosed as crista terminalis and the second case as a prominent Chiari network. Postnatal ECHO confirmed the benign nature of these structures. It is important to differentiate tumors from prominent benign structures in the right atrium in fetal ECHO. The location and the similar echogenicity to the adjacent atrial tissue are clues for differentiation of these structures from atrial tumors.

A Multidisciplinary Approach in Prenatal Diagnosis of TSC With Cardiac Rhabdomyoma as the Initial Symptom

The long-term prognosis of a fetus with cardiac rhabdomyoma (CR) depends on the correlation with tuberous sclerosis complex (TSC). In recent years, the numerous variations of uncertain significance (VUS) of TSC genes produced by high-throughput sequencing have made counseling challenging, studies until now have tended to side-step the tricky topics. Here, we integrated detailed parental phenotype, echocardiography, neuro MRI, and genetic information to conduct a comprehensive evaluation of 61 CR fetuses. As a result, multiple CRs and cerebral lesions appeared in 90 and 80%, respectively of fetuses with pathogenic (P)/likely pathogenic (LP) TSC1/TSC2 variations. Overall, 85.7% of the live-born infants with P/LP presented with TSC-associated signs. While, 85.7% of VUS without nervous findings had good prognoses. Genetic evidence and cerebral MRI findings are the most sensitive index to assess long-term prognosis, which complement and confirm each other for a TSC diagnosis. In total, 68.9% of fetuses with CR could benefit from this multidisciplinary approach, which turned out to be potentially clinically actionable with precise clinical/genetic diagnosis or had a foreseeable outcome. Our practice provides a practical and feasible solution for perinatal management and prognostic guidance for fetuses with CR.

Ante-natal counseling in phacomatoses

OBJECTIVES

Phacomatoses are a group of neuro-oculo-cutaneous syndromes/ neurocutaneous disorders, involving structures arising from the embryonic ectoderm. Most of phacomatoses including the most common ones:, neurofibromatosis type I and type II (NF1, NF2) and tuberosclerosis complex (TSC), are autosomal dominant genetic disorders with full penetrance and variable expression. As no effective treatment exists, the only way to prevent the disease, is by prenatal genetic diagnosis (either chorionic villus sampling-CVS or amniocentesis-AC) and termination of pregnancy or performing preimplantation genetic testing (PGT). As the risk for an affected offspring is 50% in every pregnancy of an affected parent, prenatal, and preimplantation testing are of great importance. However, those procedures are associated with technical and ethical concerns. This chapter shortly reviews the common phacomatoses emphasizes their genetics and inheritance. We will review the common methods for prenatal and preimplantation diagnoses and discuss its use in common phacomatoses.

CONCLUSION

Phacomatoses are common autosomal dominant genetic conditions with variable expression. Ante-natal genetic diagnosis is an appropriate approach for family planning in individuals affected by phacomatosis or parents of an affected child.

Progression of Fetal Brain Lesions in Tuberous Sclerosis Complex

Tuberous sclerosis (TSC) is a multisystem autosomal dominant genetic disorder due to loss of function of TSC1/TSC2 resulting in increased mTOR (mammalian target of rapamycin) signaling. In the brain, TSC is characterized by the formation of specific lesions that include subependymal and white matter nodules and cortical tubers. Cells that constitute TSC lesions are mainly Giant cells and dysmorphic neurons and astrocytes, but normal cells also populate the tubers. Although considered as a developmental disorder, the histopathological features of brain lesions have been described in only a limited number of fetal cases, providing little information on how these lesions develop. In this report we characterized the development of TSC lesions in 14 fetal brains ranging from 19 gestational weeks (GW) to term and 2 postnatal cases. The study focused on the telencephalon at the level of the caudothalamic notch. Our data indicate that subcortical lesions, forming within and at the vicinity of germinative zones, are the first alterations (already detected in 19GW brains), characterized by the presence of numerous dysmorphic astrocytes and Giant, balloon-like, cells. Our data show that cortical tuber formation is a long process that initiates with the presence of dysmorphic astrocytes (by 19–21GW), progress with the apparition of Giant cells (by 24GW) and mature with the appearance of dysmorphic neurons by the end of gestation (by 36GW). Furthermore, the typical tuberal aspect of cortical lesions is only reached when bundles of neurofilament positive extensions delineate the bottom of the cortical lesion (by 36GW). In addition, our study reveals the presence of Giant cells and dysmorphic neurons immunopositive for interneuron markers such as calbindin and parvalbumin, suggesting that TSC lesions would be mosaic lesions generated from different classes of progenitors.

Prenatal genetic diagnosis of cardiac rhabdomyoma: A single-center experience

OBJECTIVE

The aim of this study is to review our institution's experience with fetal cardiac rhabdomyoma, and to document the prenatal genetic testing for tuberous sclerosis complex (TSC) and clinical outcome of the affected pregnancies.

STUDY DESIGN

During a four-year period, patients with fetal cardiac rhabdomyoma were detected by echocardiography in the second trimester of pregnancy. Molecular genetic analysis was conducted on fetuses to screen for variants of TSC1/TSC2 genes. We reviewed medical records of these affected pregnancies, including maternal demographics, sonographic findings, genotyping results and pregnancy outcomes.

RESULTS

Eleven cases with fetal cardiac rhabdomyoma were studied during the study period. A pathogenic variant of TSC1/TSC2 genes was detected in all cases, including two with an inherited variant and nine with a de novo variant. Out of these eleven cases diagnosed prenatally, eight pregnancies were terminated and three continued till term.

CONCLUSIONS

Cardiac rhabdomyoma is the prenatal sign of TSC. A molecular investigation of TSC1/TSC2 genes should be recommended for fetuses with a rhabdomyoma and the parents, and the prognostic counselling should include TSC and its consequences.

Fetal cardiac abnormalities: Genetic etiologies to be considered

Congenital heart diseases are a common prenatal finding. The prenatal identification of an associated genetic syndrome or a major extracardiac anomaly helps to understand the etiopathogenic diagnosis. Besides, it also assesses the prognosis, management, and familial recurrence risk while strongly influences parental decision to choose termination of pregnancy or postnatal care. This review article describes the most common genetic diagnoses associated with a prenatal finding of a congenital heart disease and a suggested diagnostic process.

Diagnosis of tuberous sclerosis complex in the fetus

Tuberous sclerosis complex is a dominantly inherited genetic disorder of striking clinical variability. It is caused by mutations in either TSC1 or TSC2 gene, which regulate cell growth and proliferation by inhibition of mTORC1 signaling. TS is characterized by the development of benign tumors in many tissues and organs and its neurological manifestations include epilepsy, autism, cognitive and behavioral dysfunction, and giant cell tumors. With mechanism-based mTOR inhibitors therapy now available for many of its manifestations, early diagnosis of TSC is very important in order to offer appropriate care, long-term surveillance and parental counseling. Fetal ultrasound and MRI imaging techniques have evolved and may capture even earlier the following TSC-associated lesions: cardiac rhabdomyomas, subependymal nodules, cortical tubers and renal cysts. Often these represent an incidental finding during a routine ultrasound. Furthermore, in the past decades prenatal molecular diagnosis of TSC has emerged as an important option for families with a known affected member; however, the existing evidence with regards to the clinical characteristics and long-term outcome of babies diagnosed prenatally with TSC is yet limited and the path that follows early TSC detection merits further research.

Fetal cardiac tumors: clinical features, management and prognosis

Fetal cardiac tumors are rare and usually benign. While echocardiography is a reliable technique for diagnosing fetal cardiac tumors, their definitive diagnosis relies on pathological examination. The strategies used to manage fetal cardiac tumors are challenging. A good clinical result is their complete regression during pregnancy or shortly after birth, as often occurs with cardiac rhabdomyomas. Moreover, the fetal prognosis depends on the nature of the tumors, namely, their location, size, number and associated complications. The active treatment options for symptomatic fetuses depend on the fetal status and may include fetal open surgery, postnatal tumor resection with or without the bridge of intrauterine pericardiocentesis, and thoracoamniotic shunting. The ex utero intrapartum treatment procedure provides an alternative technique for performing fetal open surgery and has shown promising preliminary results in selected cases, but is invasive for both the mother and fetus.

Early Detection of Tuberous Sclerosis Complex: An Opportunity for Improved Neurodevelopmental Outcome

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant condition associated with epilepsy, benign tumors, and variable neurodevelopmental outcomes. The diagnosis is most commonly made after epilepsy onset, although a proportion are diagnosed prenatally. Presymptomatic or early treatment with agents such as vigabatrin offers the hope of improved neurodevelopmental outcome. Therefore early diagnosis, before the onset of seizures, is important. In a cohort of children with TSC, we evaluated the age and mode of initial presentation, assessed the neurocognitive and epilepsy outcome, and analyzed whether those diagnosed before the onset of seizures have a different outcome compared with those diagnosed postseizures.

METHODS

We reviewed patients at the TSC clinic at Sydney Children's Hospital who were born between 2001 and 2015.

RESULTS

A total of 74 patients were identified: 34 (46%) diagnosed preseizure (21 prenatally) and 40 (54%) postseizure. In the preseizure cohort, 77% presented with cardiac rhabdomyoma(s) and 72% developed seizures. The postseizure cohort had more severe epilepsy, requiring more antiepileptic drugs for seizure control (median five, compared with three in the preseizure cohort [P = 0.01]). Developmental disability occurred in 65% of the preseizure cohort compared with 72% of the postseizure cohort. Severe developmental disability most often occurred in children who had their first seizure before age 12 months.

CONCLUSION

Children who are diagnosed with TSC before the onset of seizures have less severe epilepsy and better developmental outcome.

Prenatally Diagnosis and Outcome of Fetuses with Cardiac Rhabdomyoma - Single Centre Experience

BACKGROUND

Cardiac rhabdomyoma (CRs) are the most common primary tumour of the heart in infants and children. Usually are multiple and, basing on the location can cause a haemodynamic disturbance, dysrhythmias or heart failure during the fetal and early postnatal period. CRs have a natural history of spontaneous regression and are closely associated with tuberous sclerosis complex (TSC). It has an association with tuberous sclerosis (TS), and in those, the tumour may regress and disappear completely, or remain consistent in size.

AIM

We aimed to evaluate the prenatal diagnosis, clinical presentation and outcome of CRs and their association with TSC in a single centre. The median follow-up period was three years (range: 6 months - 5 years).

MATERIAL AND METHODS

We reviewed medical records of all fetuses diagnosed prenatally with cardiac rhabdomyoma covering the period January 2010 to December 2016 which had undergone detailed ultrasound evaluation at a single centre with limited technical resources.

RESULTS

Twelve fetuses were included in the study; mostly had multiple tumours and a total of 53 tumours were identified in all patients - the maximum was one fetus with16 tumours. All patients were diagnosed prenatally by fetal echocardiography. In two patient's haemodynamic disturbances during the fetal period was noted and pregnancies have been terminated. After long consultation termination of pregnancy was chosen by the parents in totally 8 cases. In four continuing pregnancies during the first year of live tumours regressed. TSC was diagnosed in all patients during the follow-up.

CONCLUSIONS

Cardiac rhabdomyoma are benign from the cardiovascular standpoint in most affected fetuses. An early prenatal diagnosis may help for an adequate planning of perinatal monitoring and treatment with the involvement of a multidisciplinary team. Large tumour size, the number of tumours and localisation may cause hydrops, and they are significantly associated with poor neonatal outcome.

Everolimus treatment of a newborn with rhabdomyoma causing severe arrhythmia

Rhabdomyoma is the most common cardiac tumour in children often associated with tuberous sclerosis. Arrhythmia caused by cardiac rhabdomyomas may be the initial sign of tuberous sclerosis. Rhabdomyomas unresponsive to other treatments could be successfully managed with everolimus, which has demonstrated benefit in tuberous sclerosis. We report a case of rhabdomyoma causing severe arrhythmia in a newborn managed successfully with everolimus.

Rhabdomyomas and tuberous sclerosis complex: our experience in 33 cases

Background

Rhabdomyomas are the most common type of cardiac tumors in children. Anatomically, they can be considered as hamartomas. They are usually randomly diagnosed antenatally or postnatally sometimes presenting in the neonatal period with haemodynamic compromise or severe arrhythmias although most neonatal cases remain asymptomatic. Typically rhabdomyomas are multiple lesions and usually regress spontaneously but are often associated with tuberous sclerosis complex (TSC), an autosomal dominant multisystem disorder caused by mutations in either of the two genes, TSC1 or TSC2. Diagnosis of tuberous sclerosis is usually made on clinical grounds and eventually confirmed by a genetic test by searching for TSC genes mutations.

Methods

We report our experience on 33 cases affected with rhabdomyomas and diagnosed from January 1989 to December 2012, focusing on the cardiac outcome and on association with the signs of tuberous sclerosis complex. We performed echocardiography using initially a Philips Sonos 2500 with a 7,5/5 probe and in the last 4 years a Philips IE33 with a S12-4 probe. We investigated the family history, brain, skin, kidney and retinal lesions, development of seizures, and neuropsychiatric disorders.

Results

At diagnosis we detected 205 masses, mostly localized in interventricular septum, right ventricle and left ventricle. Only in 4 babies (12%) the presence of a mass caused a significant obstruction. A baby, with an enormous septal rhabdomyoma associated to multiple rhabdomyomas in both right and left ventricular walls died just after birth due to severe heart failure. During follow-up we observed a reduction of rhabdomyomas in terms of both number and size in all 32 surviving patients except in one child. Eight patients (24,2%) had an arrhythmia and in 2 of these cases rhabdomyomas led to Wolf-Parkinson-White Syndrome. For all patients the arrhythmia spontaneously totally disappeared or was reduced gradually. With regarding to association with tuberous sclerosis, we diagnosed tuberous sclerosis clinically in 31 babies (93,9%).

Conclusion

Rhabdobyomas are tumors with favorable prognosis because they frequently do not cause symptoms and they often regress in numbers and size. Nevertheless, due to frequent association with tuberous sclerosis complex and the resulting neurological impairment, the prognosis can result unfavorable.

Recommendations for the radiological diagnosis and follow-up of neuropathological abnormalities associated with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a genetic condition with multisystem involvement, characterized by the development of tumors and other abnormalities in organs such as the brain, retina, skin, heart, kidneys, and lungs. Most patients have neuropathological abnormalities such as cortical tubers, white matter radial migration lines, subependymal nodules, and subependymal giant cell astrocytomas (SEGAs). These lesions are associated with different neurological manifestations that are frequently associated with TSC. These manifestations consist of epilepsy, intellectual disability, and neurobehavioral and psychiatric problems, including autism spectrum disorder. Hydrocephalus may also develop in patients with SEGAs due to ventricular obstruction, when this usually slow-growing tumor reaches sufficient size. Surgery has been the classical approach to treat SEGAs, although this treatment is associated with substantial morbidity and does not completely prevent tumor recurrence. Recently, the mammalian target of rapamycin (mTOR) inhibitor, everolimus, has been approved by the Food and Drug Administration and the European Medicines Agency for the treatment of patients with SEGAs associated with TSC. However, the treatment of SEGAs with these agents requires the development of guidelines that establish a differential diagnosis between SENs and SEGAs, in which neuroradiological examinations play an essential role. With the aim of improving the neuroradiological diagnosis and follow-up of the neuropathological abnormalities associated with TSC, a group of experts in this field has reviewed different aspects related to these issues and put together, a series of statements and recommendations intended to provide guidance to specialists involved in the management of TSC.

MRI and ultrasound fusion imaging for prenatal diagnosis

OBJECTIVE

A combination of magnetic resonance imaging (MRI) images with real time high-resolution ultrasound known as fusion imaging may improve prenatal examination. This study was undertaken to evaluate the feasibility of using fusion of MRI and ultrasound (US) in prenatal imaging.

STUDY DESIGN

This study was conducted in a tertiary referral center. All patients referred for prenatal MRI were offered to undergo fusion of MRI and US examination. All cases underwent 1.5 Tesla MRI protocol including at least 3 T2-weighted planes. The Digital Imaging and Communications in Medicine volume dataset was then loaded into the US system for manual registration of the live US image and fusion imaging examination.

RESULTS

Over the study period, 24 patients underwent fusion imaging at a median gestational age of 31 (range, 24-35) weeks. Data registration, matching and then volume navigation was feasible in all cases. Fusion imaging allowed superimposing MRI and US images therefore providing with real time imaging capabilities and high tissue contrast. It also allowed adding a real time Doppler signal on MRI images. Significant fetal movement required repeat-registration in 15 (60%) cases. The average duration of the overall additional scan with fusion imaging was 10 ± 5 minutes.

CONCLUSION

The combination of fetal real time MRI and US image fusion and navigation is feasible. Multimodality fusion imaging may enable easier and more extensive prenatal diagnosis.

Molecular genetic, cardiac and neurodevelopmental findings in cases of prenatally diagnosed rhabdomyoma associated with tuberous sclerosis complex

OBJECTIVE

Rhabdomyoma is the most common type of cardiac tumor in fetuses and is often associated with tuberous sclerosis complex (TSC) with neurologic sequelae. The purpose of this study was to investigate the cardiac and neurodevelopmental outcomes of fetal rhabdomyoma.

METHODS

We reviewed the clinical characteristics of 23 cases of cardiac rhabdomyoma diagnosed prenatally by fetal echocardiography at the Asan Medical Center between January 1998 and December 2009. We also reviewed postnatal results of brain magnetic resonance imaging, echocardiography, renal ultrasound examination and molecular genetic analysis to confirm the presence of cardiac rhabdomyoma with or without TSC.

RESULTS

Among 23 cases, outcome data were available for 17 (73.9%) and six cases (26.1%) were lost to follow-up. The survival rate was 100.0% (17/17). Among the 17 cases with outcome data, spontaneous tumor regression occurred in eight (47.1%), and no change in tumor size and number was observed in the remaining nine cases (52.9%). There was no evidence of long-term cardiac dysfunction caused by persisting rhabdomyomas, regardless of tumor size. TSC was found in nine patients (52.9%), of whom five (55.6%) showed neurodevelopmental morbidity. We identified mutations in one of the TSC1 or TSC2 genes in four of nine TSC infants whose parents allowed us to perform molecular genetic analysis. Three of these (75.0%) were found to have neurologic impairment. Seven (77.8%) of nine TSC cases were non-familial.

CONCLUSIONS

The overall outcome of isolated cardiac rhabdomyoma appears to be favorable. We suggest that systematic postnatal evaluation of TSC be performed even in cases of cardiac rhabdomyoma without a family history of TSC. Molecular characterization of TSC1 and TSC2 might be helpful in predicting short- and long-term neurodevelopmental outcomes.

Evaluation of the prenatally diagnosed mass

With the advent of advanced imaging technologies, the field of prenatal diagnosis and counseling has grown rapidly. The use of fetal ultrasound and ultrafast magnetic resonance imaging has allowed for prenatal identification of structural anomalies as well as neoplasm. The differential diagnosis of a fetal mass is dependent upon its location and the tissue characteristics of the mass on imaging. The use of amniocentesis for chromosomal analysis and genetic testing for known tumor-related genetic abnormalities may aid in further refining the diagnosis. Herein we describe a general diagnostic algorithm for fetal masses based upon their location within the body and how the appropriate diagnostic modalities may be applied in the clinical setting.