Pregnancy outcomes in women with neurofibromatosis 1: a Danish population-based cohort study.

BACKGROUND: The probability of a pregnancy, live birth, stillbirth and abortion has never been assessed in women with neurofibromatosis 1 (NF1) in a large population-based study. METHODS: We included 1006 women (15-49 years) registered with NF1 in the Danish National Patient Registry or followed in two national Centers for Rare Diseases and 10 020 women from the Danish population. Information on pregnancy outcomes was ascertained from health registries. Cumulative incidence, mean cumulative count, hazard ratios (HRs) and proportion ratios (PRs) with 95% CIs were calculated. RESULTS: The cumulative incidence of a first pregnancy at age 50 years was slightly lower in women with NF1 (74%; 95% CI 70 to 77) than in population comparisons (78%; 95% CI 77 to 79). When all pregnancies were included, two pregnancies were expected per woman at age of 50 years, irrespective of a NF1 diagnosis. The hazard of a pregnancy did not differ between women with NF1 (HR 1.03; 95% CI 0.95 to 1.11) and the comparisons after adjustment for somatic and psychiatric disease. The proportion of pregnancies that resulted in a live birth was 63% (783/1252) among women NF1 and 68% (8432/12 465) among the comparisons, yielding a PR of 0.95 (95% CI 0.90 to 1.00). The proportions of stillbirths (PR 2.83; 95% CI 1.63 to 4.93) and spontaneous abortions (PR 1.40; 95% CI 1.09 to 1.79) were increased in women with NF1. CONCLUSIONS: A similar hazard for pregnancy was observed for women with NF1 and population comparisons after adjustment for potential medical consequences of NF1. However, women with NF1 experienced more spontaneous abortions and stillbirths.

Isolated CHDs and neurodevelopmental follow-up using the Bayley Scales of Infant and Toddler Development and the Ages and Stages Questionnaire at 18 and 36 months.

OBJECTIVES: To compare early neurocognitive development in children born with and without isolated CHD using the Bayley Scales of Infant and Toddler Development (3rd edition) and the Ages and Stages Questionnaire (3rd edition). METHODS: Recruitment took place before birth. Women expecting fetuses with and without CHD causing disturbances in the flow of oxygenated blood to the fetal brain were included in a prospective cohort study comprising fetal MRI (previously published) and neurodevelopmental follow-up. We now present the 18- and 36-month neurodevelopmental follow-up using the Bayley Scales according to age and the 6-month-above-age Ages and Stages Questionnaire in 15 children with and 27 children without CHD. RESULTS: Children with CHD had, compared with the children without CHD, an increased risk of scoring ≤ 100 in the Bayley Scales cognition category at 18 and 36 -months; relative risk 1.7 (95% confidence interval (CI): 1.0-2.8) and 3.1 (CI: 1.2-7.5), respectively. They also achieved lower scores in the 6-month-above-age Ages and Stages Questionnaires (24 and 42 months) communication; mean z-score difference -0.72 (CI: -1.4; -0.1) and -1.06 (CI: -1.8; -0.3) and gross motor; mean z-score difference: -0.87 (CI: -1.7; -0.1) and -1.22 (CI: -2.4; -0.02) categories. CONCLUSIONS: The children with CHD achieved lower scores in the Bayley Scales cognition category and the Ages and Stages Questionnaire communication and gross motor categories possibly indicative of early neurodevelopmental deficiencies. We recommend early screening and monitoring for neurodevelopmental delays in children with CHD in order to improve further neurodevelopment and educational achievements.

Congenital Heart Defects and the Risk of Spontaneous Preterm Birth.

OBJECTIVES: To estimate the association between major types of congenital heart defects (CHD) and spontaneous preterm birth, and to assess the potential underlying mechanisms. STUDY DESIGN: This nationwide, registry-based study included a cohort of all singleton pregnancies in Denmark from 1997 to 2013. The association between CHD and spontaneous preterm birth was estimated by multivariable Cox regression, adjusted for potential confounders. The following potential mechanisms were examined: maternal genetics (sibling analyses), polyhydramnios, preterm prelabor rupture of membranes, preeclampsia, and indicators of fetal and placental growth. RESULTS: The study included 1 040 474 births. Compared with the general population, CHD was associated with an increased risk of spontaneous preterm birth, adjusted hazard ratio 2.1 (95% CI, 1.9-2.4). Several subtypes were associated with increased risks, including pulmonary stenosis combined with a septal defect, 5.2 (95% CI, 3.7-7.5); pulmonary stenosis or atresia, 3.1 (95% CI, 2.4-4.1); tetralogy of Fallot 2.5 (95% CI, 1.6-3.8); coarctation or interrupted aortic arch 2.2 (95% CI, 1.5-3.2); and hypoplastic left heart syndrome, 2.0 (95% CI, 1.0-4.1). Overall, preterm prelabor rupture of membranes mediated more than one-half of the association. Maternal genetics, polyhydramnios, or indicators of fetal or placental growth did not explain the reported associations. CONCLUSIONS: CHD, especially right ventricular outflow tract obstructions, were associated with an increased risk of spontaneous preterm birth. The risk was carried by the CHD and not by maternal genetics. Moreover, preterm prelabor rupture of membranes was identified as a potential underlying mechanism.

Psychiatric disorders in individuals with neurofibromatosis 1 in Denmark: A nationwide register-based cohort study.

The aim of this study was to assess the risks of psychiatric disorders in a large cohort of 905 individuals with NF1 and 7614 population comparisons matched on sex and year of birth. The cohort was linked to the Danish Psychiatric Central Research Register to ascertain information on hospital contacts for psychiatric disorders based on the International Classification of Diseases version 8 and 10. The hazard ratio (HR) for a first psychiatric hospital contact was higher in girls (4.19, 95% confidence interval [CI] 1.81-9.69) and boys with NF1 (5.02, 95% CI 3.27-7.69) <7 years of age than in the population comparisons. Both sexes had increased HRs for developmental disorders, including attention deficit/hyperactivity disorders, autism spectrum disorders, and intellectual disabilities in childhood. Females with NF1 had also increased HRs for unipolar depression, other emotional and behavioral disorders, and severe stress reaction and adjustment disorders in early adulthood. The HRs for psychoses, schizophrenia, bipolar disorders, and substance abuse were similar in individuals with NF1 and the population comparisons. Finally, the cumulative incidence of a first hospital contact due to any psychiatric disorder by age 30 years was 35% (95% CI 29-41) in females and 28% (95% CI 19-37) in males with NF1. Thus, screening for psychiatric disorders may be important for early diagnosis and facilitation of appropriate and effective treatment in individuals with NF1.

Multisystem burden of neurofibromatosis 1 in Denmark: registry- and population-based rates of hospitalizations over the life span.

PURPOSE: The aim was to assess lifetime risk for hospitalization in individuals with neurofibromatosis 1 (NF1). METHODS: The 2467 individuals discharged with a diagnosis indicating NF1 or followed in a clinical center for NF1 were matched to 20,132 general population comparisons. Based on diagnoses in 12 main diagnostic groups and 146 subcategories, we calculated rate ratios (RRs), absolute excess risks (AERs), and hazard ratios for hospitalizations. RESULTS: The RR for any first hospitalization among individuals with NF1 was 2.3 (95% confidence interval 2.2-2.5). A high AER was seen for all 12 main diagnostic groups, dominated by disorders of the nervous system (14.5% of all AERs), benign (13.6%) and malignant neoplasms (13.4%), and disorders of the digestive (10.5%) and respiratory systems (10.3%). Neoplasms, nerve and peripheral ganglia disease, pneumonia, epilepsy, bone and joint disorders, and intestinal infections were major contributors to the excess disease burden caused by NF1. Individuals with NF1 had more hospitalizations and spent more days in hospital than the comparisons. The increased risk for any hospitalization was observed for both children and adults, with or without an associated cancer. CONCLUSION: NF1 causes an overall greater likelihood of hospitalization, with frequent and longer hospitalizations involving all organ systems throughout life.

Clinical history and management recommendations of the smooth muscle dysfunction syndrome due to ACTA2 arginine 179 alterations.

PURPOSE: Smooth muscle dysfunction syndrome (SMDS) due to heterozygous ACTA2 arginine 179 alterations is characterized by patent ductus arteriosus, vasculopathy (aneurysm and occlusive lesions), pulmonary arterial hypertension, and other complications in smooth muscle-dependent organs. We sought to define the clinical history of SMDS to develop recommendations for evaluation and management. METHODS: Medical records of 33 patients with SMDS (median age 12 years) were abstracted and analyzed. RESULTS: All patients had congenital mydriasis and related pupillary abnormalities at birth and presented in infancy with a patent ductus arteriosus or aortopulmonary window. Patients had cerebrovascular disease characterized by small vessel disease (hyperintense periventricular white matter lesions; 95%), intracranial artery stenosis (77%), ischemic strokes (27%), and seizures (18%). Twelve (36%) patients had thoracic aortic aneurysm repair or dissection at median age of 14 years and aortic disease was fully penetrant by the age of 25 years. Three (9%) patients had axillary artery aneurysms complicated by thromboembolic episodes. Nine patients died between the ages of 0.5 and 32 years due to aortic, pulmonary, or stroke complications, or unknown causes. CONCLUSION: Based on these data, recommendations are provided for the surveillance and management of SMDS to help prevent early-onset life-threatening complications.

Gastrointestinal Symptoms in Children and Adolescents With Neurofibromatosis Type 1.

OBJECTIVES: Neurofibromatosis type 1 (NF1) is a complex genetic disorder characterized by symptoms of the skin and nervous system. A previous study indicated that constipation is common in children with NF1. The aim of the present study was to investigate the phenotype and prevalence of gastrointestinal (GI) symptoms in a population of 4 to 17-year-olds with NF1 compared with their unaffected siblings. METHODS: GI symptoms were assessed with a web-based, parent or self-administered, validated, Rome III diagnostic questionnaire. Participants were recruited from 1 of 2 Danish National Centers of Expertise for NF1. Logistic regression was used to estimate the prevalence of functional dyspepsia, irritable bowel syndrome (IBS), and constipation in each group and the groups were compared using odds ratio (OR). RESULTS: We compared 102 NF1 patients (median age 10.3 years) and 46 of their unaffected siblings (median age 10 years). The overall likelihood of having GI symptoms usually attributed to either functional dyspepsia, IBS, or constipation was 30.4% in patients versus 10.9% in siblings, OR 3.58 (95% confidence interval 1.30 to 9.79). The prevalence of constipation was 22.5% in patients and 4.3% in siblings, OR 6.41 (95% confidence interval 1.45 to 28.24). The use of laxatives was 16% (n = 16) in patients and 2% (n = 1) in siblings. CONCLUSIONS: Overall, GI symptoms attributed to functional dyspepsia, IBS or constipation are more common in 4 to 17-year-olds with NF1 when compared with their unaffected siblings. The high prevalence indicates that GI dysfunction in NF1 is not functional but may be part of the underlying NF1 disorder.

Congenital Heart Defects and Indices of Placental and Fetal Growth in a Nationwide Study of 924 422 Liveborn Infants.

BACKGROUND: Congenital heart defects (CHDs) have been associated with placental anomalies. The nature and the consequences of this association remain poorly understood. We aimed to estimate the associations between all major subtypes of CHD and placental weight at birth, and the association between placental weight and measures of both overall and cerebral growth in fetuses with CHD, as well. METHODS: We included all 924 422 liveborn Danish singletons, 1997 to 2011. CHD was present in 7569. We compared mean differences in placental weight z score between newborns with CHD and newborns without CHD by multivariable linear regression adjusted for potential confounders. RESULTS: CHD was associated with a mean z score difference of -0.04 (95% confidence interval, -0.07 to -0.02). Some subtypes were associated with smaller placental size at birth: tetralogy of Fallot, -0.45 (95% confidence interval, -0.58 to -0.31); double-outlet right ventricle, -0.48 (95% confidence interval, -0.87 to -0.10); major ventricular septal defects, -0.41 (95% confidence interval, -0.52 to -0.29). Placental weight z score was associated with birth weight and head circumference z scores in all subtypes. In the 3 mentioned subtypes, the mean deviations from the population mean head circumference and birth weight z scores were reduced by up to 66% with adjustment for placental weight z score. CONCLUSIONS: Three subtypes of CHD were associated with lower placental weight, and placental weight was associated with measures of both overall growth and cerebral growth in fetuses with all subtypes of CHD. In certain subtypes, the described deviations in fetal growth were reduced by up to two-thirds after adjustment for placental weight z score.

Congenital Heart Defects and Indices of Fetal Cerebral Growth in a Nationwide Cohort of 924 422 Liveborn Infants.

BACKGROUND: Neurodevelopmental disorders are the most common and distressful comorbidities associated with congenital heart defects (CHD). Head circumference at birth (HC), a proxy for prenatal cerebral growth, is an established risk factor for neurodevelopmental disorders. METHODS AND RESULTS: In a nationwide cohort, we included all 924 422 liveborn Danish singletons, 1997 to 2011. CHD was present in 5519. The association between CHD and growth indices was analyzed by multivariable linear regression, adjusted for potential confounders. We report mean differences in gestational age-specific z scores in comparison with the general population. CHD was associated with lower HC z scores, -0.10 (95% confidence interval [CI], -0.13 to -0.08). Several CHD subtypes were associated with smaller HC, eg, hypoplastic left heart syndrome, -0.39 (95% CI, -0.58 to -0.21); common arterial trunk, -0.41 (95% CI, -0.74 to -0.09); and major ventricular septal defects, -0.25 (95% CI, -0.35 to -0.15). Other single-ventricle defects, transposition of the great arteries, tetralogy of Fallot, and anomalous pulmonary venous return, were also associated with smaller HC. Transposition of the great arteries was associated with smaller HC relative to birth weight, -0.26 (95% CI, -0.39 to -0.13). Major ventricular septal defects were associated with larger HC relative to birth weight. The results were consistent under various conditions, eg, when siblings of infants with CHD (n=5311) or infants with other major malformations (n=24 974) were used as the reference. CONCLUSIONS: Several subtypes of CHD were associated with smaller HC. The associations with major ventricular septal defects, common arterial trunk, and anomalous pulmonary venous return have not previously been described. Only infants with transposition of the great arteries had smaller HC relative to birth weight.

Development of hypomelanotic macules is associated with constitutive activated mTORC1 in tuberous sclerosis complex.

TSC1 and TSC2 are genes mutated in the syndrome TSC (tuberous sclerosis complex). We describe a 3-generation family with 17 affected members, all presenting classic TSC features except renal manifestations. The disease segregates with a silent substitution in TSC2, c.4149C>T, p.(Ser1383Ser), which leads to the formation of an active donor splice site, resulting in three shorter alternatively spliced transcripts with premature stop codons. However a small amount of normal spliced transcript is apparently produced from the mutated allele, which might explain the milder phenotype. The gene products of TSC1/2 form a complex which at energy limiting states, down-regulates the activity of the regulator of protein synthesis, the mammalian target of rapamycin complex1 (mTORC1). As expected, in contrast to cultured control fibroblasts, starvation of cultured patient fibroblasts obtained from a hypomelanotic macule did not lead to repression of mTORC1, whereas partial repression was observed in patient fibroblasts obtained from non-lesional skin. The findings indicate that the development of hypomelanotic macules is associated with constitutive activated mTORC1, whereas mild deregulation of mTORC1 allows the maintenance of normal skin. Furthermore, the finding establishes the pathogenic effect of the "silent" c.4149C>T substitution and emphasizes the need for awareness when interpreting silent substitutions in general.

Nance-Horan syndrome-The oral perspective on a rare disease.

The present study describes seven patients with Nance-Horan syndrome, all referred to a specialized oral care unit in the Central Denmark Region. A literature search on "Nance Horan Syndrome" resulted in 53 publications among which 29 reported on dental findings. Findings reported in these papers have been systematized to obtain an overview of the reported findings and the terminology on dental morphology. All seven patients included in the present study showed deviations of crown morphology on incisors and/or molars. The only consistent and very clear dental aberration was alterations in the tooth morphology that is screwdriver-shaped incisors and bud molars being most pronounced in the permanent dentition, but were also present in the primary dentition. In addition, three patients had supernumerary teeth, and three had dental agenesis. In conclusion, a dental examination as a part of the diagnostic process may reveal distinct characteristics of the dental morphology, which could be of diagnostic value and facilitate an early diagnosis. In the description of molar morphology in NHS patients, it is recommended to use the term "bud molar." The combination of congenital cataract, screwdriwer-shaped incisors and bud-shaped molars is a strong clinical indication of Nance-Horan syndrome. © 2016 Wiley Periodicals, Inc.

Difficulties in diagnosing Marfan syndrome using current FBN1 databases.

PURPOSE: The diagnostic criteria of Marfan syndrome (MFS) highlight the importance of a FBN1 mutation test in diagnosing MFS. As genetic sequencing becomes better, cheaper, and more accessible, the expected increase in the number of genetic tests will become evident, resulting in numerous genetic variants that need to be evaluated for disease-causing effects based on database information. The aim of this study was to evaluate genetic variants in four databases and review the relevant literature. METHODS: We assessed background data on 23 common variants registered in ESP6500 and classified as causing MFS in the Human Gene Mutation Database (HGMD). We evaluated data in four variant databases (HGMD, UMD-FBN1, ClinVar, and UniProt) according to the diagnostic criteria for MFS and compared the results with the classification of each variant in the four databases. RESULTS: None of the 23 variants was clearly associated with MFS, even though all classifications in the databases stated otherwise. CONCLUSION: A genetic diagnosis of MFS cannot reliably be based on current variant databases because they contain incorrectly interpreted conclusions on variants. Variants must be evaluated by time-consuming review of the background material in the databases and by combining these data with expert knowledge on MFS. This is a major problem because we expect even more genetic test results in the near future as a result of the reduced cost and process time for next-generation sequencing.Genet Med 18 1, 98-102.

Congenital Heart Defects and Measures of Fetal Growth in Newborns with Down Syndrome or 22q11.2 Deletion Syndrome.

OBJECTIVES: To estimate the association between congenital heart defects (CHD) and indices of fetal growth in Down and 22q11.2 deletion syndromes. STUDY DESIGN: We established 2 Danish nationwide cohorts of newborn singletons with either Down syndrome (n = 670) or 22q11.2 deletion syndrome (n = 155), born 1997-2011. In both cohorts, we analyzed the association between CHD, CHD severity, and indices of fetal growth by multivariable linear regression adjusted for potential confounders. We report mean differences in gestational age specific z-scores compared with newborns without CHD. RESULTS: Down syndrome and 22q11.2 deletion syndrome were both associated with lower mean birth weight and head circumference z-scores. We found no association between CHD or CHD severity and indices of fetal growth. In Down syndrome, the association between any CHD and the mean difference in head circumference z-score was 0.03 (95% CI -0.12, 0.18), and the estimate regarding birth weight z-score was 0.09 (95% CI -0.08, 0.25). The corresponding estimates in 22q11.2 deletion syndrome were 0.00 (95% CI -0.33, 0.32) and -0.09 (95% CI -0.45, 0.26). CONCLUSIONS: We found no association between CHD and fetal growth measures in newborns with Down syndrome or 22q11.2 deletion syndrome. Thus, in certain subtypes of CHD, the contribution of genetic factors to prenatal growth impairment may be more important than circulatory disturbances.

Cantú syndrome is caused by mutations in ABCC9.

Cantú syndrome is a rare disorder characterized by congenital hypertrichosis, neonatal macrosomia, a distinct osteochondrodysplasia, and cardiomegaly. Using an exome-sequencing approach applied to one proband-parent trio and three unrelated single cases, we identified heterozygous mutations in ABCC9 in all probands. With the inclusion of the remaining cohort of ten individuals with Cantú syndrome, a total of eleven mutations in ABCC9 were found. The de novo occurrence in all six simplex cases in our cohort substantiates the presence of a dominant disease mechanism. All mutations were missense, and several mutations affect Arg1154. This mutation hot spot lies within the second type 1 transmembrane region of this ATP-binding cassette transporter protein, which may suggest an activating mutation. ABCC9 encodes the sulfonylurea receptor (SUR) that forms ATP-sensitive potassium channels (K(ATP) channels) originally shown in cardiac, skeletal, and smooth muscle. Previously, loss-of-function mutations in this gene have been associated with idiopathic dilated cardiomyopathy type 10 (CMD10). These findings identify the genetic basis of Cantú syndrome and suggest that this is a new member of the potassium channelopathies.

Phenotype of a child with Angelman syndrome born to a woman with Prader-Willi syndrome.

This report describes the phenotype, from early childhood to adolescence, of a girl with Angelman syndrome (AS) born following a maternal transmission of a germline paternal 15q11.2-q13 deletion. During early childhood, she showed a typical AS phenotype, such as jerky movements, poor sleep, high voltage electroencephalography pattern, epilepsy, and a severe developmental disability. As she grew older, indications of phenotypical traits similar to Prader-Willi syndrome (PWS) appeared, in particular hyperphagic behavior and a body fat distribution similar to that reported in PWS. She generally showed cheerful AS behavior and had the characteristic outbursts of laughter, but her attitude to other people did not reflect the usual shared enjoyment of interaction seen in children with AS. In unfamiliar surroundings, she withdrew socially, similar to children with PWS, and her insistence on the same, rigid routines was similar to behavior patterns in PWS. The dysmorphic facial features that characterize AS were blurred in adolescence. The specified features that this AS patient had in common with PWS were hardly incidental and, if verified by upcoming case reports of children born to women with a paternal 15q11.2-q13 deletion, they may show new aspects of genetic imprinting.

Diagnostic practice of psychogenic nonepileptic seizures (PNES) in the pediatric setting.

OBJECTIVE: No formal guidelines for diagnosing psychogenic nonepileptic seizures (PNES) in children exist, and little is known about the clinical practice of diagnosing PNES in the pediatric setting. We therefore performed a national survey as a first step to document pediatricians' current diagnostic practice for PNES. METHODS: A questionnaire was distributed to all pediatricians (n=64) working in the field of neuropediatrics and/or social pediatrics in the Danish hospital setting to uncover their use of terminology and of the International Classification of Diseases, 10th Revision (ICD-10) codes as well as their clinical diagnostic approach to pediatric PNES. The questionnaire included questions on 18 history and 24 paroxysmal event characteristics. RESULTS: The response rate was 95% (61/64). There was no consensus on which terminology and diagnostic codes to use. Five history characteristics (psychosocial stressors/trauma, sexual abuse, paroxysmal events typically occur in stressful situations, no effect of antiepileptic drugs, and physical abuse) and six paroxysmal event characteristics (resisted eyelid opening, avoidance/guarding behavior, paroxysmal events occur in the presence of others, closed eyes, rarely injury related to paroxysmal event, and absence of postictal change) were agreed to be very predictive of PNES by at least 50% of the pediatricians. Supplementary diagnostic tests such as blood chemistry measurements (e.g., blood glucose or acute phase reactants; i.e., white blood cell count and C-reactive protein) and electrocardiography were inconsistently used. Only 49% of the respondents reported to use video-electroencephalography (VEEG) frequently as part of their diagnostic procedure. SIGNIFICANCE: To our knowledge, this is the first national survey that offers a systematic insight into the diagnostic practices for children with PNES in the hospital setting. The results demonstrate a need for clinical guidelines to improve and systematize the diagnostic approach for PNES in children.

Impact of child and family characteristics on cerebral palsy treatment.

AIM: The aim of the study was to describe the relationship between the child's and family's characteristics and the most common treatment modalities in a national population-based sample of 8- to 15-year-old children with cerebral palsy. METHOD: A cross-sectional study, based on the Danish Cerebral Palsy Registry. The parents of 462 children answered a questionnaire about their child's treatment and the family's characteristics (living with a single parent, having siblings, living in a city, parental education level). Descriptive and logistic regression analyses were performed for every treatment modality, stratified by Gross Motor Function Classification System (GMFCS) level. RESULTS: An IQ below 85 was associated with weekly therapy in GMFCS level I (adjusted odds ratio [ORadj ] 2.5 [CI 1.1-5.7]) and the use of oral spasmolytics in GMFCS levels III to V (ORadj 3.1 [CI 1.3-7.4]). Older children in GMFCS levels III to V used daily orthoses less frequently (ORadj 0.7 [CI 0.6-0.9] per year). Of all of the family characteristics studied, only the parents' education level had significant associations with more than one treatment modality. INTERPRETATION: A child's cognitive function showed an impact on treatment of the motor impairment in children 8 to 15 years of age with cerebral palsy. Parental education level may influence the choice of treatment.

Teenagers and young adults with neurofibromatosis type 1 are more likely to experience loneliness than siblings without the illness.

AIM: Our clinical observations raised concern that teenagers and young people with neurofibromatosis type 1 (NF1) might feel lonely and we decided to investigate their experiences and compare them with unaffected siblings. We also assessed predictive factors of loneliness. METHODS: We evaluated 60 NF1 patients aged 17 (±3.1) years and 23 siblings aged 17 (±2.9) years with a self-report questionnaire that assessed loneliness, depression, shyness, self-esteem, social support, bullying and difficulties making friends. Objective assessments of NF1 disease severity and visibility and somatic NF1-related and social support-related variables were carried out. Multiple linear regression analysis was performed. RESULTS: Of the 60 patients with NF1, 11 (18%; CI: 8-28%) said that they felt lonely often or always and felt a higher degree of loneliness, but none of the siblings said that they felt lonely. Predictors of loneliness were depression, shyness, bullying, self-perceived conception of illness burden and a low level of social support from friends. CONCLUSION: Teenagers and young adults with NF1 experienced a higher prevalence and higher degree of loneliness than siblings of NF1 patients. As loneliness affects social, affective and cognitive functions, increased attention on loneliness and the predictive factors described in this study are required.