Babovic‐Vuksanovic, Dusica

Abstract The pre‐mRNA‐processing factor 8, encoded by PRPF8, is a scaffolding component of a spliceosome complex involved in the removal of introns from mRNA precursors. Previously, heterozygous pathogenic variants in PRPF8 have been associated with autosomal dominant retinitis pigmentosa. More recently, PRPF8 was suggested as a candidate gene for autism spectrum disorder due to the enrichment of sequence variants in this gene in individuals with neurodevelopmental disorders. We report 14 individuals with various forms of neurodevelopmental conditions, found to have heterozygous, predominantly de novo, missense, and loss‐of‐function variants in PRPF8 . These individuals have clinical features that may represent a new neurodevelopmental syndrome.

AbstractNeurofibromatosis type 1 (NF1) is a common neurocutaneous disorder characterized by development of pigmentary skin changes, neurogenic tumors, and other manifestations involving multiple organ systems. Penetrance is complete, though expressivity is quite variable even among the family members. Given that NF1 is a common hereditary condition, existence of a second genetic disorder in NF1 patients is not unexpected. During comprehensive evaluations of individuals with NF1, we encountered 11 patients with dual diagnosis who contributed to phenotypic complexity and challenges for long‐term management. Examples include Prader–Willi Syndrome, Autosomal Dominant Polycystic Kidney Disease, Down syndrome, infantile myofibromatosis, Craniosynostosis, cleft lip and palate, 47,XYY, 22q11.2 duplication, 15q13.3 deletion syndrome, and BRCA2‐ and ATM‐ related cancer predisposition syndromes. Presence of dysmorphism, developmental delay, atypical tumors, and family history of other genetic disorders including cancers appears as determinants to consider a second genetic etiology and helps to differentiate from an extreme phenotypic spectrum of NF1. Clinicians should have high index of suspicion to exclude coexisting disorders, as apart from providing comprehensive medical care. This also has potential implications in genetic counseling. Long‐term effects of the synergistic mechanisms leading to phenotypic complexity and patient outcomes are yet to be characterized, with follow‐up needed.

AbstractBiallelic loss‐of‐function variants in the thrombospondin‐type laminin G domain and epilepsy‐associated repeats (TSPEAR) gene have recently been associated with ectodermal dysplasia and hearing loss. The first reports describing a TSPEAR disease association identified this gene is a cause of nonsyndromic hearing loss, but subsequent reports involving additional affected families have questioned this evidence and suggested a stronger association with ectodermal dysplasia. To clarify genotype–phenotype associations for TSPEAR variants, we characterized 13 individuals with biallelic TSPEAR variants. Individuals underwent either exome sequencing or panel‐based genetic testing. Nearly all of these newly reported individuals (11/13) have phenotypes that include tooth agenesis or ectodermal dysplasia, while three newly reported individuals have hearing loss. Of the individuals displaying hearing loss, all have additional variants in other hearing‐loss‐associated genes, specifically TMPRSS3, GJB2, and GJB6, that present competing candidates for their hearing loss phenotype. When presented alongside previous reports, the overall evidence supports the association of TSPEAR variants with ectodermal dysplasia and tooth agenesis features but creates significant doubt as to whether TSPEAR variants are a monogenic cause of hearing loss. Further functional evidence is needed to evaluate this phenotypic association.

Introduction Germline predisposition syndromes (GPS) are inherited disorders associated with germinal aberrations that increase the risk of malignancies. While aberrations in certain genes increase the risk for all types of malignancies (Tp53, ATM, CDKN2A, CHEK2), there is a growing list of genes associated specifically with hematological malignancies (GATA2, RUNX1, DDX41, ETV6, ANKRD26). At our institution, we have established a hematology GPS clinic to diagnose and manage GPS and with this report, detail our experience with 130 patients. Methods GPS were investigated in pediatric and adult patients with one or more first degree relatives with hematological/visceral malignancies or in those with antecedent thrombocytopenia (ANKRD26, RUNX1, ETV6), or with specific syndromic features (short telomere syndromes/STS, GATA2 haploinsufficiency, Fanconi anemia/FA, Shwachman-Diamond syndrome/SDS). Depending on the phenotype, specific functional assays such as flow-FISH for telomere length assessment and chromosomal breakage assays were ordered. After informed consent and genetic counselling, germline testing was carried out on peripheral blood mononuclear cell, skin fibroblast, or hair follicle-derived DNA. A custom-designed marrow failure NGS panel (200 genes) was used in most cases and interrogation of variants, in silico studies, and functional assays were carried out as previously described (Mangaonkar et al MC Proc 2019). Copy number variations were identified by aCGH. At the time of progression/worsening cytopenias, bone marrow/lymph node biopsies and NGS (next generation sequencing) were carried out where indicated. Results 130 patients with germline predisposition have been identified to date. The spectrum of disorders seen include STS 29 (22%), FA 17 (13%), GATA2 16 (12%), Diamond Blackfan anemia/DBA 13 (10%), RUNX1-FPD 12 (9%), ATM deletions/mutations 11 (8%), ANKRD26 6 (5%), SDS 5 (4%), DDX41 4 (3%), MPL 3 (2%), CHEK2, MECOM, Tp53 mutations 2 (2%) each, and CBL, CEPBA, ELANE, NF1, CDKN2A, CSF3R, ETV6, and GATA1 mutations, 1 (1%) each. Evidence for clonal evolution (CCUS) and hematological malignancies were seen in 51 (39%) patients, involving all the aforementioned genes/syndromes with the exception of DBA, CBL, ETV6, MPL, CSF3R, and GATA1. Seven (64%) of 11 patients with germline ATM deletions/mutations developed lymphoid malignancies; homozygous ATM (Follicular NHL-1, Burkitt lymphoma-1, T-ALL-1, T-LPD-1) and heterozygous ATM (T-PLL-1, DLBCL-1, CLL-1). Clonal evolution occurred in 11 (69%) of 16 GATA2 haploinsufficient patients (CCUS-2, MDS-3, CMML-1, AML-5) and in 7 (58%) of 12 RUNX1-FPD patients (CCUS-1, MDS-1, MDS/MPN-3, AML-2). Five of 29 (17%) STS patients had clonal progression (CCUS-2, MDS-2, AML-1), and 5 (29%) of 17 FA patients progressed to MDS-2 or AML-3. JMML was seen in one patient with a germline NF1 mutation, while 1 (20%) of 5 SDS patients progressed to AML. NGS data at progression was available in 24 (55%) of 44 myeloid/CCUS progressions, with somatic truncating ASXL1 mutations being most frequent (29%), followed by RAS pathway mutations (15%). AML/MDS progressions in STS, FA, and SDS were universally associated with complex/monosomal karyotypes, translating to refractory disease. Seventeen (39%) of 44 patients with myeloid predisposition underwent allogenic HCT (GATA2-7, FA-3, RUNX1-FPD-3, STS-2, NF1-1, Tp53-1), with 10 (59%) being alive at last follow up (Table 1). Conclusion We demonstrate the spectrum of germline aberrations associated with predisposition to hematological malignancies and outline the phenotypic heterogeneity of clonal transformation. The advent of NGS allows identification of clonal progression earlier than morphological changes, with mutations in ASXL1 and RAS pathway genes being commonly implicated. This study supports the universal development of dedicated germline predisposition clinics. Disclosures Pruthi: CSL Behring: Honoraria; Genentech Inc.: Honoraria; Bayer Healthcare: Honoraria; HEMA Biologics: Honoraria; Instrumentation Laboratory: Honoraria; Merck: Honoraria.

AbstractObjectiveComprehensive data about patients with bilateral pheochromocytoma are limited. We aimed to describe the clinical presentation, genetic analysis, treatment and outcomes of patients with bilateral pheochromocytoma.DesignA retrospective study at a tertiary care centre.PatientsAll patients with bilateral pheochromocytoma evaluated at Mayo Clinic in Rochester, Minnesota between January 1951 and December 2015.MeasurementsTumour size, genetic testing, plasma/urine metanephrines and catecholamines.ResultsA total of 94 patients (51% women) were diagnosed with bilateral pheochromocytoma at a median age at first presentation of 31 years (range, 4‐70). Bilateral disease was noted in 8.0% of pheochromocytoma patient overall and 37.5% of patients 18 years of younger. Most patients presented with synchronous tumours (80%). Median time to metachronous tumours was 4.5 years (range, 1‐38). Genetic disease was identified in 75 (80%) patients, including MEN 2A (42.6%), VHL (19.1%), MEN 2B (9.6%) and NF1 (8.5%). Excess catecholamines were present in 97% of patients. Patients with synchronous pheochromocytoma commonly underwent simultaneous bilateral adrenalectomy (99%), and 18 (24%) had cortical‐sparing surgery. Multicentric tumours were reported in 23 of 77 (30%) patients with available data. Recurrent disease was found in 9.6% of patients, and 8.5% developed metastatic disease. Median follow‐up was 8.5 years. At the study conclusion, 4 patients had died due to pheochromocytoma or adrenalectomy.ConclusionsBilateral pheochromocytoma occurred in 7.0% of adults with pheochromocytoma and 37.5% of paediatric patients. Genetic disease was identified in 80% of patients, predominantly MEN2A. Multicentric tumours were common, but most were still cured following adrenalectomy.

Abstract SPECC1L mutations have been identified in patients with rare atypical orofacial clefts and with syndromic cleft lip and/or palate (CL/P). These mutations cluster in the second coiled-coil and calponin homology domains of SPECC1L and severely affect the ability of SPECC1L to associate with microtubules. We previously showed that gene-trap knockout of Specc1l in mouse results in early embryonic lethality. We now present a truncation mutant mouse allele, Specc1lΔC510, that results in perinatal lethality. Specc1lΔC510/ΔC510 homozygotes showed abnormal palate rugae but did not show cleft palate. However, when crossed with a gene-trap allele, Specc1lcGT/ΔC510 compound heterozygotes showed a palate elevation delay with incompletely penetrant cleft palate. Specc1lcGT/ΔC510 embryos exhibit transient oral epithelial adhesions at E13.5, which may delay shelf elevation. Consistent with oral adhesions, we show periderm layer abnormalities, including ectopic apical expression of adherens junction markers, similar to Irf6 hypomorphic mutants and Arhgap29 heterozygotes. Indeed, SPECC1L expression is drastically reduced in Irf6 mutant palatal shelves. Finally, we wanted to determine if SPECC1L deficiency also contributed to non-syndromic (ns) CL/P. We sequenced 62 Caucasian, 89 Filipino, 90 Ethiopian, 90 Nigerian and 95 Japanese patients with nsCL/P and identified three rare coding variants (p.Ala86Thr, p.Met91Iso and p.Arg546Gln) in six individuals. These variants reside outside of SPECC1L coiled-coil domains and result in milder functional defects than variants associated with syndromic clefting. Together, our data indicate that palate elevation is sensitive to deficiency of SPECC1L dosage and function and that SPECC1L cytoskeletal protein functions downstream of IRF6 in palatogenesis.

INTRODUCTION: Loey Dietz syndrome (LDS) is an autosomal dominant disorder caused by a mutation in TGFBR1 - or TGFBR2. LDS is characterized by distinctive facies, tortuous arteries and aortic aneurysms predisposition to eosinophilic allergic disorders including eosinophilic esophagitis and gastritis, and other systemic findings including inflammatory bowel disease. Patients with vascular Ehlers Danlos Syndrome (vEDS) have deficiency in type III collagen and have similar vascular laxity and concomitant GI manifestations. This connective tissue vulnerability contributes to increased post-operative wound dehiscence and development of hernias. Our aim was to summarize abdominal wall and GI tract manifestations in these two rare vascular disorders at a tertiary referral center. METHODS: Data were collected via Advanced Cohort Explorer (ACE) application at Mayo Clinic. A chart review was undertaken on patients with a confirmed diagnosis of vEDS or LDS seen at Mayo Clinic in Rochester from 1994 to 2018. Diagnoses were confirmed by genetic testing and/or clinical review through the specialized medical genetics clinic. Information was extracted on vascular complications of disease, prevalence of abdominal hernias, and gastrointestinal symptoms. The study was reviewed and exempted by the Mayo Clinic IRB. RESULTS: We identified and reviewed records of 50 vEDS and 13 LDS patients; data are summarized in Tables 1 and 2. Patients were similar in age at diagnosis and gender distribution. Hernias were present in similar proportions of patients with vEDS and LDS, although ventral hernias were more frequent and the hernias were more likely to be post-operative in vEDS than in LDS. LDS patients had more aneurysms (58% vEDS vs. 76.9% LDS, P = 0.02) with higher proportion requiring arterial repair (32.7% vEDS vs. 69.2% LDS, P = 0.03). Co-morbidities more prevalent in LDS than vEDS were autonomic dysfunction, psychopathology and allergy. We did not note increase in symptoms suggestive of eosinophilic esophagitis/gastritis in the LDS patients. GI symptoms were prevalent in both disorders and largely similar, except for diarrhea and constipation which were both significantly more prevalent in LDS patients. CONCLUSION/DISCUSSION: While vEDS and LDS are both connective tissue disorders with propensity for GI symptoms, abdominal hernias and aneurysm formation, the risk of arterial rupture and co-morbidity of autonomic dysfunction, psychopathology and allergy are greater in LDS than vEDS.

Background Turner syndrome ( TS ) is the most common sex chromosome abnormality in women and is associated with increased morbidity and mortality. We describe long‐term outcomes in a large cohort of patients with TS . Methods and Results Retrospective review of patients with TS followed at Mayo Clinic Rochester from 1950 to 2017 was performed. Clinical, imaging, surgical, and genetic data were analyzed. Survival analysis was performed with the Kaplan–Meier method using age‐ and sex‐matched Olmsted County residents as the reference group. The study cohort comprised 317 patients with TS . Average age at diagnosis was 9 (range, 2–12) years, genetic testing was performed in 202 (64%), and pure monosomy X was present in 75 (37%). Congenital heart disease occurred in 131 (41%), with the most frequent lesions being bicuspid aortic valve (n=102, 32%) and coarctation of the aorta (n=43, 14%). Ascending aortic dilation was common, with mean aortic root size index 2 cm/m 2 , and aortic dissection occurred in 6 (2%) patients. The average follow‐up was 11 (range, 2–26) years, yielding 3898 patient‐years, and during this period 46 (14%) patients died; mean age at the time of death was 53±17 years. Patients with TS had reduced survival compared with the control group (82% versus 94% at 30 years; P <0.001), and the leading causes of death were cardiovascular disease, liver disease, and malignancy. Conclusions Patients with TS have reduced survival compared with age‐matched controls, and cardiovascular disease is the major cause of death. Further studies are required to determine if targeted cardiovascular risk factor modification will result in improved survival in this population.

Introduction: Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a multisystemic mitochondrial disorder that usually presents in childhood. Patients can have a wide array of neurological symptoms when presenting with stroke-like episodes, and imaging characteristics during the episodes can overlap with different neurological disorders. Case Report: A 61-year-old woman presented with communication difficulties consistent with auditory agnosia and was found to have bitemporal abnormalities on imaging that first raised the concern for herpes simplex virus encephalitis. Further work-up, in conjunction with the patient’s past medical and family history, suggested a mitochondrial disorder. Mitochondrial full genome analysis revealed m.3243A>G variant in the MT-TL1 gene, with 6% heteroplasmy in blood leading to a diagnosis of MELAS. Conclusions: MELAS is a disorder with clinical variability. Neuroimaging studies during stroke-like episodes in MELAS can provide significant clues to the underlying disorder. Although patients typically present in childhood, the first stroke-like episode can occur later in life in some patients, potentially related to a lower heteroplasmy level.