Disclosure: A. Jin: None. A. Bryant: None. A. Bhatnagar: None. K. Soe: None.X-linked adrenoleukodystrophy (X-ALD) is a rare congenital neurodegenerative demyelinating disorder and primary adrenal insufficiency with variable presentations. The diagnosis can be delayed and easily missed especially among adults. We report a case of a 32-year-old African American male with adult-onset X-ALD presenting with primary adrenal insufficiency only and Marfanoid features. He was diagnosed with primary adrenal insufficiency of unknown etiology at the age of 22 when he was hospitalized with generalized weakness, dehydration and acute renal failure. He was able to maintain normal blood pressure and functionality by taking hydrocortisone only without fludrocortisone replacement. The patient was also noted to have marfanoid habitus. Further workup for primary adrenal insufficiency revealed negative 21-alpha-hydroxylase antibodies and elevated Very Long Chain Fatty Acids (VLCFA). Genetic testing showed the novel mutation of ABCD1 gene, p.His97Arg, confirming the diagnosis of X-ALD. Evaluation by ophthalmology, neurology and neuropsychiatry was insignificant, and he was found to have normal cognition and neurological function. MRI of the brain and the entire spine was unremarkable. No genetic testing for Marfanoid features was done, as there were no cardiac and eye findings to support the diagnosis of Marfan syndrome. The patient has no known family members with significant endocrine disorder and X-ALD genetic screening for his family is in progress. This case highlights the importance of considering X-ALD as a potential diagnosis and screening by checking VLCFA in the plasma in male patients with primary adrenal insufficiency without adrenal antibodies. This case is unique in the novel genetic mutation found on testing and association with marfanoid features. Even though X-ALD is rare, it should be considered as a possible etiology for primary adrenal insufficiency because of associated endocrinopathies, neurological deficits, and significant variations in clinical presentation. It is important to raise awareness among providers that diagnosis with measurement of VLCFA is commercially available. It is crucial to counsel patients that diagnosis can be difficult due to limitations in currently available genetic testing methodology, lack of genotype to phenotype correlation, and the possibility of unknown genetic variants with unpredictable prognosis and clinical course. It is imperative that this rare but consequential diagnosis be kept on the differential so that patients are offered appropriate testing and referrals for life or family planning. Though there is no definitive treatment apart from steroid supplementation in adrenal insufficiency and monitoring, patients should be counseled on sick day rules for steroids, medical alert bracelets for adrenal insufficiency, and hydrocortisone administration in emergencies, which may be life-saving.Presentation: Monday, July 14, 2025

Through international gene-matching efforts, we identified 10 individuals with ultrarare heterozygous variants, including 5 de novo variants, in BMAL1, a core component of the molecular clock. Instead of an isolated circadian phenotype seen with disease-causing variants in other molecular clock genes, all individuals carrying BMAL1 variants surprisingly share a clinical syndrome manifest as developmental delay and autism spectrum disorder, with variably penetrant sleep disturbances, seizures, and marfanoid habitus. Variants were functionally tested in cultured cells using a Per2-promoter driven luciferase reporter and revealed both loss-of-function and gain-of-function changes in circadian rhythms. The tested BMAL1 variants disrupted PER2 mRNA cycling, but did not cause significant shifts in cellular localization or binding with CLOCK. Conserved variants were further tested in Drosophila, which confirmed variant-dependent effects on behavioral rhythms. Remarkably, flies expressing variant cycle, the ortholog of BMAL1, also demonstrated deficits in short- and long-term memory, reminiscent of the highly prevalent developmental delay observed in our cohort. We suggest that ultrarare variants in the BMAL1 core clock gene contribute to a neurodevelopmental disorder.

INTRODUCTION/BACKGROUNDPhaeochromocytomas (PC) account for up to 5–25% of adrenal incidentalomas. Some PC patients, especially those with an adrenal incidentaloma, are asymptomatic and have normal blood pressure. The frequency of incidentally discovered normotensive phaeochromocytomas is increasing owing to better accessibility of imaging procedures. These tumours may be linked to certain genetic syndromes, such as Multiple Endocrine Neoplasia (MEN) type 2B, a rare condition caused by the RET proto-oncogene mutation, and includes a range of clinical manifestations such as phaeochromocytomas, medullary thyroid carcinoma and mucosal neuromas. CASEA 34-year-old female who had undergone total thyroidectomy for medullary thyroid carcinoma (MTC) was referred for an incidental right adrenal mass from CT staging. She had no paroxysms of headache or palpitations, no family history of MTC, pheochromocytoma and MEN-related diseases. She was normotensive. Physical examinations revealed mucosal neuromas on the tongue, buccal mucosa, lips, and eyelids. No marfanoid habitus present. Laboratory results showed normal serum calcium (2.57 mmol/L), but a 24-hour urine metanephrine was four times the upper limit of normal, along with borderline elevation of normetanephrines. The adrenal CT revealed an indeterminate right adrenal mass measuring 2 × 2 × 3 cm with peripheral calcifications suggesting pheochromocytoma. Left lymph node and carotid sheath biopsy were reported as features consistent with ganglioneuroma. The patient is scheduled for a right retroperitoneoscopic adrenalectomy. The unifying clinical presentations are consistent with MEN 2B Syndrome. However, genetic panel testing was not done due to financial constraints. CONCLUSIONThis case underscores the importance of considering genetic syndromes, such as MEN type 2B, in patients with incidental findings of pheochromocytomas, even when the patient is normotensive. Early diagnosis and genetic testing can help guide management, including surveillance for other tumours associated with MEN type 2B and early intervention. Further research is needed to explore the clinical presentation of pheochromocytomas in normotensive patients.

Aim: To highlight a rare presentation of homocystinuria in a pediatric patient, initially manifesting as venous thrombosis, and later diagnosed through multidisciplinary evaluation of systemic features. Case Presentation: A 10-year-old boy, born to third-degree consanguineous parents, presented with progressive right lower limb swelling, later involving the left limb. Doppler ultrasonography revealed thrombosis of the infrarenal inferior vena cava extending into the bilateral common and right external iliac veins, for which anticoagulation was initiated. There was no history of fever, trauma, or systemic illness. Two years later, he developed seizures. On examination, he was disoriented, with a tall stature (165 cm) and increased arm span (170 cm). Ophthalmologic evaluation revealed ectopia lentis of the left eye. In view of multisystem involvement—thrombosis, seizures, marfanoid habitus, and lens dislocation—homocystinuria was suspected. Serum homocysteine levels were markedly elevated, and genetic testing confirmed a pathogenic variant consistent with the diagnosis. Multidisciplinary management involving neurology and hematology teams was initiated. The patient has remained clinically stable and is under regular follow-up for the past three years. Conclusion: This case emphasizes the need to consider metabolic disorders such as homocystinuria in children with unexplained thrombotic and neurological symptoms. A high index of suspicion, combined with coordinated multidisciplinary care, is crucial for early diagnosis and improved long-term outcomes.

ContextPachydermoperiostosis (primary hypertrophic osteoarthropathy, PHO), usually due to biallelic loss of function variants in HPGD and SLCO2A1, has some features overlapping with acromegaly and is often referred to endocrinologists. A detailed endocrine assessment is not available for these patients.ObjectiveTo assess the genetic and endocrine characteristics of patients with PHO referred to endocrine centers with a possible diagnosis of acromegaly.MethodsSeventeen patients from 14 families in which acromegaly was excluded based on lack of elevated insulin-like growth factor (IGF)-1 levels and/or growth hormone suppression on an oral glucose tolerance test were assessed for HPGD and SLCO2A1 variants.ResultsAge at diagnosis was 26.2 ± 9.0 years (mean ± SD, range 9-43). Digital clubbing was present in all patients. Periostosis (94%), arthralgia (88%), periarticular edema (77%), pachydermia (82%), and coarsened facial features resembling acromegaly (71%) were present in the vast majority of the patients, while eyelash trichomegaly, blepharoptosis, high-arched palate, gingival hypertrophy, gastrointestinal symptoms, and marfanoid habitus were seen in some. Nine patients (53%) had low IGF-1 levels; the rest of the patients had IGF-1 levels in the lowest quartile of the reference range. Estradiol concentration was increased above the normal range in 8 male patients (62%) with normal testosterone and prolactin levels. Biallelic HPGD (2/14 kindreds) or SLCO2A1 (8 novel) variants (12/14 kindreds) were found. Two patients had no identifiable pathogenic/likely pathogenic variant in HPGD or SLCO2A1. Their phenotype was not different from the other patients.ConclusionWe establish that low IGF-1 and elevated estradiol levels are frequent features of PHO. Nine novel and 5 known pathogenic/likely pathogenic genetic variants were identified.

Multiple endocrine neoplasia type 2 syndrome (MEN2) is a hereditary disease resulting from mutations of the rearranged during transfection (RET) protooncogene subclassified into MEN2A [medullary thyroid carcinoma (MTC), pheochromocytoma, and primary hyperparathyroidism] and MEN2B (MTC, pheochromocytoma, Marfanoid habitus, mucous neuromas, and intestinal ganglioneuromatosis). Prophylactic thyroidectomy is recommended in RET-mutated patients. The age at which it should be performed depends on the type and aggressiveness of the mutation. This study aimed to evaluate the genotype/phenotype correlation and outcome in pediatric/adolescent carriers of MEN2 RET mutation. In a retrospective series of 23 carriers of RET MEN2 mutation who were ≤19 years old at diagnosis and had undergone total thyroidectomy ± lymphadenectomy, the following were analyzed: 1) specific RET mutation, 2) clinical and histopathological characteristics, 3) genotype/phenotype correlation, and 4) outcome at last follow-up. In our series, the female gender was more prevalent (F/M ratio 2.8/1), and the median age was 14.9 years [interquartile range (IQR) 12.6-17.2]. RET mutations were at very high risk in 4.3% of patients (M918T), high risk in 43.5% (C634), and moderate risk in 52.2% (47.8% C618 and 4.3% C620). All patients underwent surgery: at histology, MTC was found in 19/23 (82.6%) patients, C-cell hyperplasia in 2/23 (8.7%), and benign histology in 2/23 (8.7%). Ten patients (52.6%) had a disease event during the follow-up: 2/19 (10.5%) showed biochemical disease, 6/19 (31.6%) lymph node recurrences, and 2/19 (10.5%) distant metastases (50% liver, 50% bone). At the last follow-up, nine MTCs were not cured. One patient died after 9 years of follow-up at 21 years old (M918T RET+). From these data, it is clear to see the importance of genetic counseling and RET screening in all first-degree relatives of patients with proven MEN2. The goal should be to subject patients to surgery for prophylactic and not curative purposes, i.e., before the onset of MTC, given the high risk of persistent or recurrent disease also in pediatric/adolescent patients.

Marfan syndrome and related disorders describe a group of rare genetic diseases affecting connective tissue and characterised by cardiovascular, ocular and musculoskeletal manifestations. Marfan syndrome presents with a marfanoid habitus, ectopia lentis, dilatation of the aorta and typical musculoskeletal features. Other related disorders share similar characteristics. Loeys-Dietz syndrome distinguishes itself with generalized arterial tortuosities and aneurysms as well as, occasionally, hypertelorism and bifid uvula; patients with Beals syndrome have congenital articular contractures and craniofacial anomalies. Lujan-Fryns and Shprintzen-Goldberg syndromes, as well as homocystinuria, are often associated with intellectual disability.

Multiple endocrine neoplasia type 2B (MEN2B) is a rare autosomal dominant disorder caused by germline pathogenic RET variants. On the other hand, Charcot-Marie-Tooth disease (CMT) is a hereditary neurological disorder, characterized by distal muscle weakness and sensory loss, with approximately 100 identified causative genes. Herein, we report a de novo RET mutation in a patient presenting with clinical features of both MEN2B and CMT. The patient, a 22-year-old woman, had a history of lower limb muscle weakness, with no family history of MEN2B or CMT. The patient was being treated for a thyroid gland neoplasm. Genetic testing of the medullary thyroid carcinoma revealed a previously unreported RET germline variant, p.M918W (RET: c.2752_2753delinsTG, p.Met918Trp). The novel p.M918W RET variant was associated with concurrent MEN2B and CMT. This finding was unexpected as MEN2B typically manifests with distinct features, such as marfanoid habitus and mucosal neuromas, but not with muscle weakness, as seen in CMT. Based on this finding, the plausible role of the p.M918W mutation as a shared pathway for both MEN2B and CMT warrants further investigation.

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant hereditary cancer syndrome caused by germline variants in the REarranged during Transfection (RET) proto-oncogene. MEN2 is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. There are two clinically distinct types of MEN2 syndrome, termed MEN2A and MEN2B. MEN2A is associated with medullary thyroid carcinoma (MTC) and the less frequent occurrence of pheochromocytoma, primary hyperparathyroidism, or both, rarely with cutaneous lichen amyloidosis or Hirschsprung's disease. MEN2B is associated with MTC, pheochromocytoma, and other noncancerous abnormalities, such as Marfanoid habitus and ganglioneuromas of the intestines. Specific RET mutations suggest a predilection toward a particular phenotype and clinical course with strong genotype-phenotype correlation. Based upon these genotype-phenotype correlations, RET mutations are stratified into three risk levels, i.e., highest, high, and moderate risk, based on the age of onset and the penetrance of the MTC. Children in the highest risk category develop MTC within the first year of life and should undergo thyroidectomy in their first year, perhaps even in their first months of life. In children in the high-risk category, ultrasound of the neck and calcitonin (Ctn) measurement should be performed prior to thyroidectomy. Thyroidectomy should typically be performed at 5years of age or earlier, depending on the presence of elevated serum Ctn levels. However, heterogeneity in disease expression and progression within these groups varies considerably. To personalize disease management, the decision regarding the age of prophylactic thyroidectomy is no longer based upon genotype alone but is currently driven by additional clinical data, the most important being serum Ctn levels. In the moderate-risk group, the timing of thyroidectomy is particularly dependent on the Ctn level. Personalized management also includes decisions about the best age to begin biochemical screening for pheochromocytoma and primary hyperparathyroidism.

Spine deformity surgery in patients with Beals syndrome can be effectively performed but does risk revision surgery.

Variants in EFEMP1, encoding Fibulin-3, were previously reported as a rare cause of heritable connective tissue disorder (HCTD) with recurrent hernias and joint hypermobility. We report three new cases with biallelic or monoallelic EFEMP1 variants and severe hernia phenotypes. Two male siblings of 10 and 13 years old presented with marfanoid habitus, recurrent inguinal and umbilical hernias, generalized joint hypermobility, and scoliosis. Parents and halfsiblings reported joint hypermobility and umbilical hernias. The eldest boy died at age 16 from incarcerated gastrointestinal herniation complicated by gastric and bowel necrosis with perforation. Autopsy revealed widespread intestinal diverticula. Immunohistochemistry of skin and fascia tissue did not reveal any abnormalities, including normal staining of elastic fibers. Both siblings harbored compound heterozygous likely pathogenic EFEMP1 variants (c.1320 + 2T > A, p.? and c.698G > A, p.Gly233Asp). An unrelated 58-year-old male had marfanoid features, high myopia, recurrent diaphragmatic and inguinal hernias, and chronic gastrointestinal dilatation with severe malabsorption. Both his dizygotic twin-brother and mother had recurrent hernias and high myopia. This man died at 59 years of age, and autopsy showed extensive diaphragmatic herniation, bowel diverticula, and pulmonary emphysema. A heterozygous EFEMP1 splice-variant (c.81 + 1G > A, p.?) was identified, causing exon skipping leading to a start-loss. Targeted genome reanalysis nor RNA-sequencing revealed a second variant at the other allele. The reported individuals expand the clinical and pathological phenotypes of EFEMP1-related disease, a distinct entity within the spectrum of HCTD. The severe and recurrent hernias, gastrointestinal dilatation, and diverticulosis result in an increased risk for life-threatening complications, demanding early recognition and close monitoring.

Abstract Disclosure: R. Ghosh: None. N. Behiri: None. J. Glod: None. S. Gubbi: None. J. Klubo-Gwiezdzinska: None. Background: Multiple endocrine neoplasia (MEN) syndromes are autosomal dominant and present with tumors in at least two or more endocrine organs. MEN2 syndromes that are driven by germline rearranged during transfection (RET) gene pathogenic variants are divided into 2A consisting of medullary thyroid carcinoma (MTC), parathyroid adenomas and pheochromocytoma and 2B presenting with MTC, pheochromocytoma, marfanoid habitus, mucosal neuromas and gastrointestinal ganglioneuromatosis. Pituitary adenomas have been rarely described in MEN2 and hence we conducted a retrospective chart review to determine their prevalence in MEN2. Methods: Retrospective chart screening of MEN2 patients followed at a tertiary referral center between August 1999- August 2022 was done to evaluate the prevalence of pituitary adenomas using biochemical hormonal evaluation and magnetic resonance imaging (MRI) of pituitary based on screening of clinical symptoms. Results: The study consisted of 91 patients (43 MEN2A and 48 MEN2B), aged 35.3±16.9 years (MEN2A) and 18.6±6.4 years (MEN2B), 20/43 (46.5%) women in MEN2A and 24/48 (50%) women in MEN2B. These patients were followed for median duration of 6.5 years (3.3-22) in MEN2A and 8.5 years (5.4-14.6) in MEN2B. RET mutation status was unavailable for 1 MEN2A patient out of 91 patients. Among MEN2A patients, majority (53.5%) were positive for RET C634X mutation followed by RET 804, 609, 631,620 and 666 mutations in the descending order. While in MEN2B cohort all patients were positive for M918T RET mutation. A total of 4/91 (4.4%) patients were found to have pituitary adenomas (3 MEN2B and 1 MEN2A). One patient had clinically symptomatic ACTH producing microadenoma which was surgically resected, and others have asymptomatic non-functioning adenomas. The patient with Cushing’s disease underwent three transsphenoidal resections leading to complete resolution but developed panhypopituitarism. Prevalence of pituitary adenomas in our cohort was significantly higher than the general population screened based on clinical suspicion (p<0.001). Conclusion: Prevalence of clinically symptomatic pituitary adenomas is 1 in 1000 in the general population (1). It is rarely associated with MEN2 syndromes and only few cases are reported in the literature (2). However, screening of all patients with MEN2 for pituitary adenomas, regardless of clinical suspicion, might lead to incidental discovery of asymptomatic pituitary pathology and can provide the actual prevalence. Further studies are needed to evaluate the genetics of these pituitary adenomas in MEN2 syndromes to investigate whether RET protooncogene is indeed the dominant molecular driver of these tumors.

Recent investigations on familial thoracic aortic aneurysm and dissection (TAAD) identified several genetic variants. Meanwhile, intracranial vasculopathy in familial TAAD has been scarcely reported. We report a case of a young man with Marfanoid habitus and familial TAAD carrying MFAP5, c.472C>T variant. He presented with recurrent thunderclap headache and multifocal intracranial vasculopathy, which is predominantly suggestive of reversible cerebral vasoconstriction syndrome. While the role of MFAP5 in vasculopathy requires clarification, we propose its haploinsufficiency may contribute to both TAAD and intracranial stenosis, highlighting a potential risk of cerebrovascular disease in familial TAAD.

Biallelic mutations in UBE3B cause Kaufman oculocerebrofacial syndrome (KOS; OMIM 244450) with a wide range of clinical manifestations. In this study, we employed genetic analyses including homozygosity mapping, candidate gene sequencing, whole exome sequencing, and confirmatory Sanger sequencing on eight patients from three unrelated consanguineous families. Our analysis yielded three different novel variants in UBE3B : a missense substitution [NM_130466.4: c.2975C>T; (p.Pro992Leu)] in the HECT domain in family 1, a 3-bp deletion within exon 14 [c.1692_1694delCTC; (p.Ser565del)] leading to removal of a serine residue in family 2, and a splice donor site variant in intron eight of UBE3B (c.630 + 1G>T) in family 3. Blepharophimosis, telecanthus, ptosis, intellectual disability and abnormal lipid profile were similar to those found in previously reported KOS patients. Longitudinal follow-up revealed rather marfanoid body habitus of the patients in family 1. This study reports eight patients from Saudi Arabia with novel deleterious variants in UBE3B and adds to the phenotypic spectrum of KOS.

Congenital contractual arachnodactyly (CCA) is a genetic connective tissue disorder that is characterized by arachnodactyly, kyphoscoliosis, marfanoid habitus, and crumpled ears. We report a case of a boy with suspected Marfan syndrome. Genetic analysis revealed c.3207_3217+9del in a heterozygote form of the fibrillin-2 (FBN2) gene. This patient was diagnosed with CCA based on his phenotype, and the pathogenicity of this variant was classified according to cDNA analysis and protein modeling.

Marfan Syndrome (MFS) is an autosomal dominant disease caused in most cases by mutations in the FNB1 gene, which encodes for fibrillin 1. MFS does not alway shows typical phenotypic signs. Indeed, the occurrence of sudden death of unknown cause is increasingly seen in young adults without ante mortem preexisting pathology to explain the event. In many cases the diagnosis of Marfan Syndrome (MFS) is carried out post mortem, especially in cases where the disease’s external phenotype is absent. Here is reported a case of a young woman who died during a twin pregnancy investigated with medico-legal and forensic anthropological procedures. The autopsy showed the absence of a typical marfanoid habitus and the presence of a dissecting aneurysm of the aorta with histopathological degeneration of the aortic elastic fibers. The genetic investigation revealed two previously undetected de novo mutations of the FBN1 gene: c.T6181C: p.C2061R and c.G1415A: p.C472Y. This new mutations, together with a comprehensive analysis, demonstrates the existence of a causal relationship between these mutations and the dissecting aneurysm of the aorta. This also stresses the importance of a combined multidisciplinary approach to this condition which includes morphological and genetic studies.

Aortic dissection (AD) is a medical emergency with a poor prognosis if not recognized early and treated promptly. In this setting, clinical data may be equivocal, while electrocardiogram, laboratory tests, and chest radiography often show nonspecific findings. In contrast, cardiac point of care ultrasound (POCUS) has proven useful in the diagnosis and detection of complications of AD. We present the case of a 29-year-old man with marfanoid habitus presenting with chest pain and acute heart failure, in whom cardiac POCUS aided in the rapid diagnosis of type A AD and pulmonary edema. POCUS contributed to optimizing the medical treatment and allowed for early activation of the surgical team.

Abstract Disclosure: R. Ghosh: None. G. Al-Naqeeb: None. P. Veeraraghavan: None. C. Craig: None. J. Klubo-Gwiezdzinska: None. S. Gubbi: None. Background: Germline pathogenic variants in the RET protooncogene give rise to multiple endocrine neoplasia (MEN) types 2A and 2B. MEN2A is mainly characterized by MTC (∼100%), pheochromocytoma (PHEO; 4% - 88%), and primary hyperparathyroidism (HPTH; 2% - 30%), while MEN2B predominantly manifests with MTC (100%), PHEO (50%), mucocutaneous neuromas, and marfanoid habitus. Both MEN2A and 2B follow an autosomal dominant mode of inheritance. While certain pathogenic RET variants (M918T, A883F, and C634X) have high penetrance and present with aggressive disease, other variants such as V804M are of low penetrance and manifest with clinically mild disease.Clinical case: A 75-year-old male was referred to our center for further evaluation of the finding of an abnormal RET gene that was identified on a peripheral blood whole-exome gene sequencing research panel performed at an outside center. The patient was noted to have a germline RET c.2410 G>A, p.V804M heterozygous pathogenic variant. The patient denied any history of lump in the neck, symptoms of hyper- or hypothyroidism, tremors, headaches, fatigue, facial flushing, palpitations, constipation, diarrhea, anxiety, depression, or history of fragility fractures. Medical history consisted of hypertension, nephrolithiasis, type 2 diabetes mellitus, obstructive sleep apnea, interstitial pulmonary fibrosis, and colonic diverticula and polyps. Family history was significant for leukemia, colon, and breast cancers, but none of the relatives had a history of MTC, PHEO, or MEN2, and his children, while healthy, had not undergone RET germline testing. Physical examination showed no evidence of hypothyroidism or hyperthyroidism. Neck examination showed no evidence of thyromegaly or cervical lymphadenopathy. Laboratory investigations were unremarkable [serum calcitonin: 7.9 pg/ml (NL: </=14.3), CEA 2.8 mcg/L (NL: 0.8-3.4), thyrotropin (TSH): 1.92 microIU/ml (NL: 0.35-4.94), free thyroxine: 0.9 ng/dl (NL: 0.7-1.5), plasma free normetanephrine: 0.31 nmol/L (NL: <0.9), plasma free metanephrines 0.24 nmol/L (NL: <0.5), parathyroid hormone: 28.2 pg/ml (NL: 15-65), and ionized calcium 1.23 mmol/l (NL: 1.09-1.30)]. Thyroid sonogram was normal. We recommended active annual surveillance with biochemical markers and imaging along with genetic testing of the RET gene in his children. Conclusion: The V804M RET variant has been often associated with MTC or MEN2A phenotypes [1]. However, the variable expression of this variant may lead to a mild clinical phenotype or even absence of MTC/MEN2A manifestations. Hence, active surveillance as opposed to radical surgery like prophylactic thyroidectomy would be more beneficial in patients with no clinical or biochemical evidence of disease. Reference: Pinna et al., 2007, V804M is the most frequent mutation and may be associated with FMTC/MEN-2A phenotype. Thyroid, 17(2), 101-104. Presentation Date: Saturday, June 17, 2023

Abstract Disclosure: D.J. Gomez D' Aza: None. M. Kasap: None. T. Zahedi: None. F. Zhang: None. Introduction: Multiple endocrine neoplasia (MEN) syndromes are rare autosomal dominant inherited groups of disorders characterized by the presence of two or more primary endocrine glands tumors. MEN type 1 is usually associated with neoplastic lesions of the pituitary gland, the parathyroid gland, and the pancreas. MEN type 2 typically presents with overgrowth of parathyroid, adrenal glands (pheochromocytoma), and parathyroid hyperplasia (MEN 2A), Marfanoid body habitus, or mucosal neuromas (MEN 2B). It can also manifest with non-endocrine tumors including carcinoid tumors, adrenocortical tumors, meningiomas, facial angiofibromas, collagenomas, lipomas, and germline mutations (MEN type 4). It is extremely rare for MEN type 1 syndrome to have concomitant pheochromocytoma. Case Report: We present a case of a 69 yo female with multiple comorbidities who was hospitalized for heart failure exacerbation. CT scan showed incidental findings of a 4.1 cm right adrenal nodule, a 2.1 cm left anterior mediastinum nodule, and a 1.1 cm oval pituitary mass. She had multiple episodes of hypertension urgency during the last two years. After patient recovered to her base line, workup labs revealed elevated serum Catecholamine with Metanephrine 431.1 pg/mL, Normetanephrine 466.5 pg/mL, Norepinephrine 137 pg/mL, and high PTH 258 pg/mL. Further study was normal for pituitary function tests, aldosterone, renin, cortisol, thyroid, and renal function. PET scan showed mild hypermetabolic activity in bilateral adrenal glands without any abnormal hypermetabolic activity in the chest. Thyroid Ultrasound identified a 1 cm thyroid nodule. Phenoxybenzamine was started due to concern for pheochromocytoma. Patient was monitored closely since she declined surgical intervention. Discussion: MEN syndromes have variable clinical presentation with multiple hormone excess. This patient has imaging and laboratory findings highly suggestive of MEN syndrome with pituitary adenoma, pheochromocytoma, and hyperparathyroidism. Further work up and genetic testing would be helpful to identify the mutation of MEN type 1 or type 2. Clinicians should be aware of the variable presentation of MEN syndrome, and prompt treatment is warranted to prevent life-threatening conditions. Presentation: Friday, June 16, 2023

Classical homocystinuria is caused by pathogenic variants in the CBS gene leading to a deficiency of the vitamin B6-dependent enzyme cystathionine beta synthase. The disease is typically associated with high blood homocysteine concentrations. Clinical features include developmental delay/intellectual disability, psychiatric problems, thromboembolism, lens dislocation, and marfanoid habitus. We report on a child with classical homocystinuria presenting with acute episodes of dystonia and symmetrical basal ganglia abnormalities mimicking a mitochondrial disease. After starting treatment with vitamin B6, homocysteine levels rapidly normalized and dystonic episodes did not re-occur. Moreover, brain-imaging findings almost completely disappeared. The case illustrates that homocystinuria should be considered as a treatable differential diagnosis of dystonia.