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Alzheimer disease is the most common cause of dementia in older adults. It is characterized by progressive memory loss, cognitive decline, and impaired daily functioning. Pathology shows extracellular beta-amyloid plaques and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. Parkinson disease causes dementia in some cases but with prominent motor symptoms first. Frontotemporal dementia causes early personality and behavior changes with frontal/temporal lobe atrophy. Lewy body dementia causes dementia with visual hallucinations and Parkinsonism, with alpha-synuclein inclusions. Alzheimer risk factors include advanced age, family history, APOE4 allele, and Down syndrome (extra APP gene on chromosome 21). Treatment includes cholinesterase inhibitors (donepezil, rivastigmine) and memantine.

This presentation is classic for Tay–Sachs disease, an autosomal recessive lysosomal storage disorder caused by deficiency of hexosaminidase A, leading to GM2 ganglioside accumulation. Features include neurodegeneration, developmental delay, hypotonia, exaggerated startle, and cherry-red spot on macula without hepatosplenomegaly. Niemann–Pick disease (sphingomyelinase deficiency) also presents with cherry-red spot but includes hepatosplenomegaly. Fabry disease (α-galactosidase A deficiency) causes angiokeratomas, neuropathy, and renal failure. Gaucher disease (glucocerebrosidase deficiency) causes hepatosplenomegaly, bone pain, and cytopenias. Tay–Sachs has no curative treatment; supportive care is provided. Genetic counseling is critical for prevention in high-risk populations.

The triad of primary hyperparathyroidism (kidney stones), gastrinoma/peptic ulcer disease (Zollinger–Ellison syndrome), and pituitary adenoma suggests Multiple Endocrine Neoplasia type 1 (MEN1). MEN1 results from inactivating mutations in the MEN1 tumor suppressor gene on chromosome 11, which encodes menin. Clinical manifestations include the “3 Ps”: parathyroid adenomas, pancreatic endocrine tumors (gastrinoma, insulinoma, glucagonoma), and pituitary adenomas (prolactinoma most common). RET proto-oncogene mutations are seen in MEN2A/2B, which feature medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism (MEN2A). VHL gene mutations cause von Hippel–Lindau disease, characterized by hemangioblastomas, renal cell carcinoma, and pheochromocytomas. TP53 mutations are implicated in Li-Fraumeni syndrome with diverse sarcomas and breast cancers. Recognition of MEN1 guides screening, genetic counseling, and surveillance of at-risk relatives.

Placenta previa occurs when the placenta implants over or near the cervical os. It presents with painless third-trimester bleeding and a soft, non-tender uterus. Placental abruption presents with painful bleeding, uterine tenderness, and fetal distress. Vasa previa causes painless bleeding at rupture of membranes with fetal bradycardia due to fetal vessel rupture. Uterine rupture causes painful bleeding, abnormal uterine contour, and loss of fetal station. Diagnosis of placenta previa is confirmed by transabdominal or transvaginal ultrasound. Vaginal exams should be avoided due to risk of hemorrhage. Management includes pelvic rest, cesarean delivery at term, and hospitalization if bleeding is recurrent or severe.

Acute pancreatitis is diagnosed with two of three criteria: typical abdominal pain, elevated amylase/lipase, and imaging findings. The most common causes are gallstones and chronic alcohol use. The initial management is supportive with aggressive IV hydration (to prevent hypovolemia from third spacing), bowel rest (NPO), and pain control. Antibiotics are not routinely indicated unless infected necrosis is confirmed. ERCP is indicated if pancreatitis is due to gallstones with biliary obstruction or cholangitis. Parenteral nutrition is unnecessary unless prolonged inability to tolerate oral intake; early enteral feeding is preferred if possible. Complications include pseudocyst, necrosis, ARDS, and shock. Prompt supportive care is key to improving outcomes.