A 10-year-old male presents with short stature, a round face, and brachydactyly. His labs are normal, with a serum calcium of 9.5 mg/dL, phosphorus of 4.5 mg/dL, and a slightly elevated parathyroid hormone (PTH). His father has a similar phenotype. What is the most likely diagnosis?
A 1-month-old infant with poor feeding and intermittent seizures is found to have a serum calcium of 6.2 mg/dL and a serum magnesium of 0.8 mg/dL. An intact parathyroid hormone (PTH) level is inappropriately low for the degree of hypocalcemia. Administration of intravenous calcium provides only transient improvement. What is the most likely underlying mechanism for this infant’s condition?
A 12-year-old boy is evaluated for moderate hypertension discovered on a school screening. His father and paternal grandmother both had strokes before age 40. The boy is normokalemic. Laboratory testing reveals elevated plasma aldosterone with suppressed plasma renin activity. Administration of dexamethasone leads to rapid normalization of his blood pressure and aldosterone levels. What is the underlying genetic cause of his condition?
A newborn with a 46,XY karyotype presents with atypical genitalia, including a small phallus, a bifid scrotum with perineal hypospadias, and a blind vaginal pouch. Müllerian structures are absent, but Wolffian structures like the epididymis and vas deferens are present. This patient is expected to undergo significant virilization at puberty. What is the most likely diagnosis?
A 6-year-old boy is diagnosed with type 1 diabetes mellitus. His 8-year-old asymptomatic sister undergoes genetic screening. Which of the following HLA haplotypes would confer the most dramatically protective effect against developing type 1 diabetes mellitus for the sister?
A 2-month-old infant with a 46,XY karyotype has normal male external genitalia but bilaterally nonpalpable testes. To differentiate between cryptorchidism and congenital anorchia, an hCG stimulation test and basal hormone levels are obtained. Which set of findings would confirm a diagnosis of congenital anorchia (vanishing testes syndrome)?
A 14-year-old female undergoes a near-total thyroidectomy for a 2 cm thyroid nodule. Pathology confirms papillary thyroid carcinoma. Genetic analysis of the tumor is performed. Which genetic finding is more commonly associated with pediatric papillary thyroid cancer compared to its adult counterpart?
A 12-year-old male is incidentally found to have a serum calcium of 11.8 mg/dL on routine labs. He is asymptomatic. Further workup reveals a parathyroid hormone (PTH) level that is inappropriately normal, a mildly elevated serum magnesium, and a decreased calcium-to-creatinine clearance ratio. His mother has a history of mild, asymptomatic hypercalcemia. What is the most likely diagnosis?
A term newborn with a 46,XX karyotype has clitoral hypertrophy, a urogenital sinus, and a uterus and ovaries on ultrasound. 17-hydroxyprogesterone and electrolytes are normal. The mother developed progressive hirsutism and voice deepening during pregnancy that resolved after delivery. What is the most likely diagnosis?
A 7-year-old girl of Finnish descent presents with oral thrush that is difficult to treat. Over the past year, she has had several episodes of tingling in her hands and feet. Laboratory tests reveal hypocalcemia and an inappropriately low parathyroid hormone level. What other condition is she at high risk of developing as a teenager?