WBR0609

Author	[[PageAuthor::Ayokunle Olubaniyi, M.B,B.S [1] (Reviewed by Alison Leibowitz)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics
Sub Category	SubCategory::Cardiology, SubCategory::Endocrine, SubCategory::Neurology
Prompt	[[Prompt::A 4-year-old male presents with heart murmurs and occasional constipation. On examination, the child exhibits an unusually cheerful demeanor, a low nasal bridge with a bulge forehead and abnormally wide mouth with flattened, thick lips, and a mild speech delay. Cardiac auscultation reveals a grade 3/6, mid-systolic ejection murmur radiating to the right carotid artery. Echocardiography reveals supravalvular aortic stenosis. You suspect a rare neurodevelopmental disorder and order a fluorescent in situ hybridization (FISH) which confirms a deletion at chromosomal locus 7q11.23. Which of the following electrolyte abnormalities is most likely expected in this patient?]]
Answer A	AnswerA::Hypocalcemia
Answer A Explanation	AnswerAExp::Hypocalcemia is a feature seen commonly in DiGeorge syndrome.
Answer B	AnswerB::Hypokalemia
Answer B Explanation	AnswerBExp::Hypokalemia is a feature seen commonly in Williams syndrome especially when it is complicated by renal artery stenosis, but this is not frequently observed.
Answer C	AnswerC::Hypermagnesemia
Answer C Explanation	AnswerCExp::Hypermagnesemia is not a feature associated with Williams syndrome.
Answer D	AnswerD::Hypercalcemia
Answer D Explanation	AnswerDExp::Hypercalcemia is a common feature of Williams syndrome.
Answer E	AnswerE::Hyperkalemia
Answer E Explanation	AnswerEExp::Hyperkalemia is not a feature associated with Williams syndrome.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Williams syndrome Williams–Beuren syndrome is a rare neurodevelopmental disorder, caused by a deletion of about 26 genes from the long arm of chromosome 7, with an estimated prevalence of 1 in 7500 to 1 in 20,000 births. The major features of Williams syndrome include: Features include: Craniofacial dimorphism characterized by a distinctive, elfin facial appearance, along with a low nasal bridge, an unusually cheerful demeanor and ease with strangers. Oral abnormalities Mild to moderate mental retardation, cognitive disorder. Failure to thrive, short stature Cardiovascular features include supravalvular aortic stenosis or peripheral pulmonary stenosis, heart murmurs, renal artery stenosis leading to hypertension Renal insufficiencies Hypercalcemia, hypercalciuria, and subclinical hypothyroidism The patient has a combination of elfin facies, a systolic murmur suggesting aortic stenosis, and constipation, which is a symptom of high serum calcium. There is no cure for Williams syndrome. Management suggestions include avoidance of excess calcium and vitamin D, as well as treatment for high levels of blood calcium. Educational Objective: Williams syndrome is a rare neurodevelopmental disorder caused by a deletion at chromosomal locus 7q11.23. The main features include elfin facial appearance, mental retardation, supravalvular aortic stenosis, and hypercalcemia. Reference: http://www.wikidoc.org/index.php/Williams_syndrome References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Williams syndrome, WBRKeyword::Hypercalcemia
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::