WBR0609

Author	[[PageAuthor::Ayokunle Olubaniyi, M.B,B.S [1]]]
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 is referred to the pediatric cardiology clinic on account of heart murmurs and occasional constipation. On examination, the child exhibits an unusual cheerful demeanor, a low nasal bridge with a bulge forehead, and a mild speech difficulty. Cardiac auscultation reveals a grade 3/6, mid-ejection systolic murmur radiating to the right carotid artery. Echocardiography reveals supravalvular aortic stenosis. You suspect a rare neurodevelopmental disorder and ordered a fluorescent in situ hybridization (FISH) which confirms a deletion at chromosome 7q11.23. Which of the following electrolyte abnormalities is most likely expected in this patient?]]
Answer A	AnswerA::Hypocalcemia
Answer A Explanation	AnswerAExp::This is a feature seen in DiGeorge syndrome.
Answer B	AnswerB::Hypokalemia
Answer B Explanation	AnswerBExp::This may be seen 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::This is not a feature of Williams syndrome.
Answer D	AnswerD::Hypercalcemia
Answer D Explanation	AnswerDExp::This is a common feature of Williams syndrome.
Answer E	AnswerE::Hyperkalemia
Answer E Explanation	AnswerEExp::This is not a usual feature of Williams.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Williams syndrome (a.k.a. Williams–Beuren syndrome) is a rare neurodevelopmental disorder first identified in 1961 by New Zealander Dr. J. C. P. Williams. It is 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 supravalvular pulmonary stenosis, heart murmurs, renal artery stenosis leading to hypertension - Renal insufficiencies - Hypercalcemia, hypercalciuria, subclinical hypothyroidism The patient in this question has a combination of elfin facies, 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 extra calcium and vitamin D, as well as treating high levels of blood calcium. Other treatments are based on patients’ symptoms. Educational Objective: Williams syndrome is a rare neurodevelopmental disorder caused by a deletion at chromosome 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 Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Williams syndrome, WBRKeyword::Hypercalcemia
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::