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Deletion Syndromes Atf

The document discusses deletion syndromes, which are caused by partial deletions of chromosomes, often resulting from errors during meiosis. Key syndromes highlighted include Cri-du-chat, characterized by severe intellectual disability and distinct facial features, Williams syndrome, which involves a deletion on chromosome 7 leading to unique facial characteristics and friendly behavior, and Thymic aplasia (DiGeorge syndrome), associated with immune deficiency and congenital heart defects. Each syndrome presents specific clinical features and implications for affected individuals.

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16 views14 pages

Deletion Syndromes Atf

The document discusses deletion syndromes, which are caused by partial deletions of chromosomes, often resulting from errors during meiosis. Key syndromes highlighted include Cri-du-chat, characterized by severe intellectual disability and distinct facial features, Williams syndrome, which involves a deletion on chromosome 7 leading to unique facial characteristics and friendly behavior, and Thymic aplasia (DiGeorge syndrome), associated with immune deficiency and congenital heart defects. Each syndrome presents specific clinical features and implications for affected individuals.

Uploaded by

samsungs007plus2021
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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AfraTafreeh.

com

Deletion
Syndromes
Jason Ryan, MD, MPH
Deletion Syndromes
• Partial deletion of chromosome
• Long or short arm
• Portion of long/short arm

AfraTafreeh.com
AfraTafreeh.com

Deletion Syndromes
• Usually an error in crossover in meiosis
• Unbalanced exchange of genes
• One chromosome with duplication; other with deletion

Meiosis
Replication/Crossover

Interphase
Deletion Syndromes
• Most cases sporadic (congenital)
• Key syndromes:
• Cri-du-chat
• Williams
• Thymic aplasia AfraTafreeh.com
AfraTafreeh.com

Cri-du-chat Syndrome
• Deletion of part of short arm (p) of chromosome 5
• “5p- syndrome”

Wikipedia/Public Domain
Cri-du-chat Syndrome
• Severe intellectual disability
• Cognitive, speech, motor delays
• Infants cry like a cat
• Classically described as “mewing”: high-pitched cry
• Occurs soon after birthAfraTafreeh.com
then resolves
AfraTafreeh.com

Cri-du-chat Syndrome
• Microcephaly (small head)
• Characteristic facial features
• Widely set eyes (hypertelorism)
• Low-set ears
• Small jaw
• Rounded face

Paola Cerruti Mainardi.


Cri-du-chat Syndrome
• Congenital heart defects
• Ventricular septal defect (VSD)
• Patent ductus arteriosus (PDA)
• Tetralogy of Fallot (TOF)
• Others AfraTafreeh.com
AfraTafreeh.com

Williams Syndrome
Williams-Beuren syndrome

• Partial deletion on long arm of chromosome 7


• Deleted portion includes gene for elastin
• Elastic protein in connective tissue
• Results in elastin “haploinsufficency”

Wikipedia/Public Domain
Williams Syndrome
Williams-Beuren syndrome

• Classically an “elfin” facial appearance


• Small nose
• Small chin
• Wide mouth
• Long philtrum (upper lip length)
AfraTafreeh.com
AfraTafreeh.com

Williams Syndrome
Williams-Beuren syndrome

• Intellectual disability
• Delayed developmental milestones
• Well-developed verbal skills
• Extremely friendly with strangers
• Unafraid of strangers
• Great interest in talking with adults
Williams Syndrome
Vascular Manifestations

• Supravalvular aortic stenosis


• Constriction of ascending aorta above aortic valve
• High prevlence among children with WS
• Pulmonary artery stenosis
• Renal artery stenosis AfraTafreeh.com
AfraTafreeh.com

Williams Syndrome
Hypercalcemia

• Higher calcium than general pediatric population


• Evidence of ↑ vitamin D levels and ↑ vitamin D sensitivity
• Usually mild to moderate
• Does not usually cause symptoms
• May lead to constipation
Thymic Aplasia
DiGeorge Syndrome

• Many different names


• 22q11 deletion syndrome
• Velocardiofacial syndrome
• Shprintzen syndrome Wikipedia/Public Domain

• Conotruncal anomaly face syndrome


AfraTafreeh.com
• Partial deletion of long arm (q) chromosome 22
• Immune deficiency
• Hypocalcemia
• Congenital heart defects

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