The Principles of Clinical Cytogenetics - Extra Materials - Springer

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Table 2
Some Recurring Duplication/Triplication Syndromes
Duplication/ Duplicated/
triplication syndrome triplicated region Key clinical features
Duplication 3q ?3q26.3 A Cornelia de Lange-like phenotype that includes mental retardation postnatal growth
retardation, long philtrum, palate anomalies, anteverted nares, clinodactyly, talipes, renal
and cardiac abnormalities.
Beckwith–Wiedemann 11p15.5 Macrosomia, macroglossia, organomegaly, omphalocele, ear creases, hypoglycemia, tumor
(paternal) susceptibility; Beckwith-Wiedemann patients with cytogenetic duplications more likely to
have learning difficulties.
Pallister–Killian Mosaic tetrasomy 12p; usually Mental retardation, streaks of hyperpigmentation and hypopigmentation, sparse anterior scalp
secondary to an extra hair, sparse eyebrows and eyelashes, prominent forehead, protruding lower lip, coarsening of
metacentric isochromosome face with age.
Duplication of 15q11.2; typically of maternal Mild to severe intellectual impairment particularly with regard to language, autism spectrum
proximal 15q origin and complementary to disorders, decreased motor coordination, hypotonia, reduced deep tendon reflexes, joint laxity,
the Prader–Willi and Angelman mild or no dysmorphic features.
syndrome deletions
Pseudodicentric 15 Tetrasomy 15pter-15q13; the result Mental and growth retardation, autism, behavioral disturbance, seizures, low posterior hairline,
(inverted duplicated 15) of the presence of an extra epicanthal folds, low-set ears, strabismus; the smaller pseudodicentric 15 chromosomes might
pseudodicentric chromosome not cause phenotypic abnormalities.
Duplication of 17p11.2; duplication is Mild to borderline mental retardation, behavioral problems, short stature, normal facies, dental
proximal 17p complementary to the Smith– abnormalities including malocclusion and crowded teeth.
Magenis syndrome deletion.
Duplication of 22q11.2; duplication is Currently no clearly established phenotype recognized; some patients noted to have features that
proximal 22q complementary to the DiGeorge overlapwith DiGeorge syndrome, including mental retardation and developmental delay,
syndrome deletion abnormalities of the palate, conotruncal heart defects, absent thymus and corresponding T-cell
deficiency; phenotype variable and ranges from mild to severe.
Cat-eye Tetrasomy 22q11.2 (occasionally Usually mild mental retardation, coloboma of the iris, downslanting palpebral fissures,
trisomy); usually secondary to an preauricular tags and/or fistulas, anal atresia.
extra pseudodicentric or ring
chromosome
Structural Chromosome Rearrangements 179