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17p11.2p12 triplication and del(17)q11.2q12 in a severely affected child with dup(17)p11.2p12 syndrome
Author(s) -
Girirajan S,
Williams SR,
Garbern JY,
Nowak N,
Hatchwell E,
Elsea SH
Publication year - 2007
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.2007.00831.x
Subject(s) - gene duplication , biology , dup , genetics , comparative genomic hybridization , chromosome , gene dosage , fluorescence in situ hybridization , breakpoint , gene , gene expression
Multiple congenital anomalies/mental retardation syndromes due to genomic rearrangements involving chromosome 17p11.2 include deletion resulting in Smith–Magenis syndrome and a reciprocal duplication of the same region resulting in the 17p11.2 duplication syndrome. We present the clinical and molecular analysis of an 8‐year‐old male with a dup(17p11.2p12) who was evaluated for unusual severity of the phenotype. Fluorescent in situ hybridization (FISH) analysis not only confirmed the 17p duplication but also identified an ∼25% mosaicism for tetrasomy 17p11.2p12. Whole‐genome array comparative genomic hybridization (aCGH) was performed to identify other genomic rearrangements possibly contributing to the severe phenotype and the unusual features in the patient. The 17p duplication was determined by FISH and aCGH to encompass ∼7.5 Mb, from COX10 to KCNJ12 . An ∼830 Kb deletion of 17q11.2q12, including exon 1 of an amiloride‐sensitive cation channel neuronal gene, ACCN1 , was also identified by aCGH; breakpoints of the deletion were confirmed by FISH. Sequencing the non‐deleted allele of ACCN1 did not show any mutations. Western analysis of human tissue‐specific proteins revealed that ACCN1 is expressed not only in the brain as previously reported but also in all tissues examined, including heart, liver, kidneys, and spleen. The large‐sized 17p11.2p12 duplication, partial triplication of the same region, and the 17q11.2q12 deletion create a complex chromosome 17 rearrangement that has not been previously identified. This is the first case of triplication reported for this chromosome. Our study emphasizes the utility of whole‐genome analysis for known cases with deletion/duplication syndromes with unusual or severe phenotypes.