Journal of Clinical & Medical Genomics

Hypomelanosis of Ito and De novo Interstitial 15q11.2q13.3 Triplication in Bulgarian Family

Abstract

Mladenova M, Koleva M, Rodopska E, Alexandrova I, Bojinova V, Plaseska-Karanfilska D, Bozinovski G, Todorova A and Mitev V

Here we report a case of Hypomelanosis of Ito (HI) and de novo interstitial 15q11.2q13.3 triplication. The HI is typically associated with various chromosomal anomalies, that is why a karyotyping was selected as a first choice in genetic approach. The obtained result showed a pathological karyotype: additional material on the long arm of chromosome 15,(15)(q11q13) bands. To confirm this extra material on the long arm of chromosome 15, our subsequent step was Multiplex Ligation-dependent Probe Amplification analysis (MLPA), which detected abnormal copy numbers, corresponding to duplication, along the targeted region 15q11.2 (genes SNRPN and UBE3A). In order to further clarify the duplication boundaries the aCGH was performed, which revealed arr[GRCh37] 15q1 1.2q13.3(22,558,697-30,366,124)x4, 15q13.2q13.3(30,652,489-32,462,701)x3. As a final step we conducted segregation analysis within the family by QF-PCR of polymorphic loci to identify the origin of the chromosomal rearrangement, which turned out to be maternally inherited. Based on the results from aCGH, in our opinion the reported here chromosomal rearrangement is an interstitial triplication of chromosome 15, resulting in very rare case of tetrasomy within the targeted region of chromosome 15q. Review of the literature showed that, here we report a first genetically proven case of Hypomelanosis of Ito caused by a de novo interstitial 15q11.2q13.3 triplication.