Interstitial 10p deletion derived from a maternal ins(16;10)(q22;p13p15.2): Report of the first familial case of 10p monosomy affecting to two familial members of different generations.

Monosomy 10p is a rare chromosomal disorder with a prevalence <1/1,000,000, in which a terminal or interstitial distal region of chromosome 10 is deleted resulting in a variable phenotype depending on the size of the deletion. Two main phenotypes have been defined depending on the location of the deletion: HDR syndrome (Hypoparathyroidism, sensorineural Deafness, and Renal disease), and DGS2 (DiGeorge syndrome type 2). The vast majority of cases reported so far have resulted from de novo events. Here, we present the first familial presentation of this contiguous gene deletion syndrome, affecting two family members in different generations: a child and his maternal uncle. In both cases, the deletion was due to a malsegregation of a maternal balanced rearrangement, ins(16;10)(q22;p13p15.2). The identification and characterization of this rearrangement was possible using a combination of different genetic analyses such as karyotype, MLPA, FISH, and array CGH. We underline the importance of the present results in terms of genetic and reproductive counseling for the carriers of the balanced rearrangement within the family, and demonstrate again the utility of expanding the genetic studies to the relatives of the affected patients.