The first patient with tandem duplication of 6q14q16: Molecular and phenotypic characterization.

Duplications of the long arm of chromosome 6 have been previously reported in a limited number of patients; however, most reported duplications encompass regions of chromosome 6 distal to band q21. Duplications restricted to the proximal portion of 6q are rare. We report an 8-year-old male with a 16.4 megabase (Mb) tandem duplication of chromosome 6q14.1q16.1 (chr6:78950191-95395865; hg19) who exhibited dysmorphic facial features, seizures, global developmental delay, intellectual disability, autism spectrum disorder, sensorineural hearing loss, and immune deficiency. This patient refines and potentially expands the current, poorly-characterized phenotype associated with duplication of this proximal 6q region. We recommend a low threshold for a hearing evaluation beyond newborn screening and for pursuing an immune work-up in patients with similar 6q duplications. © 2016 Wiley Periodicals, Inc.

Characterization of six novel patients with MECP2 duplications due to unbalanced rearrangements of the X chromosome.

Males with duplication of the Xq28 region, including methyl CpG-binding protein 2 (MECP2), exhibit a characteristic phenotype, including developmental delay, intellectual disability, limited or absent speech, limited or absent ambulation, and recurrent respiratory infections. We report six males with MECP2 duplications identified using array comparative genomic hybridization. The minimal sizes of these duplications range from ∼0.08 to 14.13 Mb, which, to the best of our knowledge, are respectively the smallest and largest minimal size duplications molecularly characterized to date. Adjunct metaphase fluorescence in situ hybridization analysis further classified these duplications as tandem or as products of complex chromosomal rearrangements. Specifically, one complex rearrangement was described as a der(12)t(X;12)(q28;q24.33), which is the first report of a translocation involving MECP2 on Xq and chromosome 12. The other complex rearrangement was described as a rec(X)dup(Xq)inv(X)(p22.32q28)mat. Synthesis of the dysmorphic features identified in individuals with rec(X) chromosomes, including deletions in the pseudoautosomal region 1 (PAR1) at Xp22.33/Yp11.3 and duplications of the distal Xq region including MECP2, revealed a high prevalence of undescended testes (7/8) and micropenis (3/8) in this cohort. Given that micropenis is rare in the general population, but present in 38% of individuals in this cohort, a dosage anomaly at one or both loci may be a significant risk factor for this condition. Therefore, we recommend microarray testing for patients with unexplained micropenis, particularly when accompanied by other phenotypic anomalies.