7q36 deletion and 9p22 duplication: effects of a double imbalance

Abstract

The etiology of mental retardation/developmental delay (MRDD) remains a challenge to geneticists and clinicians and can be correlated to environmental and genetic factors. Chromosomal aberrations are common causes of moderate to severe mental retardation and may represent 10% of these occurrences. Here we report the case of a boy with development delay, hypoplasia of corpus callosum, microcephaly, muscular hypotonia, and facial dysmorphisms. A deletion of 7q36.1 → 36.3 and duplication of 9p22.3 → 23 was detected as a result of an unbalanced translocation of paternal origin. Breakpoint delimitation was achieved with array comparative genomic hybridization assay. Additional multiplex ligation dependent probe amplification (MLPA) analyzes confirmed one copy loss of 7q36.3 region and one copy gain of 9p24.3 region. Patient resultant phenotype is consistent with the already described findings for both 7q deletion and 9p duplication syndromes.

Recombinant chromosome 4 in two fetuses - case report and literature review

“…Recombinant chromosome 4 syndrome (rec 4 syndrome) is a very rare genetic condition, primarily caused by a pericentric inversion of chromosome 4 in a parent [ 2 , 7 ]. A total of 18 rec (4) syndrome cases have been well-documented, showing different recombinant types and varying clinical presentations (17 in literature and 1 in DECIPHER database, Table 1 ) [ 5 , 7 – 20 ]. Generally, a pericentric inversion will give rise to four types of gametes during the meiosis, including two balanced and two unbalanced [ 18 , 21 ].…”

“…During meiosis in carriers, a chromosome containing a large inverted segment and its normal homolog are predicted to form a homosynaptic inversion loop, in order to obtain optimal pairing of the matching segment. Any odd number of crossovers within the inversion loop leads to the production of two alternate recombinant chromosomes: in one chromosome the distal part of the short arm is duplicated and the distal part of the long arm is deleted; the opposite occurs to be short arm deletion and long arm duplication [ 7 ]. In our study, although FISH was refused by the parents, the constitutional chromosomal abnormalities occurred in two fetuses are most probably consistent with recombinant (4) syndrome.…”

“…The clinical phenotype of rec (4) has been a subject of debate for years. Although previous studies have conducted the genotype-phenotype correlation of rec (4) syndrome, the results were contradictory, with some authors suggested that rec (4) syndrome appears to be an entity which can be suspected on the basis of specific clinical features [ 5 , 7 ], while others argued that rec (4) syndrome is not characterized by a recognizable phenotype [ 18 ]. The previous studies were unable to point out the genotype-phenotype relationship because they described the rec (4) syndrome as an entirety.…”

Detection of chromosomal translocations in formalin‐fixed paraffin‐embedded (FFPE) leukemic specimens by digital expression profiling

“…Further complicating MLPA is the need for standard curves to adjust for peak heights of different sizes. Similar to digital expression analysis, MLPA can detect chromosomal translocations from fresh peripheral blood samples. However, MLPA is more robust on fresh/frozen samples than FFPE samples .…”

Chromosomal imbalance letter: Phenotypic consequences of combined deletion 8pter and duplication 15qter

“…Inheritance of a balanced translocation from either or both parents is often responsible for structural chromosomal defects leading to segmental duplication or deletion of the chromosome pair in an affected individual [4]. The paradigm shift in diagnostics with the implementation of next generation in silico softwares and array based comparative genomic hybridization (aCGH) technology, chromosome breakpoint determination, analyses of critical regions involved in genetic disorders and copy number evaluation has helped to correlate chromosomal region alteration and the resulting phenotype [5,6]. …”