Complex distal 10q rearrangement in a girl with mild intellectual disability: follow up of the patient and review of the literature of non-acrocentric satellited chromosomes

Terminal 10q26.12 deletion is associated with neonatal asymmetric crying facies syndrome: a case report and literature review

Background

The terminal 10q26 deletion syndrome is a clinically heterogeneous disorder without identified genotype–phenotype correlations. We reported a case of congenital asymmetric crying facies (ACF) syndrome with 10q26.12qter deletion and discussed their genotype–phenotype correlations and the potentially contributing genes involving the etiology of ACF.

Methods and results

We reported a case of neonatal 10q26.12qter deletion and summarized the genotype–phenotype correlations and contributing genes of 10q26.12qter deletion from DECIPHER database and published studies. Meanwhile, we analyzed the potential pathogenic genes contributing to 10q26 deletion syndrome. The female preterm infant harboring 10q26.12qter deletion showed symptoms of abnormal craniofacial appearance with rare congenital asymmetric crying facies, developmental retardation, congenital heart disease, and pulmonary artery hypertension. The deleted region was 13.28 Mb in size as detected by G-banding and array comparative genome hybridization, containing 62 Online Mendelian Inheritance in Man (OMIM) catalog genes. We summarized data from 17 other patients with 10q26.12qter deletion, 11 from the DECIPHER database and 6 from published studies. Patients with monoallelic WDR11 and FGFR2 deletions located in 10q26.12q26.2 were predisposed to craniofacial dysmorphisms, growth retardation, intellectual disability and cardiac diseases.

Conclusion

ACF is a facial dysmorphism frequently accompanied by other systemic deformities. It is a genetic abnormality that may associate with terminal 10q26.12 deletion. Early cardiac, audiologic, cranial examinations and genetic detection are needed to guide early diagnosis and treatment strategy.

Instability of Short Arm of Acrocentric Chromosomes: Lesson from Non-Acrocentric Satellited Chromosomes. Report of 24 Unrelated Cases

Satellited non-acrocentric autosomal chromosomes (ps–qs-chromosomes) are the result of an interchange between sub- or telomeric regions of autosomes and the p arm of acrocentrics. The sequence homology at the rearrangement breakpoints appears to be, among others, the most frequent mechanism generating these variant chromosomes. The unbalanced carriers of this type of translocation may or may not display phenotypic abnormalities. With the aim to understand the causative mechanism, we revised all the ps–qs-chromosomes identified in five medical genetics laboratories, which used the same procedures for karyotype analysis, reporting 24 unrelated cases involving eight chromosomes. In conclusion, we observed three different scenarios: true translocation, benign variant and complex rearrangement. The detection of translocation partners is essential to evaluate possible euchromatic unbalances and to infer their effect on phenotype. Moreover, we emphasize the importance to perform both, molecular and conventional cytogenetics methods, to better understand the behavior of our genome.

A paternal t(6;22)(q25.3;p12) leading to a deleted and satellited der(6) in a short-lived infant

Background

Non‐acrocentric satellited chromosomes mostly result from familial balanced insertions or translocations with p12 or p13 of any acrocentric. Although all non‐acrocentrics have been involved, only 12 instances of chromosome 6 involvement are known.

Case presentation

A female infant exhibited clinical features typical of 6qter deletions and also generalized hypertrichosis and synophrys, traits seldom reported in patients with similar imbalances or haploinsufficiency of ARID1B located in 6q25.3. She had a paternal derivative satellited 6q of a t(6;22)(q25.3;p12)pat entailing a 6q terminal deletion, karyotype 46,XX,der(6)t(6;22)(q25.3;p12)pat [16].ish del 6q subtel–.

Conclusion

Male and female carriers of reciprocal translocations or insertions between chromosome 6 and the short arm of any acrocentric have few unbalanced offspring mostly by adjacent‐1 segregation. In addition, spontaneous abortions or male infertility was present in 7/13 instances of satellited chromosome 6.

Familiar unbalanced complex rearrangements involving 13 p-arm: description of two cases

Background

Copy number variations (CNVs) are largely known today, but their position is rarely established by fluorescence in situ hybridization (FISH) or karyotype analysis.

Case presentation

We described two families with copy number gain in which FISH analysis with the specific subtelomeric probe of chromosome 4q and 7q evidenced a third signal at band 13p11.2. Genomic study by array comparative genomic hybridization defined the triple dose segment. In the first case, the duplicate tract is free of known genes, in the second one it contained three expressed genes.

Conclusions

The CNV localization on the short arm of an acrocentric chromosome could explain the lack of phenotypic effect, being known the regulatory role of heterochromatin in the position-effect silencing. Furthermore, we would like to underline the importance of using complementary techniques such as FISH and array-CGH to obtain a better definition of genomic rearrangements.

Trisomy Xp and partial tetrasomy Xq resulting from gain of a rearranged X chromosome in a female fetus: pathogenic or not?

Cytogenetic analysis of chorionic villous sampling revealed a mosaic karyotype with gain of a rearranged X chromosome. Microarray and additional studies indicated that the rearranged X carried an inverted duplication, a deletion and a satellited Xqter. Gain of this rearranged X was confirmed by follow-up amniocentesis and postnatal cord blood sample. A full-term infant girl was delivered and showed normal physical findings at both birth and 21-month follow-up examinations. Late replication studies demonstrated that the rearranged X was inactivated in all abnormal cells analyzed. Skewed X-inactivation may suppress the potentially deleterious effects of genomic imbalance; however, gain of X chromosomes, particularly rearranged X chromosomes, often presents challenges for prenatal genetic counseling. The gradation of clinical phenotype severity generally correlates with the number of additional X chromosomes. However, the X chromosome regions responsible for the abnormal phenotypes are poorly understood. This case will further elucidate the phenotypic effects of X inactivation and X chromosome abnormalities.

An interstitial deletion at 10q26.2q26.3

We present a case of an interstitial subtelomeric 10q26 deletion in a male child with moderate developmental delay and minor dysmorphic features. Using array comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH), we have detected an interstitial deletion at 10q26.2q26.3 encompassing a 5.8 Mb region and spanning 24 genes. Interestingly, losses of this chromosome 10 region have not been previously associated with a phenotype outcome. According to an in silico evaluation, we have suggested that PPP2R2D and BNIP3 losses are likely a cause of developmental delay in the index patient. Our data allow to speculating that haploinsufficiency of these two genes in 10q26.3, which is usually ignored in the context of chromosome 10q deletions, has a phenotypic effect.

Distal 10q monosomy: new evidence for a neurobehavioral condition?

Pure distal monosomy of the long arm of chromosome 10 is a rare cytogenetic abnormality. The location and size of the deletions described in this region are variable. Nevertheless, the patients share characteristic facial appearance, variable cognitive impairment and neurobehavioral manifestations. A Minimal Critical Region corresponding to a 600 kb Smallest Region of deletion Overlap (SRO) has been proposed. In this report, we describe four patients with a distal 10q26 deletion, who displayed attention-deficit/hyperactivity disorders (ADHD). One of them had a marked behavioral profile and relatively preserved cognitive functions. Interestingly, the SRO was not included in the deleted segment of this patient suggesting that this deletion could contain candidate genes involved in the control of neurobehavioral functions. One of these candidates was the CALY gene, known for its association with ADHD patients and whose expression level was shown to be correlated with neurobehavioral disturbances in varying animal models. This report emphasizes the importance of the behavioral problems as a cardinal feature of the 10q microdeletion syndrome. Haploinsufficiency of CALY could play a crucial role in the development of the behavioral troubles within these patients.

Inverted Duplication and Deletion of 10q25q26 in a Patient without Any Obvious Skeletal Anomalies

We report on a girl with inverted duplication and deletion of 10q25q26 revealed by array-CGH and FISH analysis. Array-CGH analysis demonstrated a ∼13.1-Mb duplication encompassing 10q25.3q26.2 and a ∼5-Mb deletion at 10q26.2q26.3. No single-copy region was detected between the deleted and duplicated segments. FISH analysis found the arrangement duplicated in an inverted position. FISH analysis using the same probes did not show any abnormality in both parents, which indicates a de novo occurrence. The frequently reported features of distal 10q duplication include developmental delay, blepharophimosis, hypotonia, skeletal anomalies and some facial dysmorphisms. The girl presented with many features of distal 10q duplication with the exception of skeletal anomalies. To our knowledge, this is the fourth patient reported in the literature with inv dup del 10q. 10q duplication seems to account for most of the phenotypes for our patient. Although no obvious skeletal feature was found in our patient at present, follow-up assessment of skeletal development should be planned with the increase of age.