Cryptic duplication and deletion of 9q34.3 --> qter in a family with a t(9;22)(q34.3;p11.2)

A Systematic Review of Reproductive Counseling in Cases of Parental Constitutional Reciprocal Translocation (9;22) Mimicking BCR-ABL1

We aim to determine the spectrum of cytogenetic abnormalities and outcomes in unbalanced offspring of asymptomatic constitutional balanced t(9;22) carriers through a systematic literature review. We also include a case of a constitutional balanced t(9;22) carrier from our institution. Among the 16 balanced t(9;22) carriers in our review, 13 were maternal and 3 were paternal. Of the 15 unbalanced translocation cases identified, 13 were live births, one was a missed abortion, and one resulted in pregnancy termination. The spectrum of established syndromes reported among the live births was the following: trisomy 9p syndrome (6/13), dual trisomy 9p and DiGeorge syndrome (3/13), dual 9q subtelomere deletion syndrome and DiGeorge syndrome (1/13), 9q subtelomere deletion syndrome (1/13), and DiGeorge syndrome (1/13). One unbalanced case did not have a reported syndrome. The phenotype of the unbalanced cases included cardiac abnormalities (5/13), neurological findings (7/13), intellectual disability (6/10), urogenital anomalies (3/13), respiratory or immune dysfunction (3/13), and facial or skeletal dysmorphias (13/13). Any constitutional balanced reciprocal t(9;22) carrier should be counseled regarding the increased risk of having a child with an unbalanced translocation, the spectrum of possible cytogenetic abnormalities, and predicted clinical phenotype for the unbalanced derivative.

Prenatal diagnosis of laryngo-tracheo-esophageal anomalies in fetuses with congenital diaphragmatic hernia by ultrasound evaluation of the vocal cords and fetal laryngoesophagoscopy

BACKGROUND

To evaluate the incidence of laryngeal ultrasound (US) abnormalities in fetuses with congenital diaphragmatic hernia (CDH) and to assess the utility of fetal laryngoesophagoscopy for prenatal diagnosis of laryngo-tracheo-esophageal anomalies.

STUDY DESIGN

A cohort of CDH fetuses with laryngeal ultrasound abnormalities were selected for diagnostic fetal laringoesophagoscopy in a single fetal surgery center at Queretaro, Mexico.

RESULTS

During the study period, 210 CDH fetuses were evaluated. US examination of the vocal cords was successfully performed in all fetuses, and abnormal ultrasound findings were observed in four cases (1.9%). Fetal laringoesophagoscopy was successfully performed in all four cases at a median gestational age of 29.5 (range, 28.1-30.6) weeks. During fetal intervention, a laryngo-tracheo-esophageal cleft (TEC) extending from the larynx to the carina (type IV) was endoscopically visualized in three cases, and laryngeal atresia coexisting with TEC was confirmed in the remaining case. Fetal karyotype was normal in all cases, but abnormal chromosomal microarray analysis was reported in two cases (50%). All cases were delivered liveborn with severe respiratory failure presenting cardiac arrest and immediate neonatal death.

CONCLUSIONS

Laryngeal anomalies in CDH fetuses can be presumed by ultrasound evaluation of the vocal cords and confirmed by fetal laryngoesophagoscopy during pregnancy.

9q34.3 microduplications lead to neurodevelopmental disorders through EHMT1 overexpression

Both copy number losses and gains occur within subtelomeric 9q34 region without common breakpoints. The microdeletions cause Kleefstra syndrome (KS), whose responsible gene is EHMT1. A 9q34 duplication syndrome (9q34 DS) had been reported in literature, but it has never been characterized by a detailed molecular analysis of the gene content and endpoints. To the best of our knowledge, we report on the first patient carrying the smallest 9q34.3 duplication containing EHMT1 as the only relevant gene. We compared him with 21 reported patients described here as carrying 9q34.3 duplications encompassing the entire gene and extending within ~ 3 Mb. By surveying the available clinical and molecular cytogenetic data, we were able to discover that similar neurodevelopmental disorders (NDDs) were shared by patient carriers of even very differently sized duplications. Moreover, some facial features of the 9q34 DS were more represented than those of KS. However, an accurate in silico analysis of the genes mapped in all the duplications allowed us to support EHMT1 as being sufficient to cause a NDD phenotype. Wider patient cohorts are needed to ascertain whether the rearrangements have full causative role or simply confer the susceptibility to NDDs and possibly to identify the cognitive and behavioral profile associated with the increased dosage of EHMT1.

The chromosome 9q subtelomere deletion syndrome

The chromosome 9q subtelomere deletion syndrome (9qSTDS) is among the first and most common clinically recognizable syndromes to arise from widespread testing by fluorescent in situ hybridization (FISH) of subtelomere deletions. There are about 50 reported cases worldwide. Affected individuals invariably have severe hypotonia with speech and gross motor delay. The facial gestalt is distinct and features absolute or relative micro- or brachycephaly, hypertelorism, synophrys, and/or arched eyebrows, mid-face hypoplasia, a short nose with upturned nares, a protruding tongue with everted lower lip and down-turned corners of the mouth. Approximately half of affected individuals have congenital heart defects (primarily ASD or VSD). A significant minority have epilepsy and/or behavioral and sleep disturbances. A variety of other major and minor eye, ear, genital, and limb anomalies have been reported. Most patients have sub-microscopic deletions of the subtelomere region of chromosome 9q34.3 that range from <400 kb to >3 Mb. The 9qSTDS is caused by haplo-insufficiency of EHMT1, a gene whose protein product (Eu-HMTase1) is a histone H3 Lys 9 (H3-K9) methyltransferase. This was established by identification of three patients with features of the syndrome and either mutations or a balanced translocation in EHMT1. H3-K9 histone methylation is restricted to the euchromatin of mammals and functions to silence individual genes. Deletion size does not correlate with the severity of the 9qSTDS since patients with mutations in EHMT1 are as severely affected as those with submicroscopic deletions. Patients clinically suspected of having the 9qSTDS but with normal subtelomere deletion testing by FISH or MLPA should be considered for detailed 9q MLPA analysis and/or sequencing of EHMT1. EHMT1 is another example in the growing list of genes responsible for brain development that appear to play a role in chromatin remodeling. Published 2007 Wiley-Liss, Inc.