First prenatal diagnosis of a ‘pure’ 9q34.3 deletion (Kleefstra syndrome): A case report and literature review

Association of prenatal thoracic ultrasound abnormalities with copy number variants at a single Chinese tertiary center

OBJECTIVE

To systematically evaluate the association of prenatal thoracic ultrasound abnormalities with copy number variants (CNVs).

METHODS

Chromosomal microarray (CMA) data and clinical characteristics from fetuses with thoracic ultrasound abnormalities were retrieved and analyzed.

RESULTS

Thoracic ultrasound findings were mainly isolated except for fetal pleural effusion (FPE) and pulmonary hypoplasia. The diagnostic yield of CMA for thoracic anomaly was 9.66%, and FPE (17/68, 25%), pulmonary hypoplasia (1/8, 12.5%), and congenital diaphragmatic hernia (CDH) (6/79, 7.59%) indicated relatively high pathogenic/likely pathogenic (P/LP) CNV findings. The detection rate for P/LP CNVs was obviously increased in non-isolated thoracic anomalies (27.91% vs. 1.96%, P < 0.0001), non-isolated FPE (37.78% vs. 0%, P = 0.0007) and non-isolated congenital pulmonary airway malformation (CPAM) (27.27% vs. 0%, P < 0.0001), and significantly different among thoracic anomalies. Additionally, the rate of termination of pregnancy in cases with non-isolated thoracic anomalies (58.49% vs. 12.34%, P < 0.0001) and P/LP CNVs (85.71% vs. 24.15%, P < 0.0001) was obviously increased.

CONCLUSION

The present study expanded phenotype spectrums for particular recurrent CNVs. FPE, CDH, and pulmonary hypoplasia indicated relatively high P/LP CNV findings among common thoracic ultrasound abnormalities, CPAM associated with other ultrasound abnormalities increased the incidence of diagnostic CNVs, while bronchopulmonary sequestration might not be associated with positive CNVs. The present data recommended CMA application for cases with prenatal thoracic ultrasound abnormalities, especially non-isolated FPE, non-isolated CPAM, CDH, and pulmonary hypoplasia.

MLPA analysis of 32 foetuses with a congenital heart defect and 1 foetus with renal defects - pilot study. The significant frequency rate of presented pathological CNV

AIMS

The aim of this retrospective study was to determine the detection rate of the pathogenic copy number variants (CNVs) in a cohort of 33 foetuses - 32 with CHD (congenital heart defects) and 1 with kidney defect, after exclusion of common aneuploidies (trisomy 13, 18, 21, and monosomy X) by karyotyping, Multiplex ligation - dependent probe amplification (MLPA) and chromosomal microarray analysis (CMA). We also assess the effectivity of MLPA as a method of the first tier for quick and inexpensive detection of mutations, causing congenital malformations in foetuses.

METHODS

MLPA with probe mixes P070, P036 - Telomere 3 and 5, P245 - microdeletions, P250 - DiGeorge syndrome, and P311 - CHD (Congenital heart defects) was performed in 33 samples of amniotic fluid and chorionic villi. CMA was performed in 10 relevant cases.

RESULTS

Pathogenic CNVs were found in 5 samples: microdeletions in region 22q11.2 (≈2 Mb) in two foetuses, one distal microdeletion of the 22q11.2 region containing genes LZTR1, CRKL, AIFM3 and SNAP29 (≈416 kb) in the foetus with bilateral renal agenesis, 8p23.1 (3.8 Mb) microdeletion syndrome and microdeletion in area 9q34.3 (1.7 Mb, Kleefstra syndrome). MLPA as an initial screening method revealed unambiguously pathogenic CNVs in 15.2 % of samples.

CONCLUSION

Our study suggests that MLPA and CMA are a reliable and high-resolution technology and should be used as the first-tier test for prenatal diagnosis of congenital heart disease. Determination of the cause of the abnormality is crucial for genetic counselling and further management of the pregnancy.

Prenatal diagnosis of Kleefstra syndrome

Objectives

To describe the prenatal diagnosis of Kleefstra syndrome (KS), a rare panethnic disorder characterized by mental and developmental delays, distinct facial features, congenital heart and urogenital defects, among others. KS is caused by haploinsusufficiency and loss of function of euchromatin histone methyltransferase 1 (EHMT1) due to deletions or mutations in the chromosomal region 9q34.3.

Case presentation

The prenatal diagnosis of KS in this case report includes the description of subtle fetal phenotypic abnormalities detected by the fetal ultrasound examination as well as the results of the amniotic fluid microarray analysis that confirmed a fetal denovo deletion in the chromosomal region 9q34.3. These results confirmed the prenatal diagnosis of KS.

Conclusions

This case is noteworthy because of the late development of very subtle ultrasound abnormalities that triggered prenatal diagnostic studies in amniotic fluid cells, including SNP microarray analysis, that defined the diagnosis of KS. It allowed us to obtain the necessary antepartum consultations with neonatology, other pediatric subspecialties and arrange for the patient’s appropriate place of delivery to optimize the fetal and neonatal outcome.

Convergent epigenetic regulation of glial plasticity in myelin repair and brain tumorigenesis: A focus on histone modifying enzymes

Brain regeneration and tumorigenesis are complex processes involving in changes in chromatin structure to regulate cellular states at the molecular and genomic level. The modulation of chromatin structure dynamics is critical for maintaining progenitor cell plasticity, growth and differentiation. Oligodendrocyte precursor cells (OPC) can be differentiated into mature oligodendrocytes, which produce myelin sheathes to permit saltatory nerve conduction. OPCs and their primitive progenitors such as pri-OPC or pre-OPC are highly adaptive and plastic during injury repair or brain tumor formation. Recent studies indicate that chromatin modifications and epigenetic homeostasis through histone modifying enzymes shape genomic regulatory landscape conducive to OPC fate specification, lineage differentiation, maintenance of myelin sheaths, as well as brain tumorigenesis. Thus, histone modifications can be convergent mechanisms in regulating OPC plasticity and malignant transformation. In this review, we will focus on the impact of histone modifying enzymes in modulating OPC plasticity during normal development, myelin regeneration and tumorigenesis.

Chromosomal microarray analysis in fetuses with an isolated congenital heart defect: A retrospective, nationwide, multicenter study in France

OBJECTIVES

Congenital heart defects (CHDs) may be isolated or associated with other malformations. The use of chromosome microarray (CMA) can increase the genetic diagnostic yield for CHDs by between 4% and 10%. The objective of this study was to evaluate the value of CMA after the prenatal diagnosis of an isolated CHD.

METHODS

In a retrospective, nationwide study performed in France, we collected data on all cases of isolated CHD that had been explored using CMAs in 2015.

RESULTS

A total of 239 fetuses were included and 33 copy number variations (CNVs) were reported; 19 were considered to be pathogenic, six were variants of unknown significance, and eight were benign variants. The anomaly detection rate was 10.4% overall but ranged from 0% to 16.7% as a function of the isolated CHD in question. The known CNVs were 22q11.21 deletions (n = 10), 22q11.21 duplications (n = 2), 8p23 deletions (n = 2), an Alagille syndrome (n = 1), and a Kleefstra syndrome (n = 1).

CONCLUSION

The additional diagnostic yield was clinically significant (3.1%), even when anomalies in the 22q11.21 region were not taken into account. Hence, patients with a suspected isolated CHD and a normal karyotype must be screened for chromosome anomalies other than 22q11.21 duplications and deletions.

Shone's complex in a patient with chromosome 9q34.3 deletion (Kleefstra syndrome)

Kleefstra syndrome (chromosome 9q34.3 deletion) is a rare genetic disorder with less than 110 patients reported till date. We report a 4-month-old Caucasian girl with Kleefstra syndrome and Shone's complex, an association which has not been previously reported. Surgical planning for patients with Kleefstra syndrome and complex CHD can pose challenges due to an uncertain natural history and a risk of post-operative pulmonary hypertension.