[22q11.2 microdeletion syndrome: Analysis of the care pathway before the genetic diagnosis]

Utility of Measuring Fetal Cavum Septum Pellucidum (CSP) Width During Routine Obstetrical Ultrasound for Improving Diagnosis of 22q11.2 Deletion Syndrome: A Case-Control Study

Objective

To evaluate the utility of measuring fetal cavum septum pellucidum (CSP) width during routine, mid-pregnancy ultrasound for improving diagnosis of 22q11.2 deletion syndrome amongst fetuses with and without conotruncal anomalies.

Patients and Methods

This was a retrospective case-control study (2005–2016). Fetuses and newborns with 22q11.2 deletion and/or conotruncal cardiac anomalies were identified using a regional, clinical database. A control group was assembled in a 2:1 ratio to create three groups for comparison: i) 22q11.2 deletion syndrome; ii) isolated conotruncal anomalies; and iii) controls. Eligibility was restricted to those with stored ultrasound images between 18–22 weeks’ gestation and a minimum biparietal diameter of 40 mm. Post-processing measurement of CSP width was performed in a standardized fashion by two blinded and independent study personnel. Descriptive and inferential statistics, regression modeling, and receiver operator curves (ROC) were used to compare outcomes between groups and evaluate sensitivity/specificity of CSP width as a marker of 22q11.2 deletion syndrome.

Results

Twenty-nine cases of 22q11.2 deletion and 64 cases of isolated conotruncal anomalies were matched to 186 healthy controls. Cases with 22q11.2 deletion syndrome had significantly larger CSP widths (5.36 mm; SD=1.2) compared to those with isolated conotruncal anomalies (3.75 mm; SD=1.11) and healthy controls (2.93 mm; SD=0.57; p<0.0001). There was no difference in CSP width amongst those with 22q11.2 deletion irrespective of the presence/absence of a conotruncal anomaly (p=0.362), or by type of conotruncal anomaly (p=0.211). Using a CSP width cutoff >4.3 mm, fetuses with 22q11.2 deletion can be accurately identified with good sensitivity (89.7%) and specificity (84%).

Conclusion

Fetuses with 22q11.2 deletion syndrome have dilated CSPs when compared to those with isolated conotruncal anomalies or controls. Because CSP dilation can be evaluated during routine mid-pregnancy ultrasound using standard images of the fetal head, measurement could easily be incorporated to enhance prenatal diagnosis of this phenotypically diverse condition.

Tremor and Parkinsonism in Chromosomopathies - A Systematic Review

The landscape of genetic forms of Parkinson's diseases (PD) has grown exponentially in recent years. Today, around 10% of PD cases are estimated to be of genetic etiology. However, the link between parkinsonism or tremor and chromosome disorders, both numerical and structural, has been neglected. We reviewed the occurrence and characteristics of parkinsonism and tremor syndromes in patients with chromosomic disorders. We searched PubMed for articles published until December 2018, using the non-MESH terms "Chromosomopathy," "karyotype," "chromosome," "aneuploidy," "deletion," "inversion," "insertion," "duplication," and "Parkinson," "Parkinsonism," "Tremor," and "Parkinsonian disorder." We restricted the search to human studies and selected articles for further analysis after abstract review. Tremor syndromes in which patients had another possible clinical reason for syndromes were excluded, as well as tremor syndromes associated with point mutations, imprinting syndromes, and patients presenting with other hyperkinetic disorders. Fifty-four articles were reviewed. Aneuploidies of sex chromosomes were the most common chromosomopathy. These patients more commonly exhibited postural and kinetic tremor, often meeting the description of essential tremor. In structural chromosomopathies, the most frequent association was PD and 22q11.2 deletion syndrome, but we found case reports and case series of several additional deletion and duplication syndromes. © 2021 International Parkinson and Movement Disorder Society.

CNVs in the 22q11.2 Chromosomal Region Should Be an Early Suspect in Infants with Congenital Cardiac Disease

BACKGROUND

Congenital heart disease (CHD) is the most common congenital malformation, it is frequently found as an isolated defect, and the etiology is not completely understood. Although most of the cases have multifactorial causes, they can also be secondary to chromosomal abnormalities, monogenic diseases, microduplications or microdeletions, among others. Copy number variations (CNVs) at 22q11.2 are associated with a variety of symptoms including CHD, thymic aplasia, and developmental and behavioral manifestations. We tested CNVs in the 22q11.2 chromosomal region by MLPA in a cohort of Colombian patients with isolated CHD to establish the frequency of these CNVs in the cohort.

METHODS

CNVs analysis of 22q11.2 by MLPA were performed in 32 patients with apparently isolate CHD during the neonatal period. Participants were enrolled from different hospitals in Bogotá, and they underwent a clinical assessment by a cardiologist and a clinical geneticist.

RESULTS

CNVs in the 22q11.2 chromosomal region were found in 7 patients (21.9%). The typical deletion was found in 6 patients (18.75%) and atypical 1.5 Mb duplication was found in 1 patient (3.1%).

CONCLUSIONS

CNVs in 22q11.2 is a common finding in patients presenting with isolated congenital cardiac disease, therefore these patients should be tested early despite the absence of other clinical manifestations. MLPA is a very useful molecular method and provides an accurate diagnosis.