22q11.2 Microduplication: An Enigmatic Genetic Disorder

Kylat, Ranjit I

doi:10.1055/s-0038-1655754

Cited by 4 publications

(5 citation statements)

References 24 publications

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“…22q11.2DupS is associated with highly variable clinical features, ranging from completely normal to slightly abnormal features with milder learning disabilities to severe intellectual disability [5,18]. Therefore, very few cases have been reported, and the absence of obvious clinical features makes diagnosis difficult [19]. Similarly, no ultrasound abnormalities were observed in the two cases of 22q11.2DupS in this study.…”

Section: Discussionmentioning

confidence: 48%

“…These results and those from the literature [8] suggest that 22q11.2DupS does not have an accurate clinical phenotype. The extent of correlation between the phenotype and CNV depends on many factors, including previous evidence of pathogenic CNVs in the same region, type of CNV (duplication or deletion), gene content, inheritance pattern, and frequency in healthy populations [9,19]. Our case reports have provided useful information for subsequent research and genetic counseling.…”

Section: Discussionmentioning

confidence: 88%

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Prenatal diagnosis of rearrangements in the fetal 22q11.2 region

Jin

Yang

et al. 2020

Mol Cytogenet

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Background: 22q11.2 deletion syndrome (22q11.2DS) and 22q11.2 duplication syndrome (22q11.2DupS) are the most common copy number variations in humans. The clinical phenotypes of these two syndromes are variable, and there are no large sample data on the prenatal detection rate for these two syndromes in the Chinese population. Results: We recruited 411 pregnant women who showed either abnormal prenatal ultrasound findings or positive prenatal BoBs™ results or who had given birth to a child with chromosomal abnormalities. SNP-array analysis and interphase FISH analysis identified five fetuses with 22q11.2 copy number variants (CNVs), three of which were 22q11.2 deletion syndrome (22q11.2DS) (3/411) and two of which were 22q11.2 duplication syndrome (22q11.2DupS). In all 5 cases of diagnosed 22q11.2 abnormalities, inheritance could not be identified because the parents did not undergo further testing. Conclusion: Our case reports provide a detection rate of 22q11.2 CNVs for fetuses with prenatal diagnostic indications, and early diagnosis of these two syndromes was essential for prenatal intervention in these cases. SNP-array technology is an effective tool in the prenatal diagnosis of 22q11.2 CNVs. The prenatal diagnosis of these two syndromes is helpful for early intervention, which is of great clinical significance.

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Section: Discussionmentioning

confidence: 48%

Section: Discussionmentioning

confidence: 88%

Prenatal diagnosis of rearrangements in the fetal 22q11.2 region

Jin

Yang

et al. 2020

Mol Cytogenet

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“…This shows that population prevalence of both heterozygous recessive or dominant TLK2 gene mutations may be higher than currently recognized. A similar phenomenon can be seen in other known inherited heterozygous gene variants, where heterozygous parents of a proband are either clinically unaffected or have very mild disease, such as ASXL3 (Schirwani et al, 2021) and in several copy number variants such as 22q11.2 microdeletion syndrome (Kylat, 2018).…”

Section: Patientmentioning

confidence: 62%

Report of two children with global developmental delay in association with de novo TLK2 variant and literature review

Woods

Spiller

Balasubramanian

2021

American J of Med Genetics Pt A

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We describe clinical details, including novel findings, of two further children with the newly defined TLK2-related disorder. One patient was recruited to the Deciphering Developmental Delay (DDD) Study to identify underlying etiology of global developmental delay. The other was detected on whole-exome sequencing as part of second line investigations following normal microarray. Both patients were found to have de novo heterozygous pathogenic TLK2 variants. A novel c.6del p.(Glu3Lysfs*) loss-offunction frameshift variant was found in Patient 1. A c.1121+1G>A splice-donor variant was detected in Patient 2. TLK2-related neurodevelopmental disorder is a specific syndrome that has been recently described. Global developmental delay, behavioral problems, gastrointestinal disorders, and typical facial dysmorphism are common features. Neuropsychiatric disorders, ophthalmic, musculoskeletal and cranial abnormalities, as well as short stature, have also all been described. The novel findings we describe include sleep disturbance, nondifferentiation of lateral semicircular canals (where asymmetric semi-circular canals were a feature in the previous cohort), vesico-ureteric reflux, and bilateral periauricular skin tags. Here, we report a novel TLK2 variant and previously undescribed features of TLK2-related disorder, to expand the clinical phenotype and provide further genotype-phenotype correlation.

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“…The prevalence of 22q11.2 microduplication is low. This could be because of underdiagnosis due to milder phenotypic presentation and at the same time, microduplications are not easily detectable by karyotyping [3].…”

Section: Discussionmentioning

confidence: 99%

Phenotypic Overlap of 22q11.2 Microduplication and Noonan Syndrome in a Fetus with Increased NT, Facial Dysmorphism, and Narrow Pulmonary Trunk

Nerakh

Shah

Seshan

et al. 2022

Journal of Fetal Medicine

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22q11.2 deletion syndrome is a common microdeletion syndrome with a prevalence of 1 in 2000-6000 live births. Clinical features include conotruncal congenital heart defect (CHD), characteristic facial features, neurodevelopmental delay, and immunological abnormalities. Microduplications of 22q11.2 are rare compared to deletions due to ill-defined variable phenotype. A few cases of 22q duplication have been identified in the prenatal period in fetuses with increased nuchal translucency (NT), cardiac anomalies, cleft palate and micrognathia. We report a case of a fetus with increased NT in ultrasound and facial dysmorphism, narrow pulmonary trunk on autopsy evaluation, diagnosed to have microduplication of 22q11.2.

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22q11.2 Microduplication: An Enigmatic Genetic Disorder

Cited by 4 publications

References 24 publications

Prenatal diagnosis of rearrangements in the fetal 22q11.2 region

Prenatal diagnosis of rearrangements in the fetal 22q11.2 region

Report of two children with global developmental delay in association with de novo TLK2 variant and literature review

Phenotypic Overlap of 22q11.2 Microduplication and Noonan Syndrome in a Fetus with Increased NT, Facial Dysmorphism, and Narrow Pulmonary Trunk

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