1.15 Mb microdeletion in chromosome band 20p13 associated with moderate developmental delay-additional case and data's review

Subtelomeric microdeletion in chromosome 20p13 associated with short stature

Key Clinical Message

Among the total 10 reported cases with 20p13 microdeletion, including our patient, it is notable that 50% of patients presented a height below the 3rd percentile. We suggest that short stature is among the most common manifestations in patients with 20p13 subtelomeric microdeletion.

Abstract

Chromosome 20p13 microdeletion occurs rarely, with only 10 reported cases. We report a 16-year-old male with a 1.59 Mb terminal deletion in chromosome 20p13, who presented with proportionate short stature, mild language delay, mild learning disability, and delayed puberty. The clinical phenotype associated with this deletion can exhibit clinical variability. Our patient deviates from the typical developmental and intellectual phenotype seen in the 20p13 deletion, instead displaying mild speech delay, short stature, and delayed puberty. The CSNK2A1 deletion, leading to haploinsufficiency, might be the potential mechanism. And the prominence of his proportionate short stature provides a unique perspective to review the existing literature.

Prenatal diagnosis of 20p13 microdeletion syndrome

OBJECTIVE

The objective of this study was to report the first case of prenatal diagnosis of the fetal 20p13 microdeletion syndrome in the literature.

CASE REPORT

The mother was 31 years old and had a first trimester serum screening that indicated the fetus was at low risk. The prenatal ultrasound at 23 weeks of gestation showed mild ventriculomegaly (10.2 mm) and absent septum pellucidum. She underwent amniocentesis because of the abnormal imaging results. Karyotype analysis revealed normal results. Chromosome microarray analysis (CMA) was then performed to provide genetic analysis of the fetus and parents. CMA detected 317.902 kb deletion of 20p13 in fetus. Finally, pregnancy was terminated at 32 weeks of gestation.

CONCLUSION

This study is the first to report the prenatal diagnosis of a 20p13 microdeletion syndrome. Our results further confirmed that genes in this region, including SOX12, NRSN2 are essential for normal fetal growth and TBC1D20 for normal brain development.

Phenotypic features of a microdeletion in chromosome band 20p13: A case report and review of the literature

Background

20p13 microdeletion syndrome has been reported to be associated with developmental delays, intellectual disability, epilepsy, and unspecific dysmorphic characteristics. However, only a few cases of 20p13 microdeletion have been described, and therefore its typical features and precise pathogenesis remain elusive.

Methods and Results

In this article, we report the case of a 9‐month‐old infant who presented with a large fontanelle, facial dysmorphism, and failure to thrive. Array‐comparative genomic hybridization (aCGH) analysis confirmed a 2.01‐Mb microdeletion in chromosome band 20p13 that involved SOX12 and NRSN2, both of which are considered paramount causative genes in patients with 20p13 microdeletion. To elucidate the typical features of 20p13 microdeletion, we further reviewed these previously reported cases and found that motor delay (90%) was the most common manifestation, followed by language delay (60%), abnormal digits (60%), mental retardation (50%), large fontanelle (50%), electroencephalography abnormalities (50%), and seizure (40%).

Conclusion

This report highlights the potential of aCGH as a practical and powerful tool with which to detect submicroscopic chromosomal abnormalities in individuals presenting with a wide spectrum of phenotypes, ranging from facial dysmorphism to failure to thrive. Additionally, the literature review casts new light on the clinical features of 20p13 microdeletion.

The frequency of CNVs in a cohort population of consecutive fetuses with congenital anomalies after the termination of pregnancy

BACKGROUND

The implementation of molecular karyotyping has resulted in an improved diagnostic yield in the genetic diagnostics of congenital anomalies, detected prenatally or after the termination of pregnancy. However, the systematic epidemiologic ascertainment of copy number variations in the etiology of congenital anomalies has not yet been sufficiently explored.

METHODS

Consecutive fetuses, altogether 204, with major single or multiple congenital anomalies were ascertained by using the SLOCAT registry for the period from 2011 to 2015. After excluding aneuploidies by using conventional karyotyping or Quantitative Fluorescence-Polymerase Chain Reaction, array comparative genomic hybridization was performed for the detection of copy number variations.

RESULTS

We identified pathogenic or likely pathogenic copy number variations in 14 fetuses (6.8%); 2.9% in fetuses with isolated, and 3.9% in fetuses with multiple congenital anomalies. Additionally, aneuploidies and major structural chromosomal abnormalities were detected in 40.2%.

CONCLUSION

Our systematic approach of ascertaining congenital anomalies resulted in explaining the etiology of congenital anomalies in 47% of fetuses after the termination of pregnancy. By using array comparative genomic hybridization, we found that copy number variations represent an important part in the etiology of multiple, as well as isolated congenital anomalies, which indicates the importance of analyzing copy number variations in the diagnostic approach of fetuses with congenital anomalies after the termination of pregnancy.

Clinical and molecular cytogenetic analyses of four patients with imbalanced translocations

Background

Chromosomal abnormalities that result in genomic imbalances are main causes of congenital and developmental anomalies including intellectual disability and multiple congenital malformations. In this report we describe four patients from three families with imbalanced translocations. Only a small percentage of imbalanced translocation individuals can be born to live, most of them were aborted in embryonic period. It is of great significances to precisely analysis the chromosome variation to study the relationship between genotype and phenotype.

Results

Four patients showed common clinical manifestations including delayed growth, intellectual disability, language barrier and facial dysmorphisms. In addition to the above features, lower limbs dysplasia and both foot eversion were found in patient 1, brachydactylic hand, cerebellar ataxia and congenital heart defects were also found in patient 4. Conventional karyotype analysis revealed abnormal karyotypes 46, XX, der (6) t (6: 10) (p23; q24), 46, XX, der (20) t (3; 20) (p23; p13) and 46, XX, der (22) t (3; 22) (q27; q13.3) in the four patients, respectively. Array-CGH analyses confirmed 23.6 Mb duplication on 10q25.1-q26.3 and 0.9 Mb deletions on 6p25.3, 19.9 Mb duplication on 3p24.3-p26.3 and 0.25 Mb deletion on 20p13 and 12.5 Mb duplication on 3q27.2-q29 and 1.9 Mb deletions on 22q13.2-q13.33 in the four patients, respectively.

Conclusion

Parents with balanced translocation are passed the imbalanced chromosome to patient, and the partial monosomy and partial trisomy lead to multiple congenital malformations of four patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-016-0244-x) contains supplementary material, which is available to authorized users.