4p16.1-p15.31 duplication and 4p terminal deletion in a 3-years old Chinese girl: Array-CGH, genotype-phenotype and neurological characterization

Genotype-phenotype correlation of deletions and duplications of 4p: case reports and literature review

Structural rearrangements of chromosome 4p gives rise to a group of rare genomic disorders that mainly result in two different clinical entities: Wolf-Hirschhorn syndrome (WHS) and partial 4p trisomy. The severity of the phenotype depends on the size of the deletion or locus duplication. Here, we present two unrelated individuals with a copy number variation of chromosome 4p. Inverted duplication deletions (inv dup-del) in 4p are particularly rare. Case 1 describes a 15-year-old girl with a 1.055 Mb deletion of terminal 4p, distal to the recognized critical region of WHS, and a large duplication of 9.6 Mb in size from 4p16.3 to p16.1. She had postnatal development delay, intellectual disability (especially pronounced in speech), seizure/electroencephalogram anomalies, and facial dysmorphic features. This unusual chromosomal imbalance resulted in the WHS phenotype rather than the 4p trisomy syndrome phenotype. Case 2 describes a 21-month-old boy with a 1.386 Mb terminal 4p deletion who presented with slight developmental delay, borderline intellectual disability, and seizures. Combined with previous reported cases of 4 pter del-dup or pure 4p terminal deletions, our observations suggest that terminal chromosome 4p deletion is more pathogenic than the concomitant partial 4p duplication, and some regions of the 4p terminal may have regulatory effects on the remaining region of 4p. About nine cases have been reported thus far to date, and our study delineates further genotype-phenotype correlations about terminal 4p duplication-deletions for predicting disease prognosis and patient counseling.

Deciphering the Invdupdel(8p) Genotype-Phenotype Correlation: Our Opinion

The 8p inverted duplication/deletion is a rare chromosomal rearrangement clinically featuring neurodevelopmental delay, mild to severe cognitive impairment, heart congenital defects and brain abnormalities. Patients affected also present typical facial dysmorphisms and skeletal malformations, and it is thought that the composite clinical picture may fall into the chromosomal rearrangement architecture. With the major aim of better framing its related clinical and diagnostic paths, we describe a patient carrying a de novo invdupde[8p] whose clinical features have not been described so far. Hence, through an extensive genotype-phenotype correlation analysis and by reviewing the dedicated scientific literature, we compared our patient's features with those reported in other patients, which allows us to place our proband's expressiveness in an intermediate area, widening the scope of the already known invdupde[8p] genotype-phenotype relationship.

Prenatal Diagnosis and Molecular Cytogenetic Characterization of Copy Number Variations on 4p15.2p16.3, Xp22.31, and 12p11.1q11 in a Fetus with Ultrasound Anomalies: A Case Report and Literature Review

Chromosomal rearrangements, such as duplications/deletions, can lead to a variety of genetic disorders. Herein, we reported a prenatal case with right aortic arch and aberrant left subclavian artery, consisting of a complex chromosomal copy number variations. Routine cytogenetic analysis described the chromosomal karyotype as 46,XY, add (2)(q37) for the fetus. However, the chromosomal microarray analysis (CMA) identified a 22.4 Mb duplication in chromosome 4p16.3p15.2, a 3.96 Mb microduplication in 12p11.1q11, and a 1.68 Mb microdeletion in Xp22.31. Fluorescence in situ hybridization (FISH) using a chromosome 4 painting probe was found to hybridize to the terminal of chromosome 2q on the fetus, thus confirming that the extra genetic materials of chromosome 2 was actually trisomy 4p detected through CMA. Meanwhile, the parental karyotypes were normal, which proved that the add (2) was de novo for fetus. The duplication of Wolf-Hirschhorn syndrome critical region (WHSCR) and X-linked recessive ichthyosis associated with Xp22.31 deletion separately were considered potentially pathogenic causes although other abnormalities involving these syndromes were not observed. For prenatal cases, the combined utilization of ultrasonography, traditional cytogenetic, and molecular diagnosis technology will enhance better diagnostic benefits, offer more detailed genetic counselling, and assess the prognosis of the fetuses.

Recombinant chromosome 4 in two fetuses - case report and literature review

Background

Recombinant chromosome 4 syndrome (rec 4 syndrome) is a rare genetic disorder, predominately resulting from a parental pericentric inversion of chromosome 4. To date, a total of 18 cases of rec (4) syndrome were published in literature. We report the first kindred of rec (4) syndrome analyzed using copy number variation sequencing (CNV-seq).

Results

A woman with two adverse fetal outcomes was described in the present study. The first fetus presented with severe intrauterine growth restriction, hyposarca, hydrothorax and ascites. The CNV-seq revealed a dup 4q and del 4p. The second fetus presented with cardiovascular disease of ventricular septal defect, overriding aorta and persistent trunk. The CNV-seq revealed a dup 4p and del 4q. We collected 18 rec (4) cases through literature review. Genotype-phenotype correlation analysis was also performed.

Conclusion

Recombinant 4 syndrome is a rare genetic disorder. It should be divided into two categories according to the alternative recombinant types. The clinical manifestations of rec (4) cases with dup 4q and del 4p are consistent with the Wolf-Hirschhorn syndrome. For cases harboring dup 4p and del 4q, the high incidence of congenital heart disease is prominent.

Relationship Between P15 Gene Mutation and Formation and Metastasis of Malignant Osteosarcoma

Background

As a type of primary malignant bone tumor, osteosarcoma has high incidence and poor prognosis, and is predisposed for pulmonary metastasis. The abnormal expression of P15 gene directly participates in the invasion of various cancers. Therefore, this study investigated the gene mutation of P15 in both primary lesion and pulmonary metastasis lesion of osteosarcoma in a rat model, in an attempt to elucidate the value of P15 gene as a biological marker.

Material/Methods

A total of 60 SD rats were randomly divided into 2 groups. Model rats had injection of osteosarcoma UMR-106 cells (5×10⁶) inoculated underneath the right forelimb skin, while control rats received saline injection instead. Six rats were sacrificed after 0, 1, 2, 4, and 6 weeks of the inoculation. Tissue samples from inoculation sites and lungs were extracted for measuring the tumor size. SP immunohistochemical (IHC) staining was used to detect the positive expression rate, while P15 gene mutation was detected by PCR method.

Results

With the elongation of inoculation time, tumor size was significantly increased (p<0.05). The positive expression rates in both primary and pulmonary metastasis lesions were also significantly elevated (p<0.05). The occurrence rate of P15 gene mutation in model rats was significantly elevated and showed a correlation with the tumor formation (r=0.998, p<0.05).

Conclusions

The P15 gene mutation was significantly correlated with osteosarcoma formation and metastasis towards the pulmonary tissue, suggesting its potency as a novel biological marker for early diagnosis of osteosarcoma.