An unexpected finding in a child with neurological problems: mosaic ring chromosome 18

Ring 18 chromosome associated with cleft palate: case report and comprehensive literature review of clinical symptoms

BACKGROUND

Ring 18 chromosome is a rare chromosomal aberration associated with a wide range of symptoms affecting all organ systems. One possible symptom associated with this condition is an orofacial cleft. However, to date, there are very few reported cases where the cleft has been surgically treated.

CASE DESCRIPTION

In our case study, we present a female patient with Ring 18 chromosome who underwent cleft palate surgery at 14 months of age. Subsequently, a reoperation of the palate was necessary due to wound dehiscence. For the secondary reconstruction of the palate, the acellular dermal matrix (ADM) MatriDerm® was used to improve healing. The cleft palate surgery progressively improved her ability to take in food, allowing a transition from nasogastric tube feeding to oral intake.

RESULTS

This is only the fourth reported case of a child with Ring 18 chromosome undergoing surgical correction of an orofacial cleft. Additionally, it is one of the first cases where an ADM MatriDerm® was used in the surgical correction of a cleft palate. In this study, we also present a comprehensive literature review, providing an overview of the various symptoms associated with this syndrome.

CONCLUSION

Cleft palate surgery had a very positive effect on improving food intake in the patient with Ring 18 chromosome. The use of an acellular dermal matrix during the secondary cleft palate surgery led to improved healing and a good outcome.

Mosaic ring chromosome 18 in a Chinese child with epilepsy: a case report and review of the literature

BACKGROUND

Ring chromosome 18 (r[18]) is a rare syndrome in which one or both ends of chromosome 18 are lost and the remaining chromosome rejoins to form ring-shaped figures. It is characterized by developmental delay/cognitive disability, facial dysmorphisms, and immunological problems. The phenotype associated with epilepsy is rare and has not yet been reported in China.

METHODS

We report herein the case of a 12-year-old Chinese girl who presented with typical facial dysmorphisms, developmental delay, cognitive disability, hyperactivity, and epilepsy and discuss the clinical features of r(18) syndromes through comparison with previously described cases worldwide.

RESULTS

We describe the characteristics of all seizures that have been reported in these cases and propose that the appearance of epilepsy in r(18) patients may be associated with the abnormality of chromosome karyotypes. Further studies are warranted to confirm this.

A case report of Ring chromosome 18 with systemic Lupus Erythematosus and Crohn's disease

BACKGROUND

Ring Chromosome 18 is a rare chromosomal disorder caused by missing pieces of one or both ends of chromosome 18. The clinical phenotype of the Ring 18 syndrome depended on the rate and the locality of genetic material lost. Here, we report a 27 years old girl with symptoms including microcephaly, mental and motor retardation, hypotonia, and autoimmune diseases consist of Rheumatoid arthritis, Systemic Lupus Erythematosus, and Crohn's disease. This research contributes to a better understanding of disease and can lead to improvement in diagnosis and treatment.

METHOD AND RESULT

The Chromosomal analysis was performed based on the GTG banding technique on peripheral blood lymphocytes. Karyotype analysis indicated the existence of a Ring chromosome 18 with deletions at 18p11.32 and18q22-2. Following that, the parental karyotype of the affected girl confirmed that Ring 18 was caused by a de novo mistake very early in embryonic development.

CONCLUSION

Ring chromosome 18 is a rare chromosomal disorder that is generally caused by de novo errors very early in the development of the embryo. Previously studies have reported a relationship between autoimmune diseases and Ring 18. Our patient has disclosed specific types of autoimmune diseases, including Systemic Lupus Erythematosus, and Crohn's disease.

Ring chromosomes: from formation to clinical potential

Ring chromosomes (RCs) are circular DNA molecules, which occur rarely in eukaryotic nuclear genomes. Lilian Vaughan Morgan first described them in the fruit fly. Human embryos very seldom have RCs, about 1:50,000. Carriers of RCs may have varying degrees of symptoms, from healthy phenotype to serious pathologies in physical and intellectual development. Many authors describe common symptoms of RC presence: short stature and some developmental delay that could be described as a "ring chromosome syndrome." As a rule, RCs arise de novo through the end-joining of two DNA double-strand breaks, telomere-subtelomere junction, or inv dup del rearrangement in both meiosis and mitosis. There are family cases of RC inheritance. The presence of RCs causes numerous secondary chromosome rearrangements in vivo and in vitro. RCs can change their size, become lost, or increase their copy number and cause additional deletions, duplication, and translocations, affecting both RCs and other chromosomes. In this review, we examine RC inheritance, instability, mechanisms of formation, and potential clinical applications of artificially created RCs for large-scale chromosome rearrangement treatment.

Hypomyelinating disorders in China: The clinical and genetic heterogeneity in 119 patients

OBJECTIVE

Hypomyelinating disorders are a group of clinically and genetically heterogeneous diseases characterized by neurological deterioration with hypomyelination visible on brain MRI scans. This study was aimed to clarify the clinical and genetic features of HMDs in Chinese population.

METHODS

119 patients with hypomyelinating disorders in Chinese population were enrolled and evaluated based on their history, clinical manifestation, laboratory examinations, series of brain MRI with follow-up, genetic etiological tests including chromosomal analysis, multiplex ligation probe amplification, Sanger sequencing, targeted enrichment-based next-generation sequencing and whole exome sequencing.

RESULTS

Clinical and genetic features of hypomyelinating disorders were revealed. Nine different hypomyelinating disorders were identified in 119 patients: Pelizaeus-Merzbacher disease (94, 79%), Pelizaeus-Merzbacher-like disease (10, 8%), hypomyelination with atrophy of the basal ganglia and cerebellum (3, 3%), GM1 gangliosidosis (5, 4%), GM2 gangliosidosis (3, 3%), trichothiodystrophy (1, 1%), Pol III-related leukodystrophy (1, 1%), hypomyelinating leukodystrophy type 9 (1, 1%), and chromosome 18q deletion syndrome (1, 1%). Of the sample, 94% (112/119) of the patients were genetically diagnosed, including 111 with mutations distributing across 9 genes including PLP1, GJC2, TUBB4A, GLB1, HEXA, HEXB, ERCC2, POLR3A, and RARS and 1 with mosaic chromosomal change of 46, XX,del(18)(q21.3)/46,XX,r(18)(p11.32q21.3)/45,XX,-18. Eighteen novel mutations were discovered. Mutations in POLR3A and RARS were first identified in Chinese patients with Pol III-related leukodystrophy and hypomyelinating leukodystrophy, respectively.

SIGNIFICANCE

This is the first report on clinical and genetic features of hypomyelinating disorders with a large sample of patients in Chinese population, identifying 18 novel mutations especially mutations in POLR3A and RARS in Chinese patients, expanding clinical and genetic spectrums of hypomyelinating disorders.

Molecular characterization and evaluation of complex rearrangements in a case of ring chromosome 15

Background

Ring chromosome 15 is a rare genetic entity. Only a few cases have been reported with characterization using molecular techniques. The clinical presentation is quite variable, as a result of differences in the breakpoints, haploinsufficiency of genes involved in deleted segment/s, level of mosaicism and ring instability resulting in a variability of rearrangement of genetic material.

Case presentation

The proband, a 2 months old boy, presented with small head size and facial dysmorphism. On examination microcephaly, triangular face, small anterior frontanelle, micrognathia, hypotonia, unilateral simian crease, hypertelorism, umbilical hernia, micropenis with mild phimosis were noted. Karyotype revealed 46,XY,r(15)(p11.2q26). Array-comparative genomic hybridization (aCGH) and targeted gene sequencing for microcephaly was carried out for genotype phenotype correlation. Array-CGH detected a 2.8 Mb terminal deletion at 15q26.3 along with a 496 kb interstitial micro-duplication, encompassing the IGF1R gene, in the affected genomic region, which was otherwise missed on conventional karyotype.

Conclusion

The present study highlights the importance of aCGH in not only delineating specific phenotypes through accurate genotypic correlation but also in detection and evaluation of ring chromosome with unexpected complex rearrangements.

Electronic supplementary material

The online version of this article (10.1186/s13039-017-0339-z) contains supplementary material, which is available to authorized users.

Chromosome abnormalities in Indonesian patients with short stature

Background

Short stature is associated with several disorders including wide variations of chromosomal disorders and single gene disorders. The objective of this report is to present the cytogenetic findings in Indonesian patients with short stature.

Methods

G-banding and interphase/metaphase FISH were performed on short stature patients with and without other clinical features who were referred by clinicians all over Indonesia to our laboratory during the year 2003–2009.

Results

The results of chromosomal analysis of ninety seven patients (mean age: 10.7 years old) were collected. The group of patients with other clinical features showed sex chromosome abnormalities in 45% (18/40) and autosomal abnormalities in 10% (4/40), whereas those with short stature only, 42.1% (24/57) had sex chromosome abnormalities and 1.75% (1/57) had autosomal abnormalities. The autosomal chromosomal abnormalities involved mostly subtelomeric regions. Results discrepancies between karyotype and FISH were found in 10 patients, including detection of low-level monosomy X mosaicism in 6 patients with normal karyotype, and detection of mosaic aneuploidy chromosome 18 in 1 patient with 45,XX,rob(13;14)(q10;q10).

Statistical analysis showed no significant association between the groups and the type of chromosomal abnormalities.

Conclusion

Chromosome abnormalities account for about 50% of the short stature patients. Wide variations of both sex and autosomal chromosomes abnormalities were detected in the study. Since three out of five patients had autosomal structural abnormalities involving the subtelomeric regions, thus in the future, subtelomeric FISH or even a more sensitive method such as genomic/SNP microarray is needed to confirm deletions of subtelomeric regions of chromosome 9, 11 and 18. Low-level mosaicism in normal karyotype patients indicates interphase FISH need to be routinely carried out in short stature patients as an adjunct to karyotyping.

De novo mosaic ring chromosome 18 in a child with mental retardation, epilepsy and immunological problems

Ring chromosome 18 [r(18)] is a disorder in which one or both ends of chromosome 18 are lost and joined forming a ring-shaped figures. R(18) patients can therefore show features of 18q-, 18p- syndrome or a combination of both, depending on the size of the 18p and 18q deleted regions. The phenotype of the r(18) is characterized by developmental delay/mental retardation, typical facial dysmorphisms, major abnormalities and immunological problems. Here we report a case of de novo mosaic r(18) with a characterization by array-based comparative genomic hybridization analysis, and discuss the phenotypic correlation in r(18) also through a comparison with previously described cases of the literature.

Somatic mosaicism in cases with small supernumerary marker chromosomes

Somatic mosaicism is something that is observed in everyday lives of cytogeneticists. Chromosome instability is one of the leading causes of large-scale genome variation analyzable since the correct human chromosome number was established in 1956. Somatic mosaicism is also a well-known fact to be present in cases with small supernumerary marker chromosomes (sSMC), i.e. karyotypes of 47,+mar/46. In this study, the data available in the literature were collected concerning the frequency mosaicism in different subgroups of patients with sSMC. Of 3124 cases with sSMC 1626 (52%) present with somatic mosaicism. Some groups like patients with Emanuel-, cat-eye- or i(18p)- syndrome only tend rarely to develop mosaicism, while in Pallister-Killian syndrome every patient is mosaic. In general, acrocentric and non-acrocentric derived sSMCs are differently susceptible to mosaicism; non-acrocentric derived ones are hereby the less stable ones. Even though, in the overwhelming majority of the cases, somatic mosaicism does not have any detectable clinical effects, there are rare cases with altered clinical outcomes due to mosaicism. This is extremely important for prenatal genetic counseling. Overall, as mosaicism is something to be considered in at least every second sSMC case, array-CGH studies cannot be offered as a screening test to reliably detect this kind of chromosomal aberration, as low level mosaic cases and cryptic mosaics are missed by that.

Ring chromosome instability evaluation in six patients with autosomal rings

Ring chromosomes are often associated with abnormal phenotypes due to loss of genomic material and also because of ring instability at mitosis after sister chromatid exchange events. We investigated ring chromosome instability in six patients with ring chromosomes 4, 14, 15, and 18 by examining 48- and 72-h lymphocyte cultures at the first, second and subsequent cell divisions after bromodeoxyuridine incorporation. Although most cells from all patients showed only one monocentric ring chromosome, ring chromosome loss and secondary aberrations were observed both in 48- and 72-h lymphocyte cultures and in metaphase cells of the different cell generations. We found no clear-cut correlation between ring size and ring instability; we also did not find differences between apparently complete rings and rings with genetic material loss. The cytogenetic findings revealed secondary aberrations in all ring chromosome patients. We concluded that cells with ring chromosome instability can multiply and survive in vivo, and that they can influence the patient's phenotype.

A case of ring chromosome 18 syndrome treated with a combined orthodontic-prosthodontic approach

OBJECTIVE

The aim of this study was to report the case of a Japanese subject with ring chromosome 18 syndrome. A cephalometric analysis was performed, and the treatment procedure is described.

DESIGN

Lateral and posteroanterior cephalograms were compared with Japanese norms. Dental anomalies were evaluated by a model analysis. The outcome of orthodontic-prosthodontic treatment was evaluated by comparing cephalograms during the course of treatment.

RESULTS

The cephalometric analysis showed a reduction in the cranial base length and cranial width, midfacial depth, and height and width. Comparison of lateral cephalograms at age 16 years 6 months and 22 years 4 months showed late growth of the mandible. The model analysis showed that all of the teeth, except for the mandibular canine, were small.

CONCLUSIONS

Characteristic craniofacial and dental anomalies were clarified. Successful oral rehabilitation was achieved by combined orthodontic-prosthodontic treatment.