Case report of de novo dup(18p)/del(18q) and r(18) mosaicism

Chromosome Abnormalities Related to Reproductive and Sexual Development Disorders: A 5-Year Retrospective Study

Chromosomal abnormalities are the main genetic risk factor associated with reproductive and sexual development disorders (DSD). The goal of this study is to retrospectively evaluate the frequency of chromosomal aberrations in Moroccan subjects with problems of procreation or sexual ambiguity. A total of 1005 individuals, including 170 infertile couples, underwent cytogenetic analysis in the Cytogenetic Laboratory of the Pasteur Institute of Morocco. Heparinized blood samples were processed according to the standard karyotype method. A total (81.5%) of the patients studied had a normal karyotype, while the remaining (18.5%) patients had an abnormal karyotype. Female patients had more chromosomal abnormalities (52%) than male patients (48%). These chromosomal aberrations included 154 cases (83%) of sex chromosomal abnormalities, the most common being Turner's syndrome and Klinefelter's syndrome, and 31 cases (17%) had autosomal aberrations, especially chromosome 9 reversal (inv(9)(p12;q13)). The present data shows that among 170 couples, 10.6% had chromosomal abnormalities mainly involved in the occurrence of recurrent miscarriages. Genotype-phenotype correlations could not be made, and therefore, studies using more resolutive molecular biology techniques would be desirable.

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.

Two Distinctively Rare Syndromes in a Case of Primary Amenorrhea: 18p Deletion and Mayer-Rokitansky-Kuster-Hauser Syndromes

Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome and 18p deletion syndrome, two genetic disorders having distinct genetic etiologies, have an exceedingly rare likelihood of coexistence. Vaginal agenesis or MRKH syndrome, the developmental failure of Mullerian ductal system-derived structures in a genotypic female fetus (46, XX), leads to congenital absence of uterus and vagina in variable degree. The 18p deletion syndrome is a rare chromosomal disorder, characterized by dysmorphic features, stunted growth, and mental retardation, which is caused by deletion of a part or all of the short arm of chromosome 18. A detailed evaluation of primary amenorrhea in a 16-year-old girl yielded both MRKH syndrome and 18p deletion syndrome. Extensive literature search could not identify any reported case bearing this combination of syndromes. This case presentation and review emphasizes on the importance of karyotyping in MRKH patients having atypical features.

Investigation of Chromosomal Abnormalities and Microdeletion/ Microduplication(s) in Fifty Iranian Patients with Multiple Congenital Anomalies

Objective

Major birth defects are inborn structural or functional anomalies with long-term disability and adverse impacts on individuals, families, health-care systems, and societies. Approximately 20% of birth defects are due to chromosomal and genetic conditions. Inspired by the fact that neonatal deaths are caused by birth defects in about 20 and 10% of cases in Iran and worldwide respectively, we conducted the present study to unravel the role of chromosome abnormalities, including microdeletion/microduplication(s), in multiple congenital abnormalities in a number of Iranian patients.

Materials and Methods

In this descriptive cross-sectional study, 50 sporadic patients with Multiple Congenital Anomalies (MCA) were selected. The techniques employed included conventional karyotyping, fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), and array comparative genomic hybridisation (array-CGH), according to the clinical diagnosis for each patient.

Results

Chromosomal abnormalities and microdeletion/microduplication(s) were observed in eight out of fifty patients (16%). The abnormalities proved to result from the imbalances in chromosomes 1, 3, 12, and 18 in four of the patients. However, the other four patients were diagnosed to suffer from the known microdeletions of 22q11.21, 16p13.3, 5q35.3, and 7q11.23.

Conclusion

In the present study, we report a patient with 46,XY, der(18)[12]/46,XY, der(18), +mar[8] dn presented with MCA associated with hypogammaglobulinemia. Given the patient’s seemingly rare and highly complex chromosomal abnormality and the lack of any concise mechanism presented in the literature to justify the case, we hereby propose a novel mechanism for the formation of both derivative and ring chromosome 18. In addition, we introduce a new 12q abnormality and a novel association of an Xp22.33 duplication with 1q43q44 deletion syndrome. The phenotype analysis of the patients with chromosome abnormality would be beneficial for further phenotype-genotype correlation studies.

Hypothyroidism and levothyroxine-responsive liver dysfunction in a patient with ring chromosome 18 syndrome

BACKGROUND

Ring chromosome 18 [r18] is a rare constitutional chromosomal aberration syndrome, characterized by dysmorphic face, hypoactivity, short stature, and delayed development. Autoimmune thyroiditis and immunoglobulin (Ig) A deficiency are occasionally associated with chromosome-18 deletion syndromes.

SUMMARY

Here, we report a 2-year-old male child with r(18) syndrome and a selective IgA deficiency (<1.6 mg/dL, reference range [rr]: 20-149), who developed hypothyroidism and liver dysfunction. Thyroid function tests (thyroid-stimulating hormone [TSH]: 1031 μIU/mL, rr 0.43-4.0; free triiodothyronine: 0.52 pg/mL, rr 2.37-4.65; free thyroxine: 0.11 ng/dL, rr 1.03-2.00) and positive thyroid antibodies (anti-TSH receptor 1.7 IU/L, cut-off index [coi]: <1.0, antithyroid peroxidase 171 IU/mL, coi <0.3, and antithyroglobulin 2.8 IU/mL, coi <0.3) indicated autoimmune hypothyroidism. Elevated levels of aspartate aminotransferase (AST, 240 IU/L, rr 17-39) and alanine aminotransferase (ALT, 315 IU/L, rr 4-23), but negative antibodies against LKM and mitochondrial M2, suggested no autoimmune hepatitis. Transaminase levels became normalized after he was given levothyroxine therapy to achieve the euthyroid state, but they repeatedly became elevated when levothyroxine was inadvertently discontinued (peak AST=409 IU/L; peak ALT=390 IU/L). A maintenance dose of levothyroxine has effectively maintained the euthyroid state and normalized liver function tests despite no immunosuppressive therapy.

CONCLUSIONS

The r18 patient with autoimmune hypothyroidism and IgA deficiency suffered from idiopathic hepatitis. The liver dysfunction was associated with hypothyroidism that resolved with thyroid hormone treatment. While the former combination has been described, the latter has not. The reason for the development of hepatitis in association with hypothyroidism is unexplained. However, we postulate that it might be related, in ways that are not clear, to the deleted genes of r18.

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.

Implications of prenatal diagnosis of the fetus with both interstitial deletion and a small marker ring originating from chromosome 5

We describe a patient with 47,XY,del(5)(p11p13), +mar observed in prenatal screening. We performed analyses including G-banding, multi-color fluorescent in situ hybridization (mFISH) for fetal chromosome detection. After birth array-based comparative genomic hybridization (aCGH), bacterial artificial chromosome (BAC)-FISH was carried out to define the chromosomal changes precisely. The mFISH revealed that a ring chromosome that had originated from chromosome 5. The aCGH showed that this fetus had a terminal duplication, an interstitial deletion, and a pericentromeric duplication of the short arm of chromosome 5. This complex alteration resulted in partial trisomy 5p15.33-p15.31, partial monosomy 5p14.3-p13.2, and partial trisomy 5p12-p11. To clarify these alterations, we performed BAC-FISH using BAC clones related to deleted and duplicated regions, and found that a derivative (der) chromosome 5 showed the presence of hybridization signals from the duplicated region at 5p15.33 and the loss of hybridization signals from the deleted region at 5p14.2. In addition, FISH analysis confirmed the origin of the marker chromosome. Hybridization signals from the second intervening sequence at 5p13.1, between the deleted region and the pericentric duplicated region, were present on the marker ring chromosome.