Chromosome 18, Trisomy 18q

Last update 01 Nov 2024

Basic Info

Synonyms

18q duplication syndrome, 18q syndrome, 18q+ syndrome

+ [10]

Introduction

Duplication of the long arm of chromosome 18 with variable abnormalities, including intra-uterine growth retardation; characteristic facies with malformed ears, micrognathia, and prominent occiput; heart malformations; and psychomotor retardation.

100 Clinical Results associated with Chromosome 18, Trisomy 18q

100 Translational Medicine associated with Chromosome 18, Trisomy 18q

0 Patents (Medical) associated with Chromosome 18, Trisomy 18q

Literatures (Medical) associated with Chromosome 18, Trisomy 18q

01 Dec 2020·AACE Clinical Case Reports

Unusual Endocrinopathies in 18q Deletion Syndrome: Pseudoparathyroidism and Hyper-/Hypo-Thyroidism

Author: Lim, Whei Ying ; Bhowmick, Samar K ; Kaulfers, Anne Marie D

OBJECTIVETo describe new and unusual endocrinopathies in children with de novo 18q deletion (18q-) syndrome.METHODSWe describe 2 patients who have atypical thyroid conditions and 1 who also developed symptomatic hypocalcemia.RESULTSThe first patient developed hyperthyroidism at the age of 3 years, with a free thyroxine level of 3.9 (range, 0.8-1.8) ng/dL. Thyroid peroxidase antibodies were 262 (range, 0-32) IU/mL, and thyroid-stimulating immunoglobulin antibodies were 384% (range, 0-139%). On low-dose methimazole treatment, she developed hypothyroidism. Thyroid-stimulating hormone (TSH) level was 163 (range, 0.4-4.5) mIU/mL. Moreover, she later developed growth hormone deficiency. The second patient developed hypothyroidism at the age of 4 years, with a TSH level of 46 mIU/mL. However, TSH remained elevated at levels of 10 to 24 mIU/mL for 3 years, despite appropriate treatment, suggesting TSH resistance. She then developed hypocalcemic seizures and was diagnosed with pseudohypoparathyroidism. Her total calcium level was 6.6 (range, 8.5-10.5) mg/dL and parathyroid hormone level was 432 (range, 15-65) pg/dL.CONCLUSIONThe first patient had a mixed picture of autoimmune hypothyroidism and hyperthyroidism, requiring a combination of methimazole and levothyroxine to achieve a euthyroid state. For the second patient, the mild TSH resistance was possibly the early suggestion of a parathyroid hormone resistant state. Although growth hormone deficiency and hypothyroidism are common in patients with 18q- syndrome, the occurrence of hyperthyroidism due to Graves' disease with the coexistence of Hashimoto's hypothyroidism is rare. Pseudohypoparathyroidism has not yet been reported in patients with 18q- syndrome.

10 May 2019·Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics

[Genotypic and phenotypic analysis of a patient with de novo partial monosomy 18p and partial trisomy 18q].

Article

Author: Ye, Hui ; Liu, Yu ; Sun, Yunlong ; Cao, Ying ; Ji, Xing ; Xiao, Bing ; Qiu, Wenjuan ; Wei, Wei

OBJECTIVETo explore the genetic cause for a patient with intellectual disability, short stature and multiple congenital anomalies, and to correlate the result with the clinical phenotype.METHODSRoutine karyotyping analysis was carried out on GTG-banded metaphase chromosomes. Single nucleotide polymorphism (SNP) microarray was used to detect microdeletions or microduplications in the patient. Fluorescence in situ hybridization (FISH) was used to ascertain the origin of aberrant chromosomes.RESULTSThe karyotype of the patient was 46,XY,der(18), while both of his parents had a normal karyotype. SNP array identified a 1.23 Mb deletion at 18p11.32-pter (chr18: 136 227-1 370 501, hg19) and a 33.76 Mb duplication at 18q21.1-qter (chr18: 44 250 359-78 013 728, hg19) in the patient. Above finding was confirmed by dual-color FISH with one color for 18p and another for 18q. The patient presented with some common features of 18p deletion and 18q duplication including intellectual disability and growth retardation, in addition with some features of 18p deletion including pectus excavatum, short stature and growth hormone (GH) deficiency. The patient showed progressive improvement of stature with GH therapy. Comparison of patients with previously reported dup(18q)+del(18p) recombinations suggested that, even for patients with similar breakpoints, their phenotypes have ranged from normal to severe and there were no consistent findings.CONCLUSIONAs aberrations involving double chromosomal segments often result in phenotypic variability, it has been difficult to correlate the genotype of our patient with his phenotype.

01 Mar 2015·Molecular Medicine ReportsQ4 · MEDICINE

When Cri du chat syndrome meets Edwards syndrome

Q4 · MEDICINE

Article

Author: Chen, Baojiang ; Sun, Yunxia ; Xie, Yingjun ; Zhou, Yi ; Chen, Yongzhen ; Wu, Jianzhu

It has been well established that the 5p deletion causes Cri du chat syndrome, typically characterized by a cat‑like cry, and that duplication of 18q causes Edwards syndrome; the two are rare genetic abnormalities that separately lead to physical and mental impairments. However, the severity of the clinicopathological characteristics that arise when these two aberrations occur in one patient is unknown. Here, the first case in our knowledge of a single patient (a two‑year‑old female) with 5p partial monosomy and 18q partial trisomy is described. In the present study, chromosome microarray analysis was performed, which identified the imbalance of chromosomes 5 and 18 in the patient. The chromosome aberrations were further confirmed by fluorescence in situ hybridization. By comparing the phenotypes of combined case with those of the individual syndromes, severe clinical phenotypes of the 5p (5p15.33‑p13.3) deletion were confirmed, however, the net effect of the duplication of 18q22.3‑q23 was not determined, as this duplication only appeared to have a weak effect on the patient's phenotypes. The correlation between these chromosomal aberrations and their clinical features has implications for the identification of critical regions of 5p and 18q, particularly for the functional mapping of chromosome 18.

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Chromosome 18, Trisomy 18q

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