7 Mb de novo deletion within 8q21 in a patient with distal arthrogryposis type 2B (DA2B)

Arthrogryposis multiplex congenita: dental and maxillofacial phenotype - A scoping review

INTRODUCTION

Arthrogryposis multiplex congenita (AMC) is a heterogeneous group of disorders associated with decreased fetal movement, with a prevalence between 1/3000 and 1/5200 live births. Typical features of AMC include multiple joint contractures present at birth, and can affect all joints of the body, from the jaw, and involving the upper limbs, lower limbs and spine. The jaws may be affected in 25 % of individuals with AMC, with limited jaw movement and mouth opening. Other oral and maxillofacial deformities may be present in AMC, including cleft palate, micrognathia, periodontitis and delayed teething. To our knowledge, oral and maxillofacial abnormalities have not been systematically assessed in individuals with AMC. Therefore, this scoping review was conducted to identify, collect, and describe a comprehensive map of the existing knowledge on dental and maxillofacial involvement in individuals with AMC.

METHODOLOGY

A scoping review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews guidelines. The PRISMA guidelines for scoping reviews were followed and databases were searched for empirical articles in English and French published until October 2022. We searched MEDLINE, Embase, Web of Science and ERIC databases. Two authors independently reviewed the articles and extracted the data.

RESULTS

Of a total of 997 studies that were identified, 96 met the inclusion criteria and were subsequently included in this scoping review. These 96 studies collectively provided insights into 167 patients who exhibited some form of oral and/or maxillofacial involvement. Notably, 25 % of these patients were within the age range of 0-6 months. It is worth highlighting that only 22 out of the 96 studies (22.9 %), had the primary objective of evaluating dental and/or maxillofacial deformities. Among the patients studied, a prevalent pattern emerged, revealing that severe anomalies such as micrognathia (56 %), high-arched palate (29 %), cleft palate (40 %), limited mouth opening (31 %), and dental anomalies (28 %) were frequently observed. Importantly, many of these patients were found to have more than one of these anomalies. Even though these maxillofacial impairments are known to be associated with dental problems (e.g., cleft palate is associated with oligodontia, hypodontia, and malocclusion), their secondary effects on the dental phenotype were not reported in the studies.

CONCLUSION

Our findings have uncovered a notable deficiency in existing literature concerning dental and maxillofacial manifestations in AMC. This underscores the need for interdisciplinary collaboration and the undertaking of extensive prospective cohort studies focused on AMC. These studies should assess the oral and maxillofacial abnormalities that can impact daily functioning and overall quality of life.

Congenital corneal staphyloma in 8q21.11 microdeletion syndrome

BACKGROUND

Although 8q21.11 microdeletion syndrome (8q21.11 DS) has been reported in association with congenital corneal opacities, reports of the clinicopathological features and management are scarce.

METHODS

We reviewed medical records including ophthalmic evaluations, imaging, operative reports, and pathology reports of two unrelated patients referred to the Ophthalmology Clinic of UPMC Children's Hospital of Pittsburgh with a cytogenetic diagnosis of 8q21.11 DS.

RESULTS

Ophthalmological evaluation of both children revealed bilateral enlarged, staphylomatous, and cloudy corneas with neovascularization. These findings were consistent with the diagnosis of congenital corneal staphyloma (CCS). In one patient, anterior segment optical coherence tomography and high-frequency ultrasound revealed materials consistent with lens remnants embedded in the cornea; this was confirmed by histopathology. In the second patient, lens was found to be adherent to the cornea during surgery. One eye underwent enucleation for corneal perforation secondary to elevated intraocular pressure. In the other eyes, treatment consisted of penetrating keratoplasty combined with vitrectomy. Ahmed tube was subsequently placed to control intraocular pressure.

CONCLUSION

8q21.11 microdeletion syndrome can be associated with bilateral CCS, likely related to a combination of anterior segment developmental anomalies and elevated intraocular pressure. Tectonic penetrating keratoplasty is necessary to prevent corneal perforation, together with a strict control of the intraocular pressure.

T-cell Lymphoblastic Lymphoma in a Patient With Chromosome 8q21.11 Microdeletion

The chromosome 8q21.11 deletion syndrome is an extremely rare genetic condition characterized by facial dysmorphic features, Peters anomaly and impaired intellectual development. We report a case of a 2-year-old female with chromosome 8q21.11-q21.2 microdeletion complicated by T-cell lymphoblastic lymphoma. Whole genome single-nucleotide polymorphism microarray detected an interstitial deletion of 8q21.11 to q.21.2, including 16 genes. Autopsy findings revealed a T-cell lymphoblastic lymphoma presenting as an anterior mediastinal mass, encroaching upon the aortic arch, left subclavian artery, left carotid bifurcation and trachea. The genes that may contribute to a neoplastic process are identified (PKIA, IL7, TPD52, PAG1, and FABP5) and discussed in this article.

8q21.11 microdeletion syndrome: Delineation of HEY1 as a candidate gene in neurodevelopmental and cardiac defects

BACKGROUND

8q21.11 microdeletion syndrome is a rare chromosomal disorder characterized by recurrent dysmorphic features, a variable degree of intellectual disability and ocular, cardiac and hand/feet abnormalities. To date, ZFHX4 is the only candidate gene implicated in the ocular findings. In this study, we evaluated a patient with a de novo 8q21.13-21.3 deletion to define a new small region of overlap (SRO) for this entity.

METHODS

We conducted a clinical evaluation and comparative genomic hybridization (CGH) 4x44K microarrays in a patient with de novo unbalanced translocation t(8;16)(q21; q11.2).

RESULTS

The case, a 6-year-old boy, presented dysmorphic features including an elongated face, brachycephaly with a high forehead, an underdeveloped ala, thin upper lip, micrognathia, low-set ears, hypotonia, mild intellectual disability, cortical atrophy with thin corpus callosum defect, and an atrial septal defect. No ocular abnormalities were found. Microarray analysis revealed a 9.6 Mb interstitial 8q21.11-21.3 deletion, not including the ZFHX4 gene. This microdeletion was confirmed in our patient through qPCR analysis, and both parents had a normal profile. Alignment analysis of our case defined a new SRO encompassing five genes. Among them, the HEY1 gene is involved in the embryonic development of the heart, central nervous system, and vascular system. Hrt1/Hey1 null mice show perinatal lethality due to congenital malformations of the aortic arch and its branch arteries. HEY1 has also been linked to the maintenance of neural stem cells, inhibition of oligodendrocyte differentiation, and myelin gene expression.

CONCLUSION

HEY1 is a candidate gene for both neurological and cardiac features of the 8q21.11 microdeletion syndrome and might, therefore, explain specific components of its pathophysiology.

A ZFHX4 mutation associated with a recognizable neuropsychological and facial phenotype

Several patients with chromosomal deletions including ZFHX4 gene have been described, whereas point mutations are very rare. This gene encodes for a transcription factor involved in the development of several embryonal processes, including brain differentiation. Patients with 8q21.11 deletions usually show intellectual disability, short stature, peculiar facial features, and severe eye abnormalities. We describe a female patient with mild intellectual disability, autism spectrum disorder, strabismus, ptosis, low-set and prominent ears, high-arched palate, microretrognathia. Clinical Exome Sequencing revealed the presence of a de novo heterozygous variant in ZFHX4. Therefore, we further investigate the different phenotypes of ZFHX4 mutations and 8q21.11 deletions.

8q21.11 microdeletion in two patients with syndromic peters anomaly

Peters anomaly is a form of anterior segment dysgenesis characterized by central ocular opacity and corneo-lenticular adhesions. Isolated and syndromic Peters anomaly can be observed and demonstrate significant genetic heterogeneity. We report the identification of overlapping 8q21.11 deletions in two patients with syndromic Peters anomaly via whole exome sequencing and chromosomal microarray analyses. Microdeletions of 8q21.11 were recently reported in 10 patients with highly variable phenotypes involving craniofacial features, ptosis, intellectual disability, abnormalities of the hands/feet and other defects; sclerocornea and/or microphthalmia were reported in three cases. The two additional cases presented in this report expand the phenotypic spectrum of 8q21.11 microdeletions to include Peters anomaly (seen in both patients) and persistent primary dentition (seen in one patient with a larger deletion). The two novel deletions include the ZFHX4 and PEX2 genes, which were also affected in all three previous cases involving ocular anomalies. Screening of the remaining alleles of ZFHX4 and PEX2 did not identify any additional likely pathogenic variants in either patient, suggesting a dominant mechanism (haploinsufficiency) for the identified deletion. This report provides further insight into the phenotypes associated with 8q21.11 deletions and, for the first time, reports Peters anomaly as an additional ocular feature; screening for copy number variations of the 8q21.11 region should be considered in patients with Peters anomaly and related syndromic features. © 2016 Wiley Periodicals, Inc.

Clinical characterization of a male patient with the recently described 8q21.11 microdeletion syndrome

The 8q21.11 microdeletion syndrome (OMIM # 614230) has been recently described and is primarily characterized by intellectual disability and facial dysmorphism. We describe here a male patient of 9 years 9 months of age with moderate intellectual disability and dysmorphic facial features. A high resolution copy number variation analysis, performed with the Affymetrix Cytogenetics Whole-Genome 2.7 M SNP array, allowed the identification of a heterozygous 7.069 Mb microdeletion at chromosome 8q21.11-q21.13. Clinical comparison of our patient with literature shows many similarities. However, the whole facial appearance of our patient, especially the elongated rather than rounded face and the absence of a wide nasal bridge and epicanthal folds, confers him a phenotype similar only to a subset, but not to the majority, of the hitherto described patients.