Hallermann-Streiff syndrome: A missing molecular link for a highly recognizable syndrome

The Secondary Childhood Glaucomas

The secondary childhood glaucomas are a heterogenous group, often associated with other ocular or systemic abnormalities. These childhood glaucomas are distinct from primary childhood glaucomas, both in terms of their clinical features and their response to conventional treatment. Surgical management can be challenging in children with secondary glaucoma. On average, this group undergo more surgical procedures and revisions than those with primary congenital glaucoma. We provide a synopsis of secondary childhood glaucomas in terms of classification, clinical features, and management strategies, with emphasis on recent developments.

Mechanical stress can regulate temporomandibular joint cavitation via signalling pathways

The temporomandibular joint (TMJ), composed of temporal fossa, mandibular condyle and a fibrocartilage disc with upper and lower cavities, is the biggest synovial joint and biomechanical hinge of the craniomaxillofacial musculoskeletal system. The initial events that give rise to TMJ cavities across diverse species are not fully understood. Most studies focus on the pivotal role of molecules such as Indian hedgehog (Ihh) and hyaluronic acid (HA) in TMJ cavitation. Although biologists have observed that mechanical stress plays an irreplaceable role in the development of biological tissues and organs, few studies have been concerned with how mechanical stress regulates TMJ cavitation. Based on the evidence from human or other animal embryos today, it is implicated that mechanical stress plays an essential role in TMJ cavitation. In this review, we discuss the relationship between mechanical stress and TMJ cavitation from evo-devo perspectives and review the clinical features and potential pathogenesis of TMJ dysplasia.

Paediatric cataract surgery with 27G vitrectomy instrumentation: the Ghent University Hospital Experience

Objective

To describe a cohort of paediatric patients who underwent unilateral or bilateral lens extractions at Ghent University hospital using the Dutch Ophthalmic Research Center (D.O.R.C.) ultra-short 27G vitrectomy system.

Methods

Retrospective analysis of the medical and surgical records of all children that underwent lens extraction between September 2016 and September 2020 using the D.O.R.C. ultra-short 27G vitrectomy system.

Results

Seventy-two eyes of 52 patients were included. The most important aetiologies in this study were of secondary (25.5%), developmental (13.7%), or genetic (13.7%) nature. No definitive cause could be established in more than a quarter of cases (27.5%) despite extensive work-up, them being deemed idiopathic. The remainder of cases (19.6%) was not assigned a final aetiologic designation at the time of the study due to contradicting or missing diagnostic data. This study could not identify any cataract cases related to infection or trauma. Surgical complications rate was 61.1% of which posterior capsule opacification was the most frequent with a rate of 25%. A significant short-term postoperative best-corrected visual acuity gain (≤ -0.2 LogMAR) was observed in 60.5% of eyes for which usable acuity data were available (n = 38).

Conclusion

Many different instruments and techniques have been described and used in the context of paediatric lens extractions, each with its advantages and disadvantages. This study illustrates that an ultra-short 27G vitrectomy system can be used to perform paediatric lens extractions with good surgical outcomes. Further studies and comparative trials are needed to ascertain this further.

Hallermann-Streiff Syndrome in Concordant Monozygotic Twins With Congenital Cataracts, Exudative Retinal Detachments, and One Case of Corneal Perforation Requiring Keratoplasty

PURPOSE

We describe the management of Hallermann-Streiff syndrome in monozygotic female twins with congenital cataracts, exudative retinal detachments, and 1 case of corneal descemetocele with associated dellen and subsequent perforation.

METHODS

This study was a case report and review of the literature.

RESULTS

Twins 1 and 2 exhibited all 7 cardinal characteristics of Hallermann-Streiff syndrome, presenting with spontaneous lenticular resorption, anterior uveitis, and glaucoma. They underwent bilateral cataract extraction with near total capsulectomy. Both twins experienced recurrent glaucoma, for which twin 1 underwent successful endocyclophotocoagulation in both eyes and twin 2 in the left eye alone. The fellow eye developed 2 sites of perilimbal corneal descemetoceles with associated dellen at the inferotemporal limbal corneal junction leading to spontaneous perforation of 1 site, requiring a full-thickness corneal graft. Both twins developed recurrent bilateral exudative retinal detachments unresponsive to oral prednisolone. Twin 1's last best-corrected visual acuity with aphakic spectacles was 20/260 in the right eye and 20/130 in the left eye at age 4 years and 8 months. Twin 2's last best-corrected visual acuity was 20/130 in each eye at age 4 years and 11 months, over a year after right eye penetrating keratoplasty.

CONCLUSIONS

We describe 2 rare cases of Hallermann-Streiff syndrome in monozygotic twins complicated by corneal perforation requiring penetrating keratoplasty in 1 eye of 1 twin. Although corneal opacities have been described in this condition, this is the first case of corneal descemetocele in Hallermann-Streiff syndrome. The cornea was stabilized with a relatively favorable visual outcome over 1 year later.

Hallermann–Streiff Syndrome and Lower Limb Lymphedema with Nasal Obstruction

Background. Hallermann–Streiff syndrome (HSS) is a rare congenital abnormality involving multiple craniofacial malformations, such as micrognathia, prominent frontal and nasal bones, vision defects, and dental anomalies, which can result in obstructive sleep apnea syndrome. The aim of the present study was to report a case of nasal obstruction in an individual with Hallermann–Streiff syndrome who had never breathed through the nose during treatment for lower limb lymphedema involving cervical lymphatic therapy. Case Report. An 18-year-old female adolescent with a diagnosis of HSS was sent from the genetics service of a teaching school for the treatment of lower limb lymphedema. At around 11 years of age, the patient began to present edema in the left leg, accompanied by broadening of the face and neck. The patient reported having obstructed nostrils and breathing through the mouth her entire life. On the second day of treatment, the patient reported being able to breathe through one of the nostrils, this had never occurred before. Based on this finding, the decision was made to include linear facial lymphatic drainage using the Godoy method, which led to the complete resolution of the nasal obstruction in the first 15 minutes of treatment. Nasal obstruction in children with Hallermann–Streiff syndrome may be caused by lymphedema. Conclusion. A specific lymphatic drainage technique, such as cervical lymphatic therapy and facial linear lymphatic therapy, can resolve the obstruction and maintain the nostrils unblocked for months.

Long term NIV in an infant with Hallermann-Streiff syndrome: A case report and overview of respiratory morbidity

Hallermann-Streiff syndrome (HSS) is a rare congenital syndrome with different anomalies including midface hypoplasia, beak nose and micrognathia. The upper airways narrowness can lead to severe respiratory complications such as obstructive sleep apnoea syndrome (OSAS), particularly in infancy. The management of these severe OSAS is difficult and poorly documented in literature. We report the case of an infant with HSS complicated by severe and early OSAS successfully managed with non-invasive ventilation (NIV), provide an overview of respiratory morbidities and discuss treatment options for HSS-related OSAS.

Hallermann–Streiff syndrome: Case report with abnormal pulp calcifications

Hallermann–Streiff syndrome (HSS) is a disorder of rare occurrence affecting the craniofacial complex, with approximately 200 cases reported in the literature. Nonetheless, its distinctive facial features render it highly recognizable. We present the case of a 5-year-old girl with this syndrome and review the dental manifestations and management in this patient. In addition to the diagnostic facial features of brachycephaly with frontal bossing, beak-shaped nose, microphthalmia, and mandibular retrusion, multiple dental manifestations were noted, including the absence of the mandibular condyle, ghost teeth, and unusual pulpal calcifications in both the primary and the permanent teeth, which have not been previously reported in a case of HSS. There is no consensus on the suitable treatment plan to be given for HSS patients from a young age due to an underreporting of these cases in the literature. In this report, we discuss pediatric dental management options for a patient with HSS and share her perspective of the treatment.

Variation in Middle Stone Age mandibular molar enamel-dentine junction topography at Klasies River Main Site assessed by diffeomorphic surface matching

The morphology and variability of the Middle Stone Age (MSA) hominin fossils from Klasies River Main Site have been the focus of investigation for more than four decades. The mandibular remains have figured prominently in discussions relating to robusticity, size dimorphism, and symphyseal morphology. Variation in corpus size between the robust SAM-AP 6223 and the diminutive SAM-AP 6225 mandibles is particularly impressive, and the difference between the buccolingual diameters of their M₂s significantly exceeds recent human sample variation. SAM-AP 6223 and SAM-AP 6225 are the only Klasies specimens with homologous teeth (M₂ and M₃) that permit comparisons of crown morphology. While the differences in dental trait expression at the outer enamel surfaces of these molars are slight, diffeomorphic surface analyses of their underlying enamel-dentine junction (EDJ) topographies reveal differences that are well beyond the means of pairwise differences among comparative samples of Later Stone Age (LSA) Khoesan and recent African homologues. The EDJs of both SAM-AP 6225 molars and the SAM-AP 6223 M₃ fall outside the envelopes that define the morphospace of these two samples. Although the radiocarbon dated LSA individuals examined here differ by a maximum of some 7000 years, and the two Klasies jaws may differ by perhaps as much as 18,000 years, it is difficult to ascribe their differences to time alone. With reference to the morphoscopic traits by which the SAM-AP 6223 and SAM-AP 6225 EDJs differ, the most striking is the expression of the protoconid cingulum. This is very weakly developed on the SAM-AP 6223 molars and distinct in SAM-AP 6225. As such, this diminutive fossil exhibits a more pronounced manifestation of what is likely a plesiomorphic feature, thus adding to the morphological mosaicism that is evident in the Klasies hominin assemblage. Several possible explanations for the variation and mosaicism in this MSA sample are discussed.

A Novel Homozygous Variant in GJA1 Causing a Hallermann-Streiff/Oculodentodigital Dysplasia Overlapping Phenotype: A Clinical Report

This paper reports the case of a Moroccan girl with a phenotype within the clinical spectrum of both Hallermann-Streiff (HSS, OMIM 234100) and Oculodentodigital Dysplasia (ODDD, OMIM 164200) syndromes. The patient presented with repeated dental abscesses and severe early childhood caries. She had no learning deficit nor psychomotor regression; however, a language delay was noted. She also presented with obstructive sleep apnea syndrome and specific craniofacial features pathognomonic of HSS. Radiographic examination showed enamel and dentin defects, giving a ghost-like tooth appearance. Several clinical features of ODDD overlap those of HSS and may confuse diagnosis, considering that the inheritance of HSS is not described yet. The diagnostic odyssey of this patient ended with the identification by exome sequencing of a novel homozygous alteration in the GJA1 gene. A missense substitution in exon 2 [Chr6(GRCh37): g.121768554C>G NM_000165.4: c.561C>G p.Cys187Trp] was identified by whole-exome sequencing (WES), suggesting a diagnosis of ODDD. This is the first report of a homozygous mutation affecting the second extracellular loop of the CX43 protein.

Overarching control of autophagy and DNA damage response by CHD6 revealed by modeling a rare human pathology

Members of the chromodomain-helicase-DNA binding (CHD) protein family are chromatin remodelers implicated in human pathologies, with CHD6 being one of its least studied members. We discovered a de novo CHD6 missense mutation in a patient clinically presenting the rare Hallermann-Streiff syndrome (HSS). We used genome editing to generate isogenic iPSC lines and model HSS in relevant cell types. By combining genomics with functional in vivo and in vitro assays, we show that CHD6 binds a cohort of autophagy and stress response genes across cell types. The HSS mutation affects CHD6 protein folding and impairs its ability to recruit co-remodelers in response to DNA damage or autophagy stimulation. This leads to accumulation of DNA damage burden and senescence-like phenotypes. We therefore uncovered a molecular mechanism explaining HSS onset via chromatin control of autophagic flux and genotoxic stress surveillance.

Fifty years of recognizable patterns of human malformation: Insights and opportunities

Now in its 7th edition, Smith's Recognizable Patterns of Human Malformation was first published in 1970. This 1st edition comprised 135 "dysmorphic syndromes of multiple primary defects" and 12 "single syndromic malformations resulting in secondary defects." Of the former, other than a few chromosomal and environmental disorders, most were heritable conditions of then unknown etiology. In 2021, the majority of these conditions are now "solved," a notable exception is Hallermann-Streiff syndrome. The "solved" conditions were typically clinically delineated decades prior to understanding the underlying etiology, which rarely required recent technologies such as exome sequencing (ES) to elucidate. The 7th edition includes nearly 300 syndromes, sequences, and associations. An increasing number of conditions first appearing in the latest editions are sporadic, with many solved using either array CGH or ES. We have reviewed all syndromes that have appeared in "Smith's" with a focus on inheritance, heterogeneity, and year and method of etiologic discovery. Several themes emerge. Genetic heterogeneity and pleiotropy of genes are frequent. Several of the currently "unresolved" syndromes are clinically diverse such as Dubowitz syndrome. Multiple recurrent constellations of embryonic malformations, with VACTERL association as a paradigm, are increasingly likely to have a shared pathogenesis requiring further study.

Premature aging disorders: A clinical and genetic compendium

Progeroid disorders make up a heterogeneous group of very rare hereditary diseases characterized by clinical signs that often mimic physiological aging in a premature manner. Apart from Hutchinson-Gilford progeria syndrome, one of the best-investigated progeroid disorders, a wide spectrum of other premature aging phenotypes exist, which differ significantly in their clinical presentation and molecular pathogenesis. Next-generation sequencing (NGS)-based approaches have made it feasible to determine the molecular diagnosis in the early stages of a disease. Nevertheless, a broad clinical knowledge on these disorders and their associated symptoms is still fundamental for a comprehensive patient management and for the interpretation of variants of unknown significance from NGS data sets. This review provides a detailed overview on characteristic clinical features and underlying molecular genetics of well-known as well as only recently identified premature aging disorders and also highlights novel findings towards future therapeutic options.

New Diagnostic Approaches for Undiagnosed Rare Genetic Diseases

Accurate diagnosis is the cornerstone of medicine; it is essential for informed care and promoting patient and family well-being. However, families with a rare genetic disease (RGD) often spend more than five years on a diagnostic odyssey of specialist visits and invasive testing that is lengthy, costly, and often futile, as 50% of patients do not receive a molecular diagnosis. The current diagnostic paradigm is not well designed for RGDs, especially for patients who remain undiagnosed after the initial set of investigations, and thus requires an expansion of approaches in the clinic. Leveraging opportunities to participate in research programs that utilize new technologies to understand RGDs is an important path forward for patients seeking a diagnosis. Given recent advancements in such technologies and international initiatives, the prospect of identifying a molecular diagnosis for all patients with RGDs has never been so attainable, but achieving this goal will require global cooperation at an unprecedented scale.

Unsolved recognizable patterns of human malformation: Challenges and opportunities

Due to the efforts of the clinical and scientific communities and boosted by recent advances in genetic technologies, we now understand the molecular mechanisms underlying most of the frequent and recognizable human malformation syndromes. However, some well-established human malformation syndromes remain without a molecular diagnosis despite intensive investigation. This issue of Seminars mines the phenotypic entries in OMIM and estimates that of the documented 2,034 unsolved entries likely to represent a rare genetic disease, only 160 are well-established and possibly amenable to investigation. This issue also reviews well-characterized and extensively investigated human malformation syndromes and associations that remain unsolved, including the following: Dubowitz syndrome (MIM 223370%), Hallermann-Streiff syndrome (MIM 234100%), PHACE syndrome (MIM 606519), Oculocerebrocutaneous syndrome (MIM 164180), Aicardi syndrome (MIM 304050%), Gomez-Lopez-Hernandez syndrome and Rhombencephalosynapsis (MIM 601853%), VACTERL (MIM 192350%), and Nablus syndrome (MIM #608156). Possible explanations for their intractability to molecular diagnosis are explored, including genetic and phenotypic heterogeneity, mosaicism, epigenetics, gene-environment interactions, and other non-Mendelian contributions. Finally, this issue of Seminars presents a path forward for these unsolved rare conditions and suggests a renewed focus on solving amendable OMIM disorders. It is clear that the way forward will require new technologies, global cooperation, and data sharing; these will also be necessary to help reach the vision of the International Rare Diseases Research Consortium (IRDiRC), that is to enable all people living with a rare disease to receive an accurate diagnosis, care and available therapy within 1 year of coming to medical attention.