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AIM This article describes the craniofacial and dental features of an individual with Gordon syndrome. The dental management implications and considerations of treating patients with Gordon Syndrome and similar conditions resulting in limited mouth opening are discussed. METHODS A 14-year-old South African male was referred to the Dental Genetics Clinic with the main complaint of carious teeth. His craniofacial characteristics included low set and posteriorly rotated ears, down-slanted palpebral fissures, sloping shoulders, and a broad neck. A prognathic mandible and mild facial asymmetry were noted. He had a significant limitation of mouth opening (2 cm at incisors). Radiographic examination revealed multiple carious teeth, missing mandibular premolars, impacted maxillary premolars, taurodontism of the 44 and 34, and enlarged coronoid processes of the mandible. Dental extractions and restorations have been performed under local anaesthesia. CONCLUSION Gordon syndrome and similar conditions, may result in limited oral opening and impaired manual dexterity. The severity of limitation of mouth opening determines management. Dental management should focus on ensuring that the patient is able to maintain good oral hygiene by customising homecare for the individual and regular dental visits.

BackgroundThe timeous and accurate diagnosis of rare genetic disorders is critical, as it enables a better understanding of patient management, prognosis and more personalized treatment. A confirmed genetic diagnosis also enables accurate genetic counselling for affected individuals and their relatives by offering options for prenatal and cascade testing. In a resource-constrained environment such as the South African State healthcare system, the challenge is to design appropriate and cost-effective assays that will enable accurate genetic diagnostic services in patients of African ancestry across a broad disease spectrum. Next-generation sequencing (NGS) has transformed testing approaches for many Mendelian disorders, but this technology is still relatively expensive to implement. The paucity of baseline genetic data on African populations adds to the complexity of implementing an appropriate NGS-based service and interpretation of results.ResultIn the current study, the approach taken aimed at balancing NGS cost, efficiency, data quality as well as diagnostic utility of results. As a proof of concept, we describe a feasible diagnostic strategy for genetic disorders frequently seen in our genetics clinics (RASopathies, Cornelia de Lange syndrome, Treacher Collins syndrome, CHARGE syndrome and other phenotypically overlapping syndromes. The custom-designed targeted NGS gene panel enabled mutation screening for these disorders that range in incidence from 1 in 1000 to 1 in 100 000 newborns. Samples were batched during sequencing and analyzed selectively based on the clinical phenotype. This study had an overall diagnostic yield of 54.5%. ConclusionThe strategy employed is cost-effective as it allows batching of samples from patients with different diseases in a single run, an approach that can be utilized with rare and less frequently ordered molecular diagnostic tests. The subsequent selective analysis pipeline allowed for timeous reporting back of patients results. This is feasible and can be employed for the molecular diagnosis of a wide range of rare monogenic disorders in resource-constrained environment.

Objective\ud \ud Pathogenic variants in SCN3A , encoding the voltage‐gated sodium channel subunit Nav1.3, cause severe childhood‐onset epilepsy and malformation of cortical development. Here, we define the spectrum of clinical, genetic, and neuroimaging features of SCN3A ‐related neurodevelopmental disorder.\ud Methods\ud \ud Patients were ascertained via an international collaborative network. We compared sodium channels containing wild‐type vs. variant Nav1.3 subunits co‐expressed with β1 and β2 subunits using whole‐cell voltage clamp electrophysiological recordings in a heterologous mammalian system (HEK‐293 T cells).\ud Results\ud \ud Of 22 patients with pathogenic SCN3A variants, most had treatment‐resistant epilepsy beginning in the first year of life (16/21, 76%; median onset, 2 weeks), with severe or profound developmental delay (15/20; 75%). Many, but not all (15/19; 79%), exhibited malformations of cortical development. Pathogenic variants clustered in transmembrane segments 4–6 of domains II‐IV. Most pathogenic missense variants tested (10/11; 91%) displayed gain of channel function, with increased persistent current and/or a leftward shift in the voltage dependence of activation, and all variants associated with malformation of cortical development exhibited gain of channel function. One variant (p.Ile1468Arg) exhibited mixed effects, with gain and partial loss of function. Two variants demonstrated loss of channel function.\ud Interpretation\ud \ud Our study defines SCN3A‐ related neurodevelopmental disorder along a spectrum of severity, but typically including epilepsy and severe or profound developmental delay/intellectual disability. Malformations of cortical development are a characteristic feature of this unusual channelopathy syndrome, present in over 75% of affected individuals. Gain of function at the channel level in developing neurons is likely an important mechanism of disease pathogenesis.

Melnick-Needles syndrome (MNS; MIM 309350) is an X-linked skeletal dysplasia caused by mutations in FLNA. Females with the condition present with characteristic facial features, short stature, skeletal anomalies, including poorly modeled and sclerotic bones, and structural abnormalities such as cardiac and urological defects. Previously males were thought to present with either a mild phenotype compatible with life or a severe lethal presentation depending on the maternal phenotype. The discovery of a limited number of mutations in FLNA as the cause of the condition has clarified the molecular basis of the disorder, but only a very small number of severely affected males have been reported with MNS. Furthermore, no mildly affected males have been described with a molecular confirmation of the condition. In this report, we describe the clinical and molecular findings of a mildly affected mother with MNS and her severely affected son. They shared a well-documented disease-causing variant in FLNA, p.(Ala1188Thr), one of two highly recurrent mutations leading to the disorder. This is only the fourth report of a male with perinatal lethal MNS and a molecular confirmation; it is the first description of this specific mutation in a male.

Pena–Shokeir phenotype/fetal akinesia deformation sequence is characterized by the lack of fetal movement, fetal intrauterine growth restriction, craniofacial anomalies, arthrogryposis, polyhydramnios, and pulmonary hypoplasia. We report a case of Pena–Shokeir phenotype occurring in one fetus of a monoamniotic pair. We postulate that this resulted from hypoxia/anoxia due to early cord entanglement.

Schinzel-Giedion syndrome (SGS) is a rare developmental disorder characterized by multiple malformations, severe neurological alterations and increased risk of malignancy. SGS is caused by de novo germline mutations clustering to a 12bp hotspot in exon 4 of SETBP1. Mutations in this hotspot disrupt a degron, a signal for the regulation of protein degradation, and lead to the accumulation of SETBP1 protein. Overlapping SETBP1 hotspot mutations have been observed recurrently as somatic events in leukemia. We collected clinical information of 47 SGS patients ( including 26 novel cases) with germline SETBP1 mutations and of four individuals with a milder phenotype caused by de novo germline mutations adjacent to the SETBP1 hotspot. Different mutations within and around the SETBP1 hotspot have varying effects on SETBP1 stability and protein levels in vitro and in in silico modeling. Substitutions in SETBP1 residue I871 result in a weak increase in protein levels and mutations affecting this residue are significantly more frequent in SGS than in leukemia. On the other hand, substitutions in residue D868 lead to the largest increase in protein levels. Individuals with germline mutations affecting D868 have enhanced cell proliferation in vitro and higher incidence of cancer compared to patients with other germline SETBP1 mutations. Our findings substantiate that, despite their overlap, somatic SETBP1 mutations driving malignancy are more disruptive to the degron than germline SETBP1 mutations causing SGS. Additionally, this suggests that the functional threshold for the development of cancer driven by the disruption of the SETBP1 degron is higher than for the alteration in prenatal development in SGS. Drawing on previous studies of somatic SETBP1 mutations in leukemia, our results reveal a genotype-phenotype correlation in germline SETBP1 mutations spanning a molecular, cellular and clinical phenotype., Radboud University Medical Center; Max Planck Society; European Research Council (ERC); VIDI; Netherlands Organization for Scientific Research (NWO); Netherlands Organization for Scientific Research

Background. Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked recessive overgrowth syndrome manifesting primarily in boys and characterised by macrosomia, distinctive facial features and multiple congenital abnormalities. Although this rare condition is thought to be underdiagnosed, making a diagnosis is important as affected boys have a 7.5% risk of developing visceral tumours and surveillance is warranted. Mutations in GPC3 are found in up to 70% of boys affected with SGBS. Objectives. A clinical and molecular investigation of two boys with SGBS, probands B and S, and their mothers. Documentation of the clinical phenotype could assist with diagnosis in affected boys and will lead to early initiation of tumour surveillance. Methods. Hospital folders were reviewed and clinical consultations arranged for both probands and their mothers. Molecular investigations initially searched for whole-exon deletions in GPC3 followed by gene sequencing. Results. The clinical phenotype of both probands was consistent with that previously reported in the literature. The main features pointing towards the diagnosis were macrosomia, coarse facial features and macroglossia with a midline groove in the tongue. Proband B developed a Wilms tumour. He was found to have a novel mutation causing a premature stop codon. Conclusions. This research represents the first published report of SGBS in South Africa. Early recognition and confirmation of this condition is important in order to institute tumour surveillance and assist families with accurate recurrence risks.

This editorial examines a number of vitally important ethical, legal and scientific concerns that have to be addressed to ensure proper and ethical implementation of direct-to-consumer whole-exome sequencing in South Africa. Individuals taking part in this endeavour must be fully informed of the positive and negative sequelae.