FGD1-related Aarskog-Scott syndrome: Identification of four novel variations and a literature review of clinical and molecular aspects.

Patients with Aarskog-Scott syndrome (AAS) have short stature, facial anomalies, skeletal deformities, and genitourinary malformations. FYVE, RhoGEF, and PH domain-containing 1 (FGD1) is the only known causative gene of AAS. However, the diagnosis of AAS remains difficult, and specific treatments are still absent. Patients suspected with AAS were recruited, and clinical information was collected. Genetic testing and functional analysis were carried out for the diagnosis. By literature review, we summarized the clinical and genetic characteristics of FGD1-related AAS and analyzed the genotype-phenotype correlation. Five patients were recruited, and four novel FGD1 variants were identified. The diagnosis of AAS was confirmed by genetic analysis and functional study. Three patients treated with growth hormone showed improved heights during the follow-up period. By literature review, clinical features of AAS patients with FGD1 variants were summarized. Regarding FGD1 variations, substitutions were the most common form, and among them, missense variants were the most frequent. Moreover, we found patients with drastic variants showed higher incidences of foot and genitourinary malformations. Missense variants in DH domain were related to a lower incidence of cryptorchidism.   Conclusion: We reported four novel pathogenic FGD1 variations in AAS patients and confirmed the efficacy and safety of growth hormone treatment in FGD1-related AAS patients with growth hormone deficiency. Additionally, our literature review suggested the crucial role of DH domain in FGD1 function. What is Known: • Aarskog-Scott syndrome is a rare genetic disease, and the only known cause is the variant in FGD1 gene. The typical clinical manifestations of AAS include facial, skeletal, and urogenital deformities and short stature. What is New: • We reported four novel FGD1 variants and reported the treatment of growth hormone in FGD1-related AAS patients. Our genotype-phenotype correlation analysis suggested the crucial role of DH domain in FGD1 function.

Cutaneous squamous cell carcinoma in an autosomal-recessive Adams-Oliver syndrome patient with a novel frameshift pathogenic variant in the EOGT gene.

Aplasia cutis congenita (ACC) of the scalp and terminal transverse limb defects (TTLD) are the characteristic findings of Adams-Oliver syndrome (AOS). The variable clinical spectrum further includes cardiac, neurologic, renal, and ophthalmological findings. Associated genes in AOS are in the Notch and the CDC42/Rac1 signaling pathways. Both autosomal-dominant and autosomal-recessive inheritances have been reported, the latter with pathogenic variants in DOCK6 or EOGT. The EOGT-associated recessive type of AOS has been postulated to present a more favorable prognosis. We here report a 12-year-old girl from a refugee family of Iraq with consanguineous parents. She was born with a severe phenotype of AOS presenting a large ACC of the scalp with an underlying skull defect, which was often infected and inflamed. Afterward, additional ulceration developed. Furthermore, the girl showed microcephaly, TTLD on both hands and feet, and neurological findings: spastic paresis, epilepsy and suspicion of intellectual deficit. Molecular genetic analysis (next-generation sequencing) revealed a novel frameshift mutation in the EOGT gene in Exon 13 in homozygous constellation: c.1013dupA p.(Asn338Lysfs*24). A biopsy within an ulceration at the scalp ACC showed a cutaneous squamous cell carcinoma (cSCC) with local invasive growth into the dura, the meninges, and the cortex. Treatment including surgical resection and focal irradiation was not curative and the girl deceased 6 months after initial diagnosis. This report on a patient with AOS and an autosomal-recessive EOGT gene variant dying of a local aggressive cSCC at an ACC lesion shows that close monitoring of ACC is essential.

A novel DLL4 mutation in Adams-Oliver syndrome with absence of the right pulmonary artery in newborn.

Adams-Oliver syndrome (AOS), a rare inherited disorder, is characterized by scalp and terminal limb defects. Several genes associated with Notch pathway mutations have led to AOS. Here, we report a Thai male newborn presenting with aplasia cutis congenita and absence of a right pulmonary artery, which is suggestive of AOS. This was confirmed by the identification of a novel missense mutation in DLL4, a heterozygous one base pair change at nucleotide 82 (c.82G>C, p.Gly28Arg), which is in N-terminal domain. This is the first DLL4-related AOS case with arterial defect.

Two AOS genes attributed to familial exudative vitreoretinopathy with microcephaly: Two case reports.

RATIONALE: Familial exudative vitreoretinopathy (FEVR) is an inherited disorder, which is mostly reported to be associated with the mutation of genes involved in the Wnt signaling pathway related to ß-catenin. To the best of our knowledge, the involvement of Adams-Oliver syndrome (AOS) genes in FEVR patients have not been reported before. PATIENT CONCERNS: Two patients with FEVR presented with microcephaly. One of them showed slight scarring of the scalp vertex which is a typical manifestation of AOS. The whole exon sequencing confirmed the diagnosis of AOS with 2 AOS-gene mutations at DOCK6 and ARHGAP31. Further clinical examination revealed that their parents with the same mutations showed FEVR-like vascular anomalies. DIAGNOSIS: Both patients were diagnosed with AOS through whole exon sequencing, and they presented with some FEVR-like retinopathy including retinal detachment. INTERVENTIONS: Both patients received vitrectomy for tractional retinal detachment with proliferative vitreoretinopathy. During the follow-up, 1 patient received additional laser photocoagulation for tractional retinal detachment. OUTCOMES: The 2 patients remained stable in the latest follow up after the treatment. LESSONS: Microcephaly could be associated with some form of retinopathy. We proposed that mutation of DOCK6 and ARHGAP31 genes could be the possible cause of FEVR associated with microcephaly. Our study suggested that these genes may be candidate genes of FEVR.

Genotype-Phenotype Correlation of Tracheal Cartilaginous Sleeves and Fgfr2 Mutations in Mice.

OBJECTIVES: To characterize tracheal cartilage morphology in mouse models of fibroblast growth factor receptor (Fgfr2)-related craniosynostosis syndromes. To establish relationships between specific Fgfr2 mutations and tracheal cartilaginous sleeve (TCS) phenotypes in these mouse models. METHODS: Postnatal day 0 knock-in mouse lines with disease-specific genetic variations in the Fgfr2 gene (Fgfr2C342Y/C342Y , Fgfr2C342Y/+ , Fgfr2+/Y394C , Fgfr2+/S252W , and Fgfr2+/P253R ) as well as line-specific controls were utilized. Tracheal cartilage morphology as measured by gross analyses, microcomputed tomography (µCT), and histopathology were compared using Chi-squared and single-factor analysis of variance statistical tests. RESULTS: A greater proportion of rings per trachea were abnormal in Fgfr2C342Y/+ tracheas (63%) than Fgfr2+/S252W (17%), Fgfr2+/P253R (17%), Fgfr2+/Y394C (12%), and controls (10%) (P < .001 for each vs. Fgfr2C342Y/+ ). TCS segments were found only in Fgfr2C342Y/C342Y (100%) and Fgfr2C342Y/+ (72%) tracheas. Cricoid and first-tracheal ring fusion was noted in all Fgfr2C342Y/C342Y and 94% of Fgfr2C342Y/+ samples. The Fgfr2C342Y/C342Y and Fgfr2C342Y/+ groups were found to have greater areas and volumes of cartilage than other lines on gross analysis and µCT. Histologic analyses confirmed TCS among the Fgfr2C342Y/C342Y and Fgfr2C342Y/+ groups, without appreciable differences in cartilage morphology, cell size, or density; no histologic differences were observed among other Fgfr2 lines compared to controls. CONCLUSION: This study found TCS phenotypes only in the Fgfr2C342Y mouse lines. These lines also had increased tracheal cartilage compared to other mutant lines and controls. These data support further study of the Fgfr2 mouse lines and the investigation of other Fgfr2 variants to better understand their role in tracheal development and TCS formation. LEVEL OF EVIDENCE: NA Laryngoscope, 131:E1349-E1356, 2021.

A novel variant in DOCK6 gene associated with Adams-Oliver syndrome type 2.

BACKGROUND: Adams-Oliver syndrome (AOS) is a rare, inherited multi-systemic malformation syndrome characterized by a combination of aplasia cutis congenita and transverse terminal limb defects along with variable involvement of the central nervous system, eyes, and cardiovascular system. AOS can be inherited as both autosomal-dominant and recessive traits. Pathogenic variants in the DOCK6, ARHGAP31, EOGT, RBPJ, DLL4, and NOTCH1 genes have been associated with AOS. PURPOSE: To report a novel homozygous variant in the DOCK6 gene associated with Adams-Oliver syndrome type 2. MATERIALS AND METHODS: Case report. RESULTS: We report a case of a 4-month-old male who presented with microcephaly, global developmental delay, truncal hypotonia, and limb reduction defects. Ophthalmic examination revealed bilateral nystagmus and retinal detachment with mild cataractous changes in addition to retrolental plaque in the left eye. Next generation sequencing analysis identified a novel homozygous frameshift likely pathogenic variant (c.1269_1285dup (p.Arg429Glnfs*32)) in the DOCK6 gene. The constellation of the clinical findings and the genetic mutation were consistent with a diagnosis of AOS type 2. CONCLUSION: The discovery of this new likely pathogenic variant enriches the genotypic spectrum of DOCK6 gene and contributes to genetic diagnosis and counseling of families with AOS. Neurologic and ocular findings appear to be consistent with AOS type 2 for which multidisciplinary clinical evaluation is crucial.

Novel In-Frame Deletion Mutation in NOTCH1 in a Chinese Sporadic Case of Adams-Oliver Syndrome.

Adams-Oliver syndrome (AOS) is a rare hereditary disorder characterized by aplasia cutis congenita (ACC) and terminal transverse limb defects. The etiology of AOS has remained largely unknown, although mutations in the notch receptor 1 (NOTCH1) gene are most common genetic alteration associated with this disease. In this study, we aimed to identify the case of a 6-year-old boy, who presented with large ACC of the scalp and aortic valve stenosis, suggesting the possibility of AOS. Whole-exome sequencing identified a novel, de novo, in-frame deletion in the NOTCH1 gene (NOTCH1 c.1292_1294del, p.Asn431del) in the patient. The p.Asn431del variant was evaluated by several in silico analyses, which predicted that the mutant was likely to be pathogenic. In addition, molecular modeling with the PyMOL Molecular Graphics System suggested that the NOTCH1-N431del destabilizes calcium ion chelation, leading to decreased receptor-ligand binding efficiency. Quantitative reverse transcription PCR showed further significant downregulation of the Notch target genes, hes-related family bHLH transcription factor with YRPW motif 1 (HEY1) and hes family bHLH transcription factor 1 (HES1), suggesting that this mutation causes disease through dysregulation of the Notch signaling pathway. Our study provides evidence that the NOTCH1-N431del mutation is responsible for this case of AOS. To our knowledge, this is the first report of a patient with AOS caused by NOTCH1 mutation in Asia, and this information will be useful for providing the family with genetic counseling that can help to guide their future plans.

Expanding the phenotype in Adams-Oliver syndrome correlating with the genotype.

RATIONALE: Adams-Oliver syndrome (AOS) is a genetic disorder characterized by the association of aplasia cutis congenita (ACC), terminal transverse limb defect (TTLD), congenital cardiac malformation (CCM), and minor features, such as cutaneous, neurological, and hepatic abnormalities (HAs). The aim of the study is to emphasize phenotype-genotype correlations in AOS. METHODS: We studied 29 AOS patients. We recorded retrospectively detailed phenotype data, including clinical examination, biological analyses, and imaging. The molecular analysis was performed through whole exome sequencing (WES). RESULTS: Twenty-nine patients (100%) presented with ACC, the principal inclusion criteria in the study. Seventeen of twenty-one (81%) had cutis marmorata telangiectasia congenita, 16/26 (62%) had TTLD, 14/23 (61%) had CCM, 7/20 (35%) had HAs, and 9/27 (33%) had neurological findings. WES was performed in 25 patients. Fourteen of twenty-five (56%) had alterations in the genes already described in AOS. CCM and HAs are particularly associated with the NOTCH1 genotype. TTLD is present in patients with DOCK6 and EOGT alterations. Neurological findings of variable degree were associated sometimes with DOCK6 and NOTCH1 rarely with EOGT. CONCLUSION: AOS is characterized by a clinical and molecular variability. It appears that degrees of genotype-phenotype correlations exist for patients with identified pathogenic mutations, underlining the need to undertake a systematic but adjusted multidisciplinary assessment.

Adams-Oliver syndrome caused by mutations of the EOGT gene.

Adams-Oliver syndrome (AOS) is a rare congenital disease characterized by aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). It shows significant genetic heterogeneity and can be transmitted by autosomal dominant or recessive inheritance. Recessive inheritance is associated with mutations of DOCK6 or EOGT; however, only few cases have been published so far. We present two families with EOGT-associated AOS. Due to pseudodominance in one family, the recognition of the recessive inheritance pattern was difficult. We identified two novel AOS-causing mutations (c.404G>A/p.Cys135Tyr and c.311+1G>T). The phenotype in the presented families was dominated by large ACC, whereas TTLD were mostly subtle or even absent and no major malformations occured. Our observations along with the previously published cases indicate that the two types of recessive AOS (EOGT- vs. DOCK6-associated) differ significanty regarding the frequency of neurologic or ocular deficits.

Scrotal elephantiasis associated with follicular occlusion triad: A case report and literature review.

RATIONALE: Follicular occlusion triad (FOT) is an autosomal recessive inherited disease and no more than 3 variants of the triad have been reported. We give a report in which scrotal elephantiasis is a variant of FOT and further perform a literature review. PATIENT CONCERNS: A 41-year-old man came to us because of a large scrotal cyst and generalized skin lesions that had occurred over the past 10 years. The generalized skin lesions consisted of hidradenitis suppurativa on the perineum and back, acne conglobata in the armpit, and dissecting cellulitis of the scalp. He took antibiotics for a long time but achieved poor effect. Furthermore, he told his father and elder brother also manifested such skin lesions. DIAGNOSES: Magnetic resonance showed a mass in the left scrotum with clear boundaries. A routine blood test showed a high leukocyte level of 12 × 10/L and a hemoglobin content of 78 g/L. C-reactive-protein increased. Series of autoimmune antibody tests were negative. The postoperative pathologic findings showed that the mass was an epidermoid cyst, and hematoxylin and eosin staining showed hyperkeratosis of the skin as well as inflammatory and edematous changes. A diagnosis of a variant of FOT was made. INTERVENTIONS: We removed skin abscesses and lesioned the inner part with hydrogen peroxide. Then we performed an excision of the scrotal lesion. OUTCOME: The patient recovered well and had no evidence of recurrence at a 16-month follow-up. LESSONS: We reported a case in which scrotal elephantiasis was a variant of FOT and surgical intervention played an important role in secondary urologic diseases.

[Analysis of DOCK6 gene mutation in a child affected with Adams-Oliver syndrome type 2].

OBJECTIVE: To detect pathogenic mutation of DOCK6 gene in a patient with convulsive seizure and refractory epilepsy. METHODS: CytoScan HD-Array and next generation sequencing were used to detect the potential mutation in the patient. RESULTS: The proband has carried compound heterozygous mutations of c.188C>T (p.Arg63Gln) and c.5374C>T (p.Glu1792Lys) of the DOCK6 gene, which were respectively inherited from his mother and father. Neither mutation was reported previously. Bioinformatic analysis indicated that the two amino acids are highly conserved. Based on the ACMG guidelines, the c.188C>T mutation was predicted to be likely pathogenic, while the c.5374C>T mutation was of uncertain significance. CONCLUSION: The compound heterozygous mutations of c.188C>T (p.Arg63Gln) and c.5374C>T (p.Glu1792Lys) of the DOCK6 gene probably underlie the disease in this patient.

Novel compound heterozygous mutations of the DOCK6 gene in a familial case of Adams-Oliver syndrome 2.

INTRODUCTION: Adams-Oliver syndrome (AOS) is a rare developmental disorder characterized by the combination of aplasia cutis congenita of the scalp vertex and terminal transverse limb defects. DOCK6 (Dedicator of cytokinesis 6) is one of the six identified AOS genes. METHODS: We performed targeted next-generation sequencing (NGS) of a child with an AOS phenotype. Sanger DNA sequencing further validated her lineal consanguinity. To explore the pathological features of the mutation, a minigene assay was used to investigate the effects of the mutation on splicing. RESULTS: Two compound heterozygous DOCK6 mutations (c.4106+2T>C and c.3063 C>G (p.Y1021*)) were identified in this family, and both mutations have not been reported previously. Sanger DNA sequencing indicated that the mutations were inherited maternally and paternally, respectively. The results of the minigene assay showed that the c.4106+2T>C mutation resulted in aberrant splicing and caused a four-nucleotide insertion in the transcript and a premature stop codon. CONCLUSIONS: Our findings expanded the number of reported cases of this rare disease and the mutation spectrum of DOCK6 mutations, which can serve as the basis for prenatal diagnosis and genetic counseling.

Mechanism of cell-intrinsic adaptation to Adams-Oliver Syndrome gene DOCK6 disruption highlights ubiquitin-like modifier ISG15 as a regulator of RHO GTPases.

DOCK6 is a RAC1/CDC42 guanine nucleotide exchange factor, however, little is known about its function and sub-cellular localization. DOCK6 regulates the balance between RAC1 and RHOA activity during cell adhesion and is important for CDC42-dependent mitotic chromosome alignment. Surprisingly, a cell intrinsic adaptation mechanism compensates for errors in these DOCK6 functions that arise as a consequence of prolonged DOCK6 depletion or complete removal in DOCK6 knockout cells. Down-regulation of the ubiquitin-like modifier ISG15 accounts for this adaptation. Strikingly, although most other DOCK family proteins are deployed on the plasma membrane, here we show that DOCK6 localizes to the endoplasmic reticulum (ER) in dependence of its DHR-1 domain. ER localization of DOCK6 opens up new insights into its functions.

Overlapping but distinct roles for NOTCH receptors in human cardiovascular disease.

The NOTCH signalling pathway is an essential pathway, involved in many cellular processes, including cell fate decision, cell proliferation, and cell death and important in the development of most organs. Mutations in genes encoding components of the NOTCH signalling pathway lead to a spectrum of congenital disorders. Over the past decades, mutations in human NOTCH signalling genes have been identified in several diseases with cardiovascular involvement. NOTCH1 mutations have been described in bicuspid aortic valve disease, left-sided congenital heart disease, and Adams-Oliver syndrome. NOTCH2 mutations lead to the development of Alagille syndrome, while mutations in NOTCH3 cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. To date, mutations in NOTCH4 have not been associated with cardiovascular disease. This review focuses on the mutations described in NOTCH1, NOTCH2, and NOTCH3 and their associated cardiovascular phenotypes.

Intracranial Calcifications in Young Children.

Intracranial calcifications in young infants, while suggesting intrauterine infections, can also be due to numerous other conditions, including rare genetic disorders. We describe 2 children in whom the presence and pattern of intracranial calcifications led to the diagnosis of uncommon genetic disorders, Adams-Oliver syndrome and Aicardi-Goutieres syndrome. Differentiating genetic conditions from intrauterine infections or other causes of intracranial calcifications enables practitioners to provide accurate counseling regarding prognosis and recurrence risk.

Elucidating the genetic architecture of Adams-Oliver syndrome in a large European cohort.

Adams-Oliver syndrome (AOS) is a rare developmental disorder, characterized by scalp aplasia cutis congenita (ACC) and transverse terminal limb defects (TTLD). Autosomal dominant forms of AOS are linked to mutations in ARHGAP31, DLL4, NOTCH1 or RBPJ, while DOCK6 and EOGT underlie autosomal recessive inheritance. Data on the frequency and distribution of mutations in large cohorts are currently limited. The purpose of this study was therefore to comprehensively examine the genetic architecture of AOS in an extensive cohort. Molecular diagnostic screening of 194 AOS/ACC/TTLD probands/families was conducted using next-generation and/or capillary sequencing analyses. In total, we identified 63 (likely) pathogenic mutations, comprising 56 distinct and 22 novel mutations, providing a molecular diagnosis in 30% of patients. Taken together with previous reports, these findings bring the total number of reported disease variants to 63, with a diagnostic yield of 36% in familial cases. NOTCH1 is the major contributor, underlying 10% of AOS/ACC/TTLD cases, with DLL4 (6%), DOCK6 (6%), ARHGAP31 (3%), EOGT (3%), and RBPJ (2%) representing additional causality in this cohort. We confirm the relevance of genetic screening across the AOS/ACC/TTLD spectrum, highlighting preliminary but important genotype-phenotype correlations. This cohort offers potential for further gene identification to address missing heritability.

Epileptic Encephalopathy in Adams-Oliver Syndrome Associated to a New DOCK6 Mutation: A Peculiar Behavioral Phenotype.

Adams-Oliver syndrome (AOS) is characterized by a combination of congenital scalp defects (aplasia cutis congenita) and terminal transverse limb malformations of variable severity. When neurological findings are present, patients are reported as AOS variants. We describe a child with compound heterozygosity of the DOCK6 gene, aplasia cutis, terminal transverse limb defects, cardiovascular impairment, intellectual disability, and brain malformations with intracranial calcifications. He suffers from a severe refractory epileptic encephalopathy characterized by polymorphic seizures with prolonged periods of electroencephalogram (EEG), continuous epileptiform activity related to clinical inactivity, and closure of eyes with an "ON-OFF" behavior.

Adams-Oliver Syndrome Type 2 in Association with Compound Heterozygous DOCK6 Mutations.

Adams-Oliver syndrome (AOS) is a multiple congenital anomaly syndrome characterized by aplasia cutis congenita (ACC) and transverse terminal limb defects (TTLDs). We present a case of type 2 autosomal recessive AOS associated with heterozygous mutations in the dedicator of cytokinesis 6 (DOCK6) gene, with characteristic findings of ACC, TTLD, intracerebral periventricular calcifications, and polymicrogyria.