Microcephalic Osteodysplastic Primordial Dwarfism, Type II: a Clinical Review

Imaging Review of Pediatric Monogenic CNS Vasculopathy with Genetic Correlation

Monogenic cerebral vasculopathy is a rare but progressively recognizable cause of pediatric cerebral vasculopathy manifesting as early as fetal life. These monogenic cerebral vasculopathies can be silent or manifest variably as fetal or neonatal distress, neurologic deficit, developmental delay, cerebral palsy, seizures, or stroke. The radiologic findings can be nonspecific, but the presence of disease-specific cerebral and extracerebral imaging features can point to a diagnosis and guide genetic testing, allowing targeted treatment. The authors review the existing literature describing the frequently encountered and rare monogenic cerebral vascular disorders affecting young patients and describe the relevant pathogenesis, with an attempt to categorize them based on the defective step in vascular homeostasis and/or signaling pathways and characteristic cerebrovascular imaging findings. The authors also highlight the role of imaging and a dedicated imaging protocol in identification of distinct cerebral and extracerebral findings crucial in the diagnostic algorithm and selection of genetic testing. Early and precise recognition of these entities allows timely intervention, preventing or delaying complications and thereby improving quality of life. It is also imperative to identify the specific pathogenic variant and pattern of inheritance for satisfactory genetic counseling and care of at-risk family members. Last, the authors present an image-based approach to these young-onset monogenic cerebral vasculopathies that is guided by the size and predominant radiologic characteristics of the affected vessel with reasonable overlap. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Small size, big problems: insights and difficulties in prenatal diagnosis of fetal microcephaly

Microcephaly is a sign, not a diagnosis. Its incidence varies widely due to the differences in the definition and the population being studied. It is strongly related to neurodevelopmental disorders. Differences in definitions and measurement techniques between fetuses and newborns pose a great challenge for the diagnosis and prognostication of fetal microcephaly. A false positive diagnosis can result (in countries where it is legal) in erroneous termination of pregnancy, where a false negative diagnosis might lead to the birth of a microcephalic newborn. Microcephaly in growth restricted fetuses deserves special attention and separate evaluation as it is an important prognostic factor, and not necessarily part of the general growth retardation. Several genetic syndromes incorporating microcephaly and intrauterine growth retardation (IUGR) are discussed. Deceleration of the head circumference (HC) growth rate even when the HC is still within normal limits might be the only clue for developing microcephaly and should be considered during fetal head growth follow up. Combining additional parameters such as a positive family history, associated anomalies, and new measurement parameters can improve prediction in about 50% of cases, and thus should be part of the prenatal workup. Advances in imaging modalities and in prenatal genetic investigation along with the emergence of new growth charts can also improve diagnostic accuracy. In this article, we review the different definitions and etiologies of fetal microcephaly, discuss difficulties in diagnosis, investigate the reasons for the low yield of prenatal diagnosis, and provide improvement suggestions. Finally, we suggest an updated algorithm that will aid in the diagnosis and management of fetal microcephaly.

Mutational analysis of consanguineous families and their targeted therapy against dwarfism

Dwarfism is a medical term used to describe individuals with a height-vertex measurement that falls below two standard deviations (-2SD) or the third percentile for their gender and age. Normal development of growth is a complicated dynamic procedure that depends upon the coordination of different aspects involving diet, genetics, and biological aspects like hormones in equilibrium. Any severe or acute pathologic procedure may disturb the individual's normal rate of growth. In this research, we examined four (A-D) Pakistani consanguineous families that exhibited syndromic dwarfism, which was inherited in an autosomal recessive pattern. The genomic DNA of each family member was extracted by using phenol-chloroform and Kit methods. Whole Exome Sequencing (WES) of affected family members (IV-11, III-5, IV-4 and III-13) from each group was performed at the Department of Medical Genetics, University of Antwerp, Belgium. After filtering the exome data, the mutations in PPM1F, FGFR3, ERCC2, and PCNT genes were determined by Sanger sequencing of each gene by using specific primers. Afterward, FGFR3 was found to be a suitable drug target among all the mutations to treat achondroplasia also known as disproportionate dwarfism. BioSolveIT softwares were used to discover the lead active inhibitory molecule against FGFR3. This research will not only provide short knowledge to the concerned pediatricians, researchers, and family physicians for the preliminary assessment and management of the disorder but also provide a lead inhibitor for the treatment of disproportionate dwarfism.Communicated by Ramaswamy H. Sarma.

Pericentrin deficiency in smooth muscle cells augments atherosclerosis through HSF1-driven cholesterol biosynthesis and PERK activation

Microcephalic osteodysplastic primordial dwarfism type II (MOPDII) is caused by biallelic loss-of-function variants in pericentrin (PCNT), and premature coronary artery disease (CAD) is a complication of the syndrome. Histopathology of coronary arteries from patients with MOPDII who died of CAD in their 20s showed extensive atherosclerosis. Hyperlipidemic mice with smooth muscle cell-specific (SMC-specific) Pcnt deficiency (PcntSMC-/-) exhibited significantly greater atherosclerotic plaque burden compared with similarly treated littermate controls despite similar serum lipid levels. Loss of PCNT in SMCs induced activation of heat shock factor 1 (HSF1) and consequently upregulated the expression and activity of HMG-CoA reductase (HMGCR), the rate-limiting enzyme in cholesterol biosynthesis. The increased cholesterol biosynthesis in PcntSMC-/- SMCs augmented PERK signaling and phenotypic modulation compared with control SMCs. Treatment with the HMGCR inhibitor, pravastatin, blocked the augmented SMC modulation and reduced plaque burden in hyperlipidemic PcntSMC-/- mice to that of control mice. These data support the notion that Pcnt deficiency activates cellular stress to increase SMC modulation and plaque burden, and targeting this pathway with statins in patients with MOPDII has the potential to reduce CAD in these individuals. The molecular mechanism uncovered further emphasizes SMC cytosolic stress and HSF1 activation as a pathway driving atherosclerotic plaque formation independently of cholesterol levels.

Whole-Exome and Transcriptome Sequencing Expands the Genotype of Majewski Osteodysplastic Primordial Dwarfism Type II

Microcephalic Osteodysplastic Primordial Dwarfism type II (MOPDII) represents the most common form of primordial dwarfism. MOPD clinical features include severe prenatal and postnatal growth retardation, postnatal severe microcephaly, hypotonia, and an increased risk for cerebrovascular disease and insulin resistance. Autosomal recessive biallelic loss-of-function genomic variants in the centrosomal pericentrin (PCNT) gene on chromosome 21q22 cause MOPDII. Over the past decade, exome sequencing (ES) and massive RNA sequencing have been effectively employed for both the discovery of novel disease genes and to expand the genotypes of well-known diseases. In this paper we report the results both the RNA sequencing and ES of three patients affected by MOPDII with the aim of exploring whether differentially expressed genes and previously uncharacterized gene variants, in addition to PCNT pathogenic variants, could be associated with the complex phenotype of this disease. We discovered a downregulation of key factors involved in growth, such as IGF1R, IGF2R, and RAF1, in all three investigated patients. Moreover, ES identified a shortlist of genes associated with deleterious, rare variants in MOPDII patients. Our results suggest that Next Generation Sequencing (NGS) technologies can be successfully applied for the molecular characterization of the complex genotypic background of MOPDII.

Case Report: short stature, kidney anomalies, and cerebral aneurysms in a novel homozygous mutation in the PCNT gene associated with microcephalic osteodysplastic primordial dwarfism type II

We report the case of a boy (aged 3 years and 7 months) with severe growth failure (length: -9.53 SDS; weight: -9.36 SDS), microcephaly, intellectual disability, distinctive craniofacial features, multiple skeletal anomalies, micropenis, cryptorchidism, generalized hypotonia, and tendon retraction. Abdominal US showed bilateral increased echogenicity of the kidneys, with poor corticomedullary differentiation, and a slightly enlarged liver with diffuse irregular echotexture. Initial MRI of the brain, performed at presentation, showed areas of gliosis with encephalomalacia and diffused hypo/delayed myelination, and a thinned appearance of the middle and anterior cerebral arteries. Genetic analysis evidenced a novel homozygous pathogenic variant of the pericentrin (PCNT) gene. PCNT is a structural protein expressed in the centrosome that plays a role in anchoring of protein complexes, regulation of the mitotic cycle, and cell proliferation. Loss-of-function variants of this gene are responsible for microcephalic osteodysplastic primordial dwarfism type II (MOPDII), a rare inherited autosomal recessive disorder. The boy died at 8 years of age as a result of an intracranial hemorrhage due to a cerebral aneurism associated with the Moyamoya malformation. In confirmation of previously published results, intracranial anomalies and kidney findings were evidenced very early in life. For this reason, we suggest including MRI of the brain with angiography as soon as possible after diagnosis in follow-up of MODPII, in order to identify and prevent complications related to vascular anomalies and multiorgan failure.

Role of Medical IoT-Based Bone Age Determination in the Diagnosis and Clinical Treatment of Dwarfism Disease Monitoring

Currently, the prevalence of dwarfism in children in China is about 3%, which is a very large percentage compared with the large population base. With the increase of influencing factors, the prevalence of dwarfism is on the increase. However, there is a lack of awareness of dwarfism among parents and a lack of in-depth analysis of the causes of dwarfism and a low level of treatment among doctors. Early expert system knowledge base relies on manual editing, which is a traditional, semi-intelligent auxiliary diagnostic system, and is unable to perform disease diagnosis and clinical treatment monitoring well. Many studies have turned to the combination of IoT for bone age determination and its role in the diagnosis and monitoring of clinical treatment of dwarfism. In this study, 15 children with short stature who underwent health checkups at a hospital were enrolled in the study, and a G-P spectrum method was used to determine the bone age of all the enrolled subjects, and the results obtained in the process of bone age determination were systematically analyzed. The results showed that the bone age measurement technique has sufficient reference value for evaluating the quality and diagnosing diseases, and the research and development of this technique is of great significance for the development of modern clinical medicine.

Novel frameshift variant in the PCNT gene associated with Microcephalic Osteodysplastic Primordial Dwarfism (MOPD) Type II and small kidneys

Background

Microcephalic Osteodysplastic Primordial Dwarfism (MOPD) Type II is an autosomal recessive condition encompassing a heterogeneous group of disorders characterized by symmetrical growth retardation leading to dwarfism, microcephaly, and a range of multiple medical complications including neurovascular diseases. Biallelic pathogenic variants in the pericentrin gene (PCNT) have been implicated in its pathogenesis.

Case presentation

We performed whole-exome sequencing to ascertain the diagnosis of a 2 year and 6 months old boy who presented with severe failure to thrive, microcephaly, and facial gestalt suggestive of MOPD Type II which included features such as retrognathia, small ears, prominent nasal root with a large nose, microdontia, sparse scalp hair, bilateral fifth finger clinodactyly. He had a small ostium secundum atrial septal defect and bilaterally small kidneys. Microcephalic Osteodysplastic Primordial Dwarfism (MOPD) Type II was confirmed based on a pathogenic compound heterozygous frameshift variant in the PCNT gene c.5059_5060delAA | p. Asn1687fs (novel variant) and c.9535dup (p. Val3179fs). His parents were found to be heterozygous carriers for the variants.

Conclusion

We report a novel frameshift variant in the PCNT gene and a previously unreported phenotype for Microcephalic Osteodysplastic Primordial Dwarfism (MOPD) Type II.

Microcephalic Osteodysplastic Primordial Dwarfism Type II With Associated Glucose-6-Phosphate Dehydrogenase Deficiency in a Saudi Girl

Microcephalic primordial dwarfism is a group of disorders that result in growth restriction and multiple morbidities. The condition is subdivided into three categories, with microcephalic osteodysplastic primordial dwarfism type II (MOPDII) being the most prevalent. Globally, only a few cases have been reported, with only available information about these disorders described in the literature. In this case report, we present the clinical findings seen in an infant with MOPDII in Saudi Arabia with associated glucose-6-phosphate dehydrogenase deficiency hemolytic anemia.

Diagnostic difficulties and possibilities of NF1-like syndromes in childhood

BACKGROUND

Neurofibromatosis type 1 (NF1), which is caused by heterozygous inactivating pathogenic variants in the NF1, has poor phenotypic expressivity in the early years of life and there are numerous conditions, including many other tumor predisposition syndromes, that can mimic its appearance. These are collectively termed NF1-like syndromes and are also connected by their genetic background. Therefore, the NF1's clinical diagnostic efficiency in childhood could be difficult and commonly should be completed with genetic testing.

METHODS

To estimate the number of syndromes/conditions that could mimic NF1, we compiled them through an extensive search of the scientific literature. To test the utility of NF1's National Institutes of Health (NIH) clinical diagnostic criteria, which have been in use for a long time, we analyzed the data of a 40-member pediatric cohort with symptoms of the NF1-like syndromes' overlapping phenotype and performed NF1 genetic test, and established the average age when diagnostic suspicion arises. To facilitate timely identification, we compiled strongly suggestive phenotypic features and anamnestic data.

RESULTS

In our cohort the utility of NF1's clinical diagnostic criteria were very limited (sensitivity: 80%, specificity: 30%). Only 53% of children with clinically diagnosed NF1 had a detectable NF1 pathogenic variation, whereas 40% of patients without fulfilled clinical criteria tested positive. The average age at first genetic counseling was 9 years, and 40% of children were referred after at least one tumor had already been diagnosed. These results highlight the need to improve NF1-like syndromes' diagnostic efficiency in childhood. We collected the most extensive spectrum of NF1-like syndromes to help the physicians in differential diagnosis. We recommend the detailed, non-invasive clinical evaluation of patients before referring them to a clinical geneticist.

CONCLUSIONS

Early diagnosis of NF1-like syndromes can help to prevent severe complications by appropriate monitoring and management. We propose a potential screening, diagnostic and management strategy based on our findings and recent scientific knowledge.

Multifaceted roles of centrosomes in development, health, and disease

The centrosome is a membrane-less organelle consisting of a pair of barrel-shaped centrioles and pericentriolar material and functions as the major microtubule-organizing center and signaling hub in animal cells. The past decades have witnessed the functional complexity and importance of centrosomes in various cellular processes such as cell shaping, division, and migration. In addition, centrosome abnormalities are linked to a wide range of human diseases and pathological states, such as cancer, reproductive disorder, brain disease, and ciliopathies. Herein, we discuss various functions of centrosomes in development and health, with an emphasis on their roles in germ cells, stem cells, and immune responses. We also discuss how centrosome dysfunctions are involved in diseases. A better understanding of the mechanisms regulating centrosome functions may lead the way to potential therapeutic targeting of this organelle in disease treatment.

Majewski/Microcephalic Osteodysplastic Primordial Dwarfism Type II (MOPDII) with generalised microdontia in the 4th millennium BCE Eastern Mediterranean

OBJECTIVE

This research evaluates the occurrence of generalised microdontia and proportionate osteodysplasia in human remains from a Chalcolithic cemetery with early evidence of metalworking in Cyprus (Souskiou-Laona; 3500-2800 BCE).

MATERIALS

Skeletal and dental remains from Tomb 236 Individual A, in comparison with other human remains from Souskiou-Laona (MNI: 203).

METHODS

Macroscopic, microscopic, and metric observation of osteodysplasia and microdontia.

RESULTS

Smaller than usual permanent teeth and adult long bones were discovered, with epiphyseal fusion complete. The cranium, and the zygomatic bones were smaller than other adult remains.

CONCLUSIONS

Differential diagnosis includes pituitary dwarfism and Majewski/Microcephalic Osteodysplastic Primordial Dwarfism Type II (MOPDII), which are two types of proportionate dwarfism with presentation of microdontia. This individual appears to display skeletal changes consistent with Majewski/Microcephalic Osteodysplastic Primordial Dwarfism Type II.

SIGNIFICANCE

This is the first case of MOPDII in the archaeological record worldwide, and it is the oldest case of proportionate dwarfism known to date. The presence of an adult probable female with primordial dwarfism at Chalcolithic cemetery of Souskiou-Laona indicates that mutations of the pericentrin (PCNT) gene were present in this early period.

LIMITATIONS

The remains of the individual were incomplete and poorly preserved.

SUGGESTIONS FOR FURTHER RESEARCH

Histology may lead to more detailed information on the individual's age and life story (osteobiography).

Microcephalic osteodysplastic primordial dwarfism type II is associated with global vascular disease

Background

Microcephalic osteodysplastic primordial dwarfism type II (MOPDII) is the most common form of primordial dwarfism, caused by bialleic mutations in the pericentrin gene (PCNT). Aside from its classic features, there are multiple associated medical complications, including a well-documented risk of neurovascular disease. Over the past several years, it has become apparent that additional vascular issues, as well as systemic hypertension and kidney disease may also be related to MOPDII. However, the frequency and extent of the vasculopathy was unclear. To help address this question, a vascular substudy was initiated within our Primordial Dwarfism Registry.

Results

Medical records from 47 individuals, living and deceased, ranging in age from 3 to 41years of age were interrogated for this purpose. Of the total group, 64% were diagnosed with moyamoya, intracranial aneurysms, or both. In general, the age at diagnosis for moyamoya was younger than aneurysms, but the risk for neurovascular disease was throughout the shortened lifespan. In addition to neurovascular disease, renal, coronary and external carotid artery involvement are documented. 43% of the total group was diagnosed with hypertension, and 17% had myocardial infarctions. A total of 32% of the entire cohort had some form of chronic kidney disease, with 4% of the total group necessitating a kidney transplant. In addition, 38% had diabetes/insulin resistance. Ages of diagnoses, treatment modalities employed, and location of vasculopathies were notated as available and applicable, as well as frequencies of other comorbidities.

Conclusions

It is now clear that vascular disease in MOPDII is global and screening of the cardiac and renal vessels is warranted along with close monitoring of blood pressure. We recommend a blood pressure of 110/70mmHg as a starting point for an upper limit, especially if the individual has a history of neurovascular disease, chronic kidney disease and/or diabetes. Additionally, providers need to be at high alert for the possibility of myocardial infarctions in young adults with MOPDII, so that appropriate treatment can be initiated promptly in an acute situation.

Siblings With Familial Dwarfism Presenting With Acute Myocardial Infarction at Adolescence

We encountered siblings with familial Majewski osteodysplastic primordial dwarfism type II (MOPD II) with acute myocardial infarction in adolescence and in their early 20s. We successfully performed percutaneous and surgical coronary interventions. From these cases, we were able to better understand coronary artery disease of MOPD II and provide better management. (Level of Difficulty: Intermediate.)

Novel compound heterozygous mutations of PCNT gene in MOPD type II with central precocious puberty

We report on a 6-year and 11-month old girl with short stature, microcephaly, proboscis nose, small teeth, left breast Tanner stage II, and nasopharynx adenoid hypertrophy. Her gestational age was 37 weeks and birth weight was 800 g. Her growth hormone peak was higher than 35.2 ng/ml, luteinizing hormone peak 8.97 IU/l, and blood glucose of 120 min 7.82 mmol/l in oral glucose tolerance test. Genetic testing revealed two novel heterozygous mutations in the PCNT gene, an insertion mutation at c.1828dupT (p.S610Ffs*32), and a splice site mutation at c.1207 + 1G>A, which were inherited from healthy carrier patients. This case shows that MOPDII can be associated with central precocious puberty and impaired glucose tolerance in addition to intrauterine growth restriction, postpartum growth defect, and microcephaly.

The essential role of primary cilia in cerebral cortical development and disorders

Primary cilium, first described in the 19th century in different cell types and organisms by Alexander Ecker, Albert Kolliker, Aleksandr Kowalevsky, Paul Langerhans, and Karl Zimmermann (Ecker, 1844; Kolliker, 1854; Kowalevsky, 1867; Langerhans, 1876; Zimmermann, 1898), play an essential modulatory role in diverse aspects of nervous system development and function. The primary cilium, sometimes referred to as the cell's 'antennae', can receive wide ranging inputs from cellular milieu, including morphogens, growth factors, neuromodulators, and neurotransmitters. Its unique structural and functional organization bequeaths it the capacity to hyper-concentrate signaling machinery in a restricted cellular domain approximately one-thousandth the volume of cell soma. Thus enabling it to act as a signaling hub that integrates diverse developmental and homestatic information from cellular milieu to regulate the development and function of neural cells. Dysfunction of primary cilia contributes to the pathophysiology of several brain malformations, intellectual disabilities, epilepsy, and psychiatric disorders. This review focuses on the most essential contributions of primary cilia to cerebral cortical development and function, in the context of neurodevelopmental disorders and malformations. It highlights the recent progress made in identifying the mechanisms underlying primary cilia's role in cortical progenitors, neurons and glia, in health and disease. A future challenge will be to translate these insights and advances into effective clinical treatments for ciliopathies.

Identification of three novel mutations in PCNT in vietnamese patients with microcephalic osteodysplastic primordial dwarfism type II

BACKGROUND

Primordial dwarfism (PD) is a group of genetically heterogeneous disorders related to developmental disabilities occurring in the uterus and prolongs during all stages of life, resulting in short stature, facial deformities and abnormal brain.

OBJECTIVE

To determine the exact cause of the disease in two Vietnamese patients priory diagnosed with PD by severe pre-and postnatal growth retardation with marked microcephaly and some bone abnormalities.

METHODS

Whole-exome sequencing was performed for the two patients and mutations in genes related to PD were screened. Sanger sequencing was applied to examine the mutations in the patients of their families.

RESULTS

Three novel mutations in the PCNT gene which have not been reported previously were identified in the two patients. Of which, two frameshift mutations (p.Thr479Profs*6 and p.Glu2742Alafs*8) were detected in patient I and one stop-gained mutation (p.Gln1907*) was detected in the patient II. These mutations may result in a truncated PCNT protein, leading to an inactivated PACT domain corresponding to residue His3138-Trp3216 of PCNT protein. Therefore, the three mutations may cause a deficiency of protein functional activity and result in the phenotypes of primordial dwarfism in the two patients.

CONCLUSIONS

Clinical presentations in combination with genetic analyses supported an accurate diagnosis of the two patients with microcephalic osteodysplastic primordial dwarfism type II (MOPD II). In addition, these results have important implications for prenatal genetic screening and genetic counseling for the families.

Progenitor death drives retinal dysplasia and neuronal degeneration in a mouse model of ATRIP-Seckel syndrome

Seckel syndrome is a type of microcephalic primordial dwarfism (MPD) that is characterized by growth retardation and neurodevelopmental defects, including reports of retinopathy. Mutations in key mediators of the replication stress response, the mutually dependent partners ATR and ATRIP, are among the known causes of Seckel syndrome. However, it remains unclear how their deficiency disrupts the development and function of the central nervous system (CNS). Here, we investigated the cellular and molecular consequences of ATRIP deficiency in different cell populations of the developing murine neural retina. We discovered that conditional inactivation of Atrip in photoreceptor neurons did not affect their survival or function. In contrast, Atrip deficiency in retinal progenitor cells (RPCs) led to severe lamination defects followed by secondary photoreceptor degeneration and loss of vision. Furthermore, we showed that RPCs lacking functional ATRIP exhibited higher levels of replicative stress and accumulated endogenous DNA damage that was accompanied by stabilization of TRP53. Notably, inactivation of Trp53 prevented apoptosis of Atrip-deficient progenitor cells and was sufficient to rescue retinal dysplasia, neurodegeneration and loss of vision. Together, these results reveal an essential role of ATRIP-mediated replication stress response in CNS development and suggest that the TRP53-mediated apoptosis of progenitor cells might contribute to retinal malformations in Seckel syndrome and other MPD disorders.This article has an associated First Person interview with the first author of the paper.

Kleinwuchssyndrome – potenziell lebensbedrohliche Erkrankungen

Hintergrund

Es gibt viele Ursachen für einen Kleinwuchs. Kleinwuchs in Kombination mit einer intrauterinen Wachstumsretardierung (IUGR), einer Entwicklungsverzögerung und/oder ungewöhnlichen Stigmata sollte immer auch an eine syndromale Ursache denken lassen.

Fragestellung

Diese Arbeit soll für Kleinwuchssyndrome sensibilisieren, deren Diagnose aufgrund der potenziell lebensbedrohlichen Folgen möglichst frühzeitig gestellt werden sollte.

Material und Methoden

Die vorliegende Arbeit wurde auf Basis klinikinterner Fallberichte vor dem Hintergrund der aktuellen Literatur erstellt.

Ergebnisse

Das PTEN-Hamartom-Tumor-Syndrom (PHTS), das Bloom-Syndrom (BS), der mikrozephale osteodysplastische primordiale Kleinwuchs Typ II (MOPD-II-Syndrom) sowie das Ligase-IV-Syndrom (Lig4-Syndrom) sind seltene Kleinwuchssyndrome mit potenziell letalem Ausgang. Gemeinsame Merkmale liegen in einer Abweichung des Kopfumfangs (KU) und einer Entwicklungsverzögerung. Die Verdachtsdiagnose wird molekulargenetisch gesichert. Die Behandlung erfolgt in erster Linie symptomorientiert, für das PHTS und das Ligase-IV-Syndrom existieren darüber hinaus bereits kausale Therapieansätze. Für alle Syndrome gibt es Empfehlungen im Hinblick auf gezielte Vorsorgeuntersuchungen.

Schlussfolgerung

Bei entsprechenden Hinweisen auf einen syndromalen Kleinwuchs sollte zügig eine molekulargenetisch gestützte Diagnostik erfolgen, um rechtzeitig geeignete Therapieoptionen und Vorsorgeprogramme initiieren zu können.

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.

Renal Dysplasia and Precocious Diabetes Onset in Microcephalic Osteodysplastic Primordial Dwarfism Type II Syndrome: A Case Report

Microcephalic osteodysplastic primordial dwarfism type II (MOPDII) is a genetic syndrome. Its main characteristics are bony dysplasia, prenatal and postnatal growth deficiencies, microcephaly, and cerebrovascular disease. Several other features have been added recently. We report an individual with MOPDII affected by congenital renal dysplasia and hyperosmolar coma diabetic onset. Renal dysplasia has not been previously described in individuals with MOPDII. By publishing cases of unusual genetic disorders, it will be possible to broaden the spectrum of these rare syndromes, and improve the diagnosis and management of comorbidities.

Novel PCNT variants in MOPDII with attenuated growth restriction and pachygyria

Biallelic loss‐of‐function mutations in the centrosomal pericentrin gene (PCNT) cause microcephalic osteodysplastic primordial dwarfism type II (MOPDII), which is characterized by extreme growth retardation, microcephaly, skeletal dysplasia, and dental anomalies. Life expectancy is reduced due to a high risk of cerebral vascular anomalies. Here, we report two siblings with MOPDII and attenuated growth restriction, and pachygyria. Compound heterozygosity for two novel truncated PCNT variants was identified. Both truncated PCNT proteins were expressed in patient's fibroblasts, with a reduced total protein amount compared to control. Patient's fibroblasts showed impaired cell cycle progression. As a novel finding, 20% of patient's fibroblasts were shown to express PCNT comparable to control. This was associated with normal mitotic morphology and normal co‐localization of mutated PCNT with centrosome‐associated proteins γ‐tubulin and centrin 3, suggesting some residual function of truncated PCNT proteins. These data expand the clinical and molecular spectrum of MOPDII and indicate that residual PCNT function might be associated with attenuated growth restriction in MOPDII.

Intracranial aneurysms in microcephalic primordial dwarfism: a systematic review

BACKGROUND

Microcephalic primordial dwarfism (MPD) is a heterogeneous group of rare disorders. Recent studies have reported a significant percentage of patients with MPD suffering from a spectrum of cerebrovascular abnormalities, including intracranial aneurysms (IAs) and moyamoya syndrome. The neurological literature has not as yet specifically assessed IAs in this population. This systematic review aimed to assess the clinical behavior, characteristics, treatment modalities and outcomes of IAs in patients with MPD.

METHODS

We performed a systematic search in PubMed, Ovid MEDLINE and Ovid EMBASE for cases of MPD with IAs. We included three illustrative cases from our institution.

RESULTS

Twenty-four patients with 71 aneurysms were included in this study. Twelve patients (50%) presented with subarachnoid hemorrhage. The majority of patients were aged ≤18 years (70.8%), with a mean age of 16.2 years at presentation. Median aneurysm size was 3 (IQR 1.8-6) mm, and the most frequent locations were the internal carotid (37.3%) and middle cerebral arteries (23.8%). Concomitant moyamoya disease was reported in nine (37.5%) patients. Median age of aneurysm detection in screened patients was significantly lower than in non-screened patients (P=0.02). Microsurgical clipping (55.3%) and endovascular coiling (26.3%) were the most used modalities. Twenty-two cases were managed conservatively. Overall, mortality occurred in 45.8% of cases.

CONCLUSIONS

Screening for cerebrovascular disease seems reasonable and effective to detect aneurysms at an earlier age in this population. Efforts in the literature to emphasize early and regular screening for these patients can positively impact outcomes in this population, however more evidence is needed.

An apparent new syndrome of extreme short stature, microcephaly, dysmorphic faces, intellectual disability, and a bone dysplasia of unknown etiology

We report on a 26-year-old male with extreme short stature, microcephaly, macroglossia, other dysmorphic features, severe intellectual disability, and a bone dysplasia. The patient had an extensive genetic and biochemical evaluation that was all normal or noninformative. Recently, the proband died following a period of not eating. He likely had a previously undescribed syndrome of unknown etiology.

Microcephalic osteodysplastic primordial dwarfism type II: Additional nine patients with implications on phenotype and genotype correlation

PCNT encodes a large coiled- protein localizing to pericentriolar material and is associated with microcephalic osteodysplastic primordial dwarfism type II syndrome (MOPD II). We report our experience of nine new patients from seven unrelated consanguineous Egyptian families with the distinctive clinical features of MOPD II in whom a customized NGS panel showed homozygous truncating variants of PCNT. The NGS panel results were validated thereafter using Sanger sequencing revealing three previously reported and three novel PCNT pathogenic variants. The core phenotype appeared homogeneous to what had been reported before although patients differed in the severity showing inter and intra familial variability. The orodental pattern showed atrophic alveolar ridge (five patients), rootless tooth (four patients), tooth agenesis (three patients), and malformed tooth (three patients). In addition, mesiodens was a novel finding found in one patient. The novel c.9394-1G>T variant was found in two sibs who had tooth agenesis. CNS anomalies with possible vascular sequelae were documented in two male patients (22.2%). Simplified gyral pattern with poor development of the frontal horns of lateral ventricles was seen in four patients and mild thinning of the corpus callosum in two patients. Unilateral coronal craniosynstosis was noted in one patient and thick but short corpus callosum was an unusual finding noted in another. The later has not been reported before. Our results refine the clinical, neuroradiological, and orodental features and expand the molecular spectrum of MOPD II.

Centrosomes: The good and the bad for brain development

Centrosomes nucleate and organise the microtubule cytoskeleton in animal cells. These membraneless organelles are key structures for tissue organisation, polarity and growth. Centrosome dysfunction, defined as deviation in centrosome numbers and/or structural integrity, has major impact on brain size and functionality, as compared with other tissues of the organism. In this review, we discuss the contribution of centrosomes to brain growth during development. We discuss in particular the impact of centrosome dysfunction in Drosophila and mammalian neural stem cell division and fitness, which ultimately underlie brain growth defects.

A Novel PCNT Frame Shift Variant (c.7511delA) Causing Osteodysplastic Primordial Dwarfism of Majewski Type 2 (MOPD II)

Background: Microcephalic osteodysplastic primordial dwarfism type II (MOPD II) is an autosomal recessive and skeletal disorder included wide spectrum of clinical abnormalities such as fetal growth restriction, disproportionate face, microcephaly, post-natal growth retardation, adult height under 100 cm, abnormal skin pigmentation, insulin resistance, and susceptibility to cerebrovascular and hematologic abnormalities. Due to heterogeneous feature of MOPDs diseases and common clinical features among the different subtypes, mutation analysis can be considered as fundamental in the accurate diagnosis and confirmation of the MOPD II disease. Some studies revealed that, variants of gene encoding Pericentrin protein, PCNT, were associated with MOPD II. Methods: We performed whole exome sequencing based on the next generation sequencing (Illumina platform), to perform correct diagnosis in a 17-year-old girl with an unknown disease who was referred to the Diabetes Research Center in Yazd, Iran. The clinical features of the patient were short stature, generalized brachydactyly, gradual deterioration of brain functioning, menstrual irregularity, clitoromegaly, acanthosis nigricans, diabetes mellitus, hyperinsulinemia, insulin resistance, and dyslipidemia. Accordingly, her parents were also first cousin with no background disease. After identifying the novel variant, it was confirmed in the proband and her family using bi-directional Sanger sequencing, and its pathogenicity was also checked by different online tools. Results: Our study revealed a novel frame-shift variant in PCNT gene (c.7511delA, p.K2504Sfs^*27), which causes premature termination of Pericentrin protein. The result disclosed that, the proband was affected by MOPD II disease. In addition, the Sanger sequencing confirmed the novel homozygote variant in the proband and heterozygote one in her parents, and the extended family perfectly segregated among them. Online tools such as Varsome and MutationTaster also showed a high level of pathogenicity for the variant identified. Conclusion: A novel variant was identified in the proband and her extended family, which emphasized the importance of PCNT gene mutations analysis in the screening and accurate identification of MOPD II disease, especially in prenatal diagnosis.

Ocular characteristics in a variant microcephalic primordial dwarfism type II

BACKGROUND

Microcephalic osteodysplastic primordial dwarfism, type II (MOPD II) is a rare disease that is assumed to be caused by a pericentrin (PCNT) gene mutation. Clinical manifestations have been reported in pediatrics and neurology; however, only a few ocular findings have been documented.

CASE PRESENTATION

We present three unrelated cases of MOPD II with similar facial features and short stature. Unlike the cases described in the literature, all subjects had normal birth weight and height but their growth was retarded thereafter. In addition to delayed milestones, they have a broad forehead, maxillary protrusion, long peaked nose, high nasal bridge, low-set large ears, extreme reromicrogenia, and normal-sized teeth. These three patients had similar ocular manifestations with the short axial length associated with high hyperopia more than + 9 diopters (D) and macular scarring. The oldest subject was a 20 year-old male without neurological symptoms. One female subject had developed alopecia during the previous 2 years. The other female subject had moyamoya disease, but a genetic study revealed a normal PCNT gene.

CONCLUSION

This is the first report of MOPD II focusing on ocular findings, suggesting that macular dystrophy and high hyperopia are the common ocular characteristics of MOPD II. Prompt referral to an ophthalmologist is essential. Although refractive amblyopia can be treated with optical correction, visual prognosis may be poor due to maculopathy.

Microcephalic osteodyplastic primordial dwarfism type II: case report with unique oral findings and a new mutation in the pericentrin gene

OBJECTIVE

Microcephalic osteodysplastic dwarfism (MOPD) type II (OMIM 210720) is a rare autosomal recessive form of primordial dwarfism, characterized by intrauterine and postnatal growth restriction, microcephaly, distinctive facial features, and osteodysplastic skeletal changes. The dental literature describing the oral manifestations of this syndrome is scarce.

STUDY DESIGN

The aim of this article is to report the case of an 8-year-old male of Indian origin with MOPD type II and to describe his oral and dental manifestations. Genetic analysis was performed to confirm the diagnosis.

RESULTS

The patient presented with interesting dental findings, including oligodontia, enamel hypoplasia, early exfoliation of primary dentition, accelerated eruption of permanent teeth with generalized grade II mobility, histopathologic features suggestive of dentin dysplasia, and a new mutation in the Pericentrin gene, which has not been documented earlier.

CONCLUSIONS

This is the first report from India of a case with this syndrome. The article presents various dentomaxillofacial features that have not been documented in dental literature earlier with sufficient evidence.

Characteristics and Treatment Outcome of Intracranial Aneurysms in Children and Adolescents

Objective

Intracranial aneurysms are not common in young age patients. We sought to find the characteristics of the intracranial aneurysms in patients under 20 years of age.

Methods

We reviewed 23 consecutive patients ≤20 years of age treated for their intracranial aneurysms during the period from 1995 to 2017. From medical records and imaging studies, we gathered data on age, sex, presentation, associated medical condition, location and characteristics of aneurysms, treatment and clinical outcomes.

Results

The patients’ ages ranged from 13 months to 20 years (median, 14 years). There were 16 males and seven females (male to female ratio, 2.3 : 1) with 31 aneurysms. Clinical presentations included sudden severe headache in 61%, followed by altered mentality in 17% and seizure in 17%. More than one-fourth patients had specific medical conditions related to the development of the cerebral aneurysms. The majority of aneurysms occurred in the anterior circulation (71%), and were saccular (71%). There were each three patients with false aneurysms (13%) and giant aneurysms (13%), and only one patient with multiple aneurysms (4%). We treated 22 patients : 21 aneurysms with the endovascular methods, three with open surgery, and one with combined treatment. Good functional outcome could be achieved in 86% during the follow-up period.

Conclusion

In this series, the young-age patients with intracranial aneurysms were characterized by male predominance, related specific medical conditions, low incidence of multiple aneurysms, high incidence of giant aneurysms and good functional outcome after treatment.

Majewski dwarfism type II: an atypical neuroradiological presentation with a novel variant in the PCNT gene

Microcephalic osteodysplastic primordial dwarfism syndrome II (MOPDII) is microcephalic primordial dwarfism and is a very rare form of disproportionate short stature. This disorder shares common features with other forms of microcephalic primordial dwarfism, including severe prenatal and postnatal growth retardation with marked microcephaly. However, it includes characteristic skeletal dysplasia, abnormal dentition and increased risk for cerebrovascular diseases. Recent reports added more features, including café-au-lait lesions, cutis marmorata, astigmatism, Moyamoya disease, insulin resistance, obesity, abnormal skin pigmentation and acanthosis nigricans around the neck. Clearly, the more MOPDII reports that are produced, the more information will be added to the spectrum of MOPDII features that can improve our understanding of this disorder. In this paper, we reported a new case of MOPDII with more severe clinical features, earlier onset of common features, in addition to a homozygous novel variant in the PCNT gene.

Cenpj Regulates Cilia Disassembly and Neurogenesis in the Developing Mouse Cortex

Primary cilia are microtubule-based protuberances that project from the eukaryotic cell body to sense the extracellular environment. Ciliogenesis is closely correlated to the cell cycle and defects of cilia are related to human systemic diseases such as primary ciliary dyskinesia. However, the role of ciliogenesis in cortical development remains unclear. Here, we demonstrate that Cenpj, a protein that is required for centriole biogenesis, plays a role in regulating cilium disassembly in vivo Depletion of Cenpj in neural progenitor cells results in long cilia and abnormal cilia disassembly. Radial glial cells Cenpj depletion exhibit uncompleted cell division, reduced cell proliferation, and increased cell apoptosis in the developing mouse cerebrum cortex, leading to microcephaly. In addition, Cenpj depletion causes long and thin primary cilia and motile cilia in adult neural stem cells and reduced cell proliferation in the subventricular zone. Furthermore, we show that Cenpj regulates cilia disassembly and neurogenesis through Kif2a, a plus-end-directed motor protein. These data collected from mice of both sexes provide insights into how ciliogenesis plays roles in cortical development and how primary microcephaly is induced by Cenpj mutations in humans.SIGNIFICANCE STATEMENT Autosomal recessive primary microcephaly is a neurodevelopmental disorder with the major symptoms of reduction of circumference of the head, brain volume, and cortex thickness with normal brain architecture in birth. We used conditional Cenpj deletion mice and found that neural progenitor cells (NPCs) exhibited long primary cilia and abnormal cilium appendages. The defective cilium disassembly caused by Cenpj depletion might correlate to reduced cell proliferation, uncompleted cell division, cell apoptosis, and microcephaly in mice. Cenpj also regulates the cilium structure of adult neural stem cells and adult neurogenesis in mice. Additionally, our results illustrate that Cenpj regulates cilia disassembly and neurogenesis through Kif2a, indicating that primary cilia dynamics play a crucial role in NPC mitosis and adult neurogenesis.

PCNT point mutations and familial intracranial aneurysms

OBJECTIVE

To identify novel genes involved in the etiology of intracranial aneurysms (IAs) or subarachnoid hemorrhages (SAHs) using whole-exome sequencing.

METHODS

We performed whole-exome sequencing in 13 individuals from 3 families with an autosomal dominant IA/SAH inheritance pattern to look for candidate genes for disease. In addition, we sequenced PCNT exon 38 in a further 161 idiopathic patients with IA/SAH to find additional carriers of potential pathogenic variants.

RESULTS

We identified 2 different variants in exon 38 from the PCNT gene shared between affected members from 2 different families with either IA or SAH (p.R2728C and p.V2811L). One hundred sixty-four samples with either SAH or IA were Sanger sequenced for the PCNT exon 38. Five additional missense mutations were identified. We also found a second p.V2811L carrier in a family with a history of neurovascular diseases.

CONCLUSION

The PCNT gene encodes a protein that is involved in the process of microtubule nucleation and organization in interphase and mitosis. Biallelic loss-of-function mutations in PCNT cause a form of primordial dwarfism (microcephalic osteodysplastic primordial dwarfism type II), and ≈50% of these patients will develop neurovascular abnormalities, including IAs and SAHs. In addition, a complete Pcnt knockout mouse model (Pcnt ^-/-) published previously showed general vascular abnormalities, including intracranial hemorrhage. The variants in our families lie in the highly conserved PCNT protein-protein interaction domain, making PCNT a highly plausible candidate gene in cerebrovascular disease.

A Recurrent De Novo Heterozygous COG4 Substitution Leads to Saul-Wilson Syndrome, Disrupted Vesicular Trafficking, and Altered Proteoglycan Glycosylation

The conserved oligomeric Golgi (COG) complex is involved in intracellular vesicular transport, and is composed of eight subunits distributed in two lobes, lobe A (COG1-4) and lobe B (COG5-8). We describe fourteen individuals with Saul-Wilson syndrome, a rare form of primordial dwarfism with characteristic facial and radiographic features. All affected subjects harbored heterozygous de novo variants in COG4, giving rise to the same recurrent amino acid substitution (p.Gly516Arg). Affected individuals' fibroblasts, whose COG4 mRNA and protein were not decreased, exhibited delayed anterograde vesicular trafficking from the ER to the Golgi and accelerated retrograde vesicular recycling from the Golgi to the ER. This altered steady-state equilibrium led to a decrease in Golgi volume, as well as morphologic abnormalities with collapse of the Golgi stacks. Despite these abnormalities of the Golgi apparatus, protein glycosylation in sera and fibroblasts from affected subjects was not notably altered, but decorin, a proteoglycan secreted into the extracellular matrix, showed altered Golgi-dependent glycosylation. In summary, we define a specific heterozygous COG4 substitution as the molecular basis of Saul-Wilson syndrome, a rare skeletal dysplasia distinct from biallelic COG4-CDG.

Drosophila PLP assembles pericentriolar clouds that promote centriole stability, cohesion and MT nucleation

Pericentrin is a conserved centrosomal protein whose dysfunction has been linked to several human diseases. It has been implicated in many aspects of centrosome and cilia function, but its precise role is unclear. Here, we examine Drosophila Pericentrin-like-protein (PLP) function in vivo in tissues that form both centrosomes and cilia. Plp mutant centrioles exhibit four major defects: (1) They are short and have subtle structural abnormalities; (2) They disengage prematurely, and so overduplicate; (3) They organise fewer cytoplasmic MTs during interphase; (4) When forming cilia, they fail to establish and/or maintain a proper connection to the plasma membrane—although, surprisingly, they can still form an axoneme-like structure that can recruit transition zone (TZ) proteins. We show that PLP helps assemble “pericentriolar clouds” of electron-dense material that emanate from the central cartwheel spokes and spread outward to surround the mother centriole. We propose that the partial loss of these structures may largely explain the complex centriole, centrosome and cilium defects we observe in Plp mutant cells.

Centrioles are complex, microtubule (MT) based structures that organise two important cell organelles, the centrosome and the cilium. The centrosome is a major MT organising centre in many cell types, while the cilium functions as a cellular “antenna” responsible for regulating several cellular signalling pathways. Pericentrin is conserved centriole-binding protein that plays an important part in centrosome and cilium function, and mutations in the Pericentrin gene are linked to several human diseases. Here we use the fruit-fly Drosophila melanogaster to investigate how Pericentrin-Like-Protein (the fly homolog of Pericentrin) contributes to centriole, centrosome and cilium function. We find that Plp mutant fly centrioles have subtle structural defects, organize less microtubules, and do not properly migrate to the cell membrane to form cilia. We also observe that PLP helps assemble “pericentriolar clouds”—dense structures that emanate from the centriole, and appear to interact with microtubules, as well as connect existing centrioles to newly formed ones. In mutant flies these structures are significantly reduced in size. We propose that the defects in these PLP structures can explain most, if not all, the complex defects observed in Plp mutants.