FAM20C Overview: Classic and Novel Targets, Pathogenic Variants and Raine Syndrome Phenotypes.

FAM20C is a gene coding for a protein kinase that targets S-X-E/pS motifs on different phosphoproteins belonging to diverse tissues. Pathogenic variants of FAM20C are responsible for Raine syndrome (RS), initially described as a lethal and congenital osteosclerotic dysplasia characterized by generalized atherosclerosis with periosteal bone formation, characteristic facial dysmorphisms and intracerebral calcifications. The aim of this review is to give an overview of targets and variants of FAM20C as well as RS aspects. We performed a wide phenotypic review focusing on clinical aspects and differences between all lethal (LRS) and non-lethal (NLRS) reported cases, besides the FAM20C pathogenic variant description for each. As new targets of FAM20C kinase have been identified, we reviewed FAM20C targets and their functions in bone and other tissues, with emphasis on novel targets not previously considered. We found the classic lethal and milder non-lethal phenotypes. The milder phenotype is defined by a large spectrum ranging from osteonecrosis to osteosclerosis with additional congenital defects or intellectual disability in some cases. We discuss our current understanding of FAM20C deficiency, its mechanism in RS through classic FAM20C targets in bone tissue and its potential biological relevance through novel targets in non-bone tissues.

Case Fatality Rate Related to Microcephaly Congenital Zika Syndrome and Associated Factors: A Nationwide Retrospective Study in Brazil †.

BACKGROUND: The clinical manifestations of microcephaly/congenital Zika syndrome (microcephaly/CZS) have harmful consequences on the child's health, increasing vulnerability to childhood morbidity and mortality. This study analyzes the case fatality rate and child-maternal characteristics of cases and deaths related to microcephaly/CZS in Brazil, 2015-2017. METHODS: Population-based study developed by linkage of three information systems. We estimate frequencies of cases, deaths, case fatality rate related to microcephaly/CZS according to child and maternal characteristics and causes of death. Multivariate logistic regression models were applied. RESULTS: The microcephaly/CZS case fatality rate was 10% (95% CI 9.2-10.7). Death related to microcephaly/CZS was associated to moderate (OR = 2.15; 95% CI 1.63-2.83), and very low birth weight (OR = 3.77; 95% CI 2.20-6.46); late preterm births (OR = 1.65; 95% CI 1.21-2.23), Apgar < 7 at 1st (OR = 5.98; 95% CI 4.46-8.02) and 5th minutes (OR = 4.13; 95% CI 2.78-6.13), among others. CONCLUSIONS: A high microcephaly/CZS case fatality rate and important factors associated with deaths related to this syndrome were observed. These results can alert health teams to these problems and increase awareness about the factors that may be associated with worse outcomes.

Clinical, molecular, and pathological findings in a Neu-Laxova syndrome stillborn: A Brazilian case report.

Neu-Laxova syndrome (NLS) is a lethal genetic multiple congenital anomaly syndrome of unknown prevalence representing the severe spectrum of serine biosynthesis defects associated with PHGDH, PSAT1, or PSP gene mutations. The purpose of this study was to describe clinical/molecular and pathologic features of a NLS case caused by novel heterozygous missense variant in PHGDH gene identified in his consanguineous parents.

Microcephaly infant mortality in Brazil before zika outbreak.

Introduction: We present temporal and spatial variation of deaths from microcephaly in children under 1 year of age is analyzed at regional, state, and municipal level in the pre-Zika period in Brazil. Materials and Methods: Data on births and deaths of infants with microcephaly was obtained from DATASUS from 1996 to 2013. Infant mortality rate from microcephaly (IMR-M) was estimated at Region, Federative Unit (UF), and Municipality level. Secular trend (ST) and risk of death variation were estimated using a Poisson regression model. Satscan software was used to obtain a statistic spatial scan for the Poisson model. Results: IMR-M shows a non-significant negative ST in the Southeast, South and Central West Regions of Brazil. A greater IMR-M risk of death variation is found in the North and Northeast Regions. Most UFs in the Southeast, South and Central West Regions showed a negative ST, in contrast to what occurs in the UFs of the North and Northeast Regions showed a positive ST. Six high risk significant clusters were found: 3 in the North-Northeast and 3 in the South-SouthWest-Center-West. Conclusions: The North and Northeast Regions showed positive ST for IRM-M and higher death risk, which was not observed in the other regions. Cluster distribution for higher IMR-M and risk resembles the distribution of the microcephaly and Zika cases in the outbreak period.

Introducción: Presentamos la variación temporal y espacial de las muertes por microcefalia en niños menores de 1 año de edad que se analizan a nivel regional, estatal y municipal en el período pre-Zika en Brasil. Materiales y métodos: Los datos sobre nacimientos y muertes de niños con microcefalia se obtuvieron de DATASUS de 1996 a 2013. La tasa de mortalidad infantil por microcefalia (TMI-M) se estimó a nivel de Región, Unidad de Federativa (UF) y Municipio. La tendencia secular (TS) y la variación del riesgo de muerte se estimaron utilizando un modelo de regresión de Poisson. El análisis estadístico espacial fue realizado por un modelo de Poisson utilizando el software Satscan. Resultados: La TMI-M muestra un TS negativo no significativo en las regiones sudeste, sur y centro-oeste de Brasil. Una mayor variación de riesgo de muerte se encuentra en las regiones Norte y Noreste. La mayoría de las UF en las regiones Sureste, Sur y Centro-Oeste mostraron un TS negativa, en contraste con lo que ocurre en las UF de las Regiones Norte y Noreste mostraron una TS positiva. Se encontraron seis agrupamientos significativos de alto riesgo: 3 en el Norte-Noreste y 3 en el Sur-Sur-Oeste-Centro-Oeste. Conclusiones Las regiones Norte y Noreste mostraron una TS positiva para la TMI-M y un mayor riesgo de muerte, que no se observó en las otras regiones. La distribución de los agrupamientos de mayor TMI-M y riesgo se asemeja a la distribución de los casos de microcefalia y Zika en el período del brote. Conclusiones: Las regiones Norte y Noreste mostraron una TS positiva para la TMI-M y un mayor riesgo de muerte, que no se observó en las otras regiones. La distribución de los agrupamientos de mayor TMI-M y riesgo se asemeja a la distribución de los casos de microcefalia y Zika en el período del brote.

Novel homozygous OSGEP gene pathogenic variants in two unrelated patients with Galloway-Mowat syndrome: case report and review of the literature.

BACKGROUND: Galloway-Mowat syndrome (GAMOS) is a rare autosomal recessive disorder characterized by early-onset nephrotic syndrome and microcephaly with brain anomalies. WDR73 pathogenic variants were described as the first genetic cause of GAMOS and, very recently, four novel causative genes, OSGEP, LAGE3, TP53RK, and TPRKB, have been identified. CASE PRESENTATION: We present the clinical and genetic characteristics of two unrelated infants with clinical suspicion of GAMOS who were born from consanguineous parents. Both patients showed a similar clinical presentation, with early-onset nephrotic syndrome, microcephaly, brain atrophy, developmental delay, axial hypotonia, and early fatality. We identified two novel likely disease-causing variants in the OSGEP gene. These two cases, in conjunction with the findings of a literature review, indicate that OSGEP pathogenic variants are associated with an earlier onset of nephrotic syndrome and shorter life expectancy than WDR73 pathogenic variants. CONCLUSIONS: Our findings expand the spectrum of pathogenic variants in the OSGEP gene and, taken in conjunction with the results of the literature review, suggest that the OSGEP gene should be considered the main known monogenic cause of GAMOS. Early genetic diagnosis of GAMOS is of paramount importance for genetic counseling and family planning.

Congenital Zika Syndrome: The Main Cause of Death and Correspondence Between Brain CT and Postmortem Histological Section Findings From the Same Individuals.

In the present case series, the cause of death of infants diagnosed with congenital Zika syndrome (CZS) was lung disease (pneumonia and sepsis with massive pulmonary aspiration), probably secondary to dysphagia and reflux. The main findings in infants with a confirmed diagnosis of CZS who died were as follows: (1) calcification and hypoplasia of the lentiform nuclei, hypoplasia of the caudate nuclei, and calcification at the cortical-subcortical junction was noted in all cases (100%) and calcification of the caudate nuclei was noted in 66.7% of cases; (2) calcification in the brainstem and along the lateral wall of the lateral ventricles was noted in only the case with arthrogryposis (33.3%); and (3) lesions in the posterior fossa (hypoplasia of the brainstem and cerebellum) were noted in two cases (66.7%), including the case with arthrogryposis. The findings concerning calcifications and brain malformations obtained from non-contrast computed tomography (CT) demonstrated good agreement with findings obtained from the postmortem pathological analysis; however, CT failed to detect discontinuity of the pia mater with heterotopia, invasion of the cerebral tissue into the subarachnoid space, and discontinuity of the ependyma in the lateral ventricles with gliosis; this last feature was only imaged in the most severe case of extreme microcephaly with a simplified gyral pattern. Only histopathology showed grouped calcifications associated with scattered calcifications suggestive of the neuron morphology.

Congenital microcephaly in Quebec: baseline prevalence, risk factors and outcomes in a large cohort of neonates.

OBJECTIVE: We assessed baseline prevalence, risk factors and outcomes of microcephaly in a large population of neonates. DESIGN: Retrospective cohort study. SETTING: All hospitals in the province of Quebec, Canada. PARTICIPANTS: 794 microcephalic and 1 944 010 non-microcephalic infants born between 1989 and 2012. MAIN OUTCOME MEASURES: Baseline prevalence of microcephaly and occurrence of other congenital anomalies. We estimated the association of (1) pregnancy risk factors including TORCH infections (toxoplasmosis, rubella, cytomegalovirus, herpes, other), exposure to teratogens, diabetes and maternal congenital anomalies with risk of microcephaly, and (2) microcephaly with risk of infant mortality and severe morbidity, adjusted for maternal characteristics. RESULTS: The overall prevalence of microcephaly was 4.1 per 10 000, ranging between 3.0 and 5.3 per 10 000 over time. Only 37% of microcephalic infants presented with other congenital anomalies. Maternal infection during pregnancy was the strongest risk factor, with 32 times the risk of microcephaly (prevalence ratio 32.38; 95% CI 22.42 to 46.75) compared with no infection. Exposure to teratogens was the next most important risk factor, with three times greater risk (prevalence ratio 3.10; 95% CI 2.37 to 4.07). Microcephaly was associated with 20 times the risk of infant mortality compared with no microcephaly (prevalence ratio 20.52; 95% CI 15.57 to 27.04) and significantly greater infant morbidity. CONCLUSIONS: In Canada, infectious exposure during pregnancy is a strong risk factor for microcephaly, and affected infants are at higher risk of poor birth outcomes. Better monitoring of microcephaly is needed in the event that Zika or other novel viruses affect future risk.

Chloroquine, a FDA-approved Drug, Prevents Zika Virus Infection and its Associated Congenital Microcephaly in Mice.

Zika virus (ZIKV) has become a global public health emergency due to its rapidly expanding range and its ability to cause severe congenital defects such as microcephaly. However, there are no FDA-approved therapies or vaccines against ZIKV infection. Through our screening of viral entry inhibitors, we found that chloroquine (CQ), a commonly used antimalarial and a FDA-approved drug that has also been repurposed against other pathogens, could significantly inhibit ZIKV infection in vitro, by blocking virus internalization. We also demonstrated that CQ attenuates ZIKV-associated morbidity and mortality in mice. Finally, we proved that CQ protects fetal mice from microcephaly caused by ZIKV infection. Our methodology of focusing on previously identified antivirals in screens for effectiveness against ZIKV proved to be a rapid and efficient means of discovering new ZIKV therapeutics. Selecting drugs that were previously FDA-approved, such as CQ, also improves the likelihood that they may more quickly reach stages of clinical testing and use by the public.

Microcephaly Case Fatality Rate Associated with Zika Virus Infection in Brazil: Current Estimates.

Considering the currently confirmed cases of microcephaly and related deaths associated with Zika virus in Brazil, the estimated case fatality rate is 8.3% (95% confidence interval: 7.2-9.6). However, a third of the reported cases remain under investigation. If the confirmation rates of cases and deaths are the same in the future, the estimated case fatality rate will be as high as 10.5% (95% confidence interval: 9.5-11.7).

[Spatial and temporal analysis of infant mortality from microcephaly in Argentina (1998-2012)]. / Analisis temporal y espacial de las muertes infantiles por microcefalia en Argentina (1998-2012).

Due to the increase in cases of microcephaly caused by Zika virus in Brazil, the Ministry of Health of Argentina recommends increasing surveillance of this malformation. In order to deepen the knowledge of the epidemiological behavior of microcephaly in the country, infant mortality by microcephaly is analyzed between 1998 and 2012. The data come from the Direction of Statistics and Health Information (DEIS). The infant mortality rate by microcephaly (IMR-M) was calculated by provinces and regions and a clustering analysis was performed at the departmental level. The highest rates were observed in the regions and provinces of the north of the country. The spatial distribution of IMR-M is related to the prevalence of microcephaly in newborns. This distribution is related to the greater poverty and consanguinity of the north of Argentina, synergic factors predisposing to the occurrence of congenital malformations in general and microcephaly in particular.

Debido al incremento de casos de microcefalia por virus Zika en Brasil el Ministerio de Salud de Argentina recomienda incrementar la vigilancia de esta malformación. A fin de profundizar el conocimiento del comportamiento epidemiológico de microcefalia en el país se analiza la mortalidad infantil por microcefalia entre 1998-2012. Los datos proceden de la Dirección de Estadísticas e Información de Salud (DEIS). Se calculó por provincias y regiones la tasa de mortalidad infantil por microcefalia (TMI-M) y se realizó un análisis de agrupamiento a nivel departamental. Las tasas más elevadas se observaron en las regiones y provincias del norte del país. La distribución espacial de la TMI-M guarda relación con las prevalencias de microcefalia en recién nacidos. Esta distribución se relaciona con la mayor pobreza y consanguinidad del norte de la Argentina, factores sinérgicos predisponentes de la ocurrencia de malformaciones congénitas en general y de microcefalia en particular.

Non lethal Raine syndrome and differential diagnosis.

Raine syndrome is a rare autosomal recessive bone dysplasia characterized by characteristic facial features with exophthalmos and generalized osteosclerosis. Amelogenesis imperfecta, hearing loss, seizures, and intracerebral calcification are apparent in some affected individuals. Originally, Raine syndrome was originally reported as a lethal syndrome. However, recently a milder phenotype, compatible with life, has been described. Biallelic variants inFAM20C, encoding aGolgi casein kinase involved in biomineralisation, have been identified in affected individuals. We report here a consanguineous Moroccan family with two affected siblingsa girl aged 18 and a boy of 15years. Clinical features, including learning disability, seizures and amelogenesis imperfecta, initially suggested a diagnosis of Kohlschutter-Tonz syndrome. However,a novel homozygous FAM20Cvariantc.676T > A, p.(Trp226Arg) was identified in the affected siblings. Our report reinforces that Raine syndrome is compatible with life, and that mild hypophosphatemia and amelogenesis imperfecta are key features of the attenuated form.

Ministério da Saúde confirma relação entre vírus Zika e microcefalia

O achado reforça o chamado para uma mobilização nacional para conter o mosquito transmissor, o Aedes aegypti, responsável pela disseminação doença. O Instituto Evandro Chagas, órgão do ministério em Belém (PA), encaminhou o resultado de exames realizados em um bebê, nascida no Ceará, com microcefalia e outras malformações congênitas. Em amostras de sangue e tecidos, foi identificada a presença do vírus Zika A partir desse achado do bebê que veio à óbito, o Ministério da Saúde considera confirmada a relação entre o vírus e a ocorrência de microcefalia. Essa é uma situação inédita na pesquisa científica mundial. As investigações sobre o tema devem continuar para esclarecer questões como a transmissão desse agente, a sua atuação no organismo humano, a infecção do feto e período de maior vulnerabilidade para a gestante. Em análise inicial, o risco está associado aos primeiros três meses de gravidez.

Compound heterozygous BRAT1 mutations cause familial Ohtahara syndrome with hypertonia and microcephaly.

Homozygous frameshift BRAT1 mutations were found in patients with lethal neonatal rigidity and multifocal seizure syndrome (MIM# 614498). Here, we report on two siblings with compound heterozygous mutations in BRAT1. They had intractable seizures from neonatal period, dysmorphic features and hypertonia. Progressive microcephaly was also observed. Initial electroencephalogram showed a suppression-burst pattern, leading to a diagnosis of Ohtahara syndrome. They both died from pneumonia at 1 year and 3 months, respectively. Whole-exome sequencing of one patient revealed a compound heterozygous BRAT1 mutations (c.176T>C (p.Leu59Pro) and c.962_963del (p.Leu321Profs*81)). We are unable to obtain DNA from another patient. The p.Leu59Pro mutation occurred at an evolutionarily conserved amino acid in a CIDE-N (N-terminal of an cell death-inducing DFF45-like effector) domain, which has a regulatory role in the DNA fragmentation pathway of apoptosis. Our results further support that mutations of BRAT1 could lead to epileptic encephalopathy.

Hereditary deletion of the entire FAM20C gene in a patient with Raine syndrome.

Raine syndrome is an autosomal recessive disorder caused by mutations in the FAM20C gene that is characterized by generalized osteosclerosis with periosteal new bone formation and distinctive craniofacial dysmorphism. We report on a child who is homozygous for a 487-kb deletion in 7p22.3 that contains FAM20C. Both parents were heterozygous for the deletion. Our patient had the common craniofacial features as well as, uncommon features such as protruding tongue, short stature, and hypoplastic distal phalanges. In addition, he had wormian bones and pyriform aperture stenosis, features that are usually under diagnosed. It is clear that Raine syndrome has a wide range of expression and may not be lethal in the neonatal period. Furthermore, Raine cases due to whole gene deletion do not seem to have a major difference in the phenotype over those caused by various mutations.

Centrosome amplification causes microcephaly.

Centrosome amplification is a hallmark of human tumours. In flies, extra centrosomes cause spindle position defects that result in the expansion of the neural stem cell (NSC) pool and consequently in tumour formation. Here we investigated the consequences of centrosome amplification during mouse brain development and homeostasis. We show that centrosome amplification causes microcephaly due to inefficient clustering mechanisms, where NSCs divide in a multipolar fashion producing aneuploid cells that enter apoptosis. Importantly, we show that apoptosis inhibition causes the accumulation of highly aneuploid cells that lose their proliferative capacity and differentiate, thus depleting the pool of progenitors. Even if these conditions are not sufficient to halt brain development, they cause premature death due to tissue degeneration. Our results support an alternative concept to explain the etiology of microcephaly and show that centrosome amplification and aneuploidy can result in tissue degeneration rather than overproliferation and cancer.

Inactivation of mTORC1 in the developing brain causes microcephaly and affects gliogenesis.

The mammalian target of rapamycin (mTOR) regulates cell growth in response to various intracellular and extracellular signals. It assembles into two multiprotein complexes: the rapamycin-sensitive mTOR complex 1 (mTORC1) and the rapamycin-insensitive mTORC2. In this study, we inactivated mTORC1 in mice by deleting the gene encoding raptor in the progenitors of the developing CNS. Mice are born but never feed and die within a few hours. The brains deficient for raptor show a microcephaly starting at E17.5 that is the consequence of a reduced cell number and cell size. Changes in cell cycle length during late cortical development and increased cell death both contribute to the reduction in cell number. Neurospheres derived from raptor-deficient brains are smaller, and differentiation of neural progenitors into glia but not into neurons is inhibited. The differentiation defect is paralleled by decreased Stat3 signaling, which is a target of mTORC1 and has been implicated in gliogenesis. Together, our results show that postnatal survival, overall brain growth, and specific aspects of brain development critically depend on mTORC1 function.

Amish lethal microcephaly: a new metabolic disorder with severe congenital microcephaly and 2-ketoglutaric aciduria.

A new metabolic disorder characterized by severe congenital microcephaly, death within the first year, and severe 2-ketoglutaric aciduria has been found among the Old-Order Amish of Lancaster County, Pennsylvania. Amish lethal microcephaly segregates as an autosomal recessive disorder and has an unusually high incidence of at least 1 in 500 births. When the infants are well, the urine organic acid profiles show isolated, extreme elevations of 2-ketoglutaric acid. However, during otherwise simple viral illnesses, the infants often develop a metabolic acidosis, which may follow a lethal course. Cranial magnetic resonance imaging of a single patient showed a smooth, immature brain similar to that of a 20-week fetus except for a moderate degree of cerebellar vermal hypoplasia. Assay of 2-ketoglutarate dehydrogenase in cultured lymphoblasts of one patient showed normal activity. Amish lethal microcephaly maps to 17q25 and may be caused by a defect in a mitochondrial inner membrane protein functioning as a 2-ketoglutarate transporter.

Patterns of first-year survival among infants with selected congenital anomalies in Texas, 1995-1997.

BACKGROUND: Few registry-based studies have investigated survival among infants with congenital anomalies. We conducted a registry-based study to examine patterns and probability of survival during the first year of life among infants with selected congenital anomalies. METHODS: Data from the Texas Birth Defects Monitoring Division were merged with linked birth-infant death files for 2,774 infants born January 1, 1995 to December 31, 1997, with at least 1 of 23 common anomalies. Deaths before the first birthday were assessed from infant death files. Kaplan-Meier was used to estimate first-year survival; first-year survival was assessed for specific anomalies and by the number of life-threatening anomalies. RESULTS: Overall, 80.8% of infants with these 23 anomalies survived the first year of life. We observed the highest survival rates for infants with gastroschisis (92.9%, 95% CI = 86.8, 96.3), trisomy 21 (92.3%, 95% CI = 89.5, 94.4) or cleft lip with or without cleft palate (87.6%, 95% CI = 84.0, 90.5). Infants with intermediate survival rates included those with microcephaly (79.7%; 95% CI = 73.6, 84.6), tetralogy of Fallot (75.0%; 95% CI = 65.5, 82.2), or with diaphragmatic hernia (72.8%; 95% CI = 61.8, 81.2). As expected, all infants with anencephaly and almost all infants with trisomy 13 or trisomy 18 died during the first year of life. First-year survival declined as the number of co-occurring life-threatening anomalies increased. CONCLUSIONS: Overall, first-year survival for infants with congenital anomalies was high. Additional population-based studies are needed to quantify improvements in first-year survival.