Marcus Gunn jaw-winking synkinesis (MGJWS) is characterized by eyelid ptosis, which disappears during jaw movement. Familial MGJWS is an extremely rare condition. Some authors suggested that MGJWS is due to neural misdirection in the brainstem whereas others suggested that aberrant reinnervation or ephapse may be responsible for synkinetic activity. Pathogenesis of this condition is therefore still unclear.
To investigate pathogenetic mechanism in familial MGJWS we performed neurophysiological (EMG, Blink Reflex, Recovery cycle of the R2 component of the blink reflex, Masseter inhibitory reflex, BAEPS and kinematic analysis) and neuroradiological (MRI, Diffusion Tensor Imaging) investigations in a member of a multigenerational family with autosomal dominant Marcus Gunn jaw-winking synkinesis (MGJWS). Kinematic analysis of eyelid and jaw movements disclosed a similar onset and offset of the eyelid and jaw in both the opening and closing phases. The excitability of brainstem circuits, as assessed by the blink reflex recovery cycle and recovery index, was normal. Diffusion Tensor Imaging revealed reduced fractional anisotropy within the midbrain tegmentum.
Kinematic and MRI findings point to a brainstem structural abnormality in our familial MGJWS patient thus supporting the hypothesis of a neural misdirection of trigeminal motor axons to the elevator palpebralis muscle.
Haploinsufficiency of TBX1, encoding a T-box transcription factor, is largely responsible for the physical malformations in velo-cardio-facial/DiGeorge/22q11.2 deletion syndrome (22q11DS) patients. Cardiovascular malformations in these patients are highly variable, raising the question as to whether DNA variations in the TBX1 locus on the remaining allele of 22q11.2, could be responsible. To test this, a large sample size is needed. The TBX1 gene was sequenced in 360 consecutive 22q11DS patients. Rare and common variations were identified. We did not detect enrichment in rare SNP number in those with or without a congenital heart defect. One exception was that there was increased number of very rare SNPs between those with normal heart anatomy compared to those with right-sided aortic arch or persistent truncus arteriosus, suggesting potentially protective roles in the SNPs for these phenotype enrichment groups. Nine common SNPs (MAF >0.05) were chosen and used to genotype the entire cohort of 1,022 22q11DS subjects. We did not find a correlation between common SNPs or haplotypes and cardiovascular phenotype. This work demonstrates that common DNA variations in TBX1 do not explain variable cardiovascular expression in 22q11DS patients, implicating existence of modifiers in other genes on 22q11.2 or elsewhere in the genome.
22q11.2 deletion syndrome; TBX1 sequencing; cardiovascular defects; genomic disorder
Noonan syndrome (NS) is among the most common non-chromosomal disorders affecting development and growth. NS is caused by aberrant RAS-MAPK signaling and is genetically heterogeneous, which explains, in part, the marked clinical variability documented for this Mendelian trait. Recently, we and others identified SOS1 as a major gene underlying NS. Here, we explored further the spectrum of SOS1 mutations and their associated phenotypic features. Mutation scanning of the entire SOS1 coding sequence allowed the identification of 30 different variants deemed to be of pathological significance, including 13 novel missense changes and in-frame indels. Various mutation clusters destabilizing or altering orientation of regions of the protein predicted to contribute structurally to the maintenance of autoinhibition were identified. Two previously unappreciated clusters predicted to enhance SOS1's recruitment to the plasma membrane, thus promoting a spatial reorientation of domains contributing to inhibition, were also recognized. Genotype-phenotype analysis confirmed our previous observations, establishing a high frequency of ectodermal anomalies and a low prevalence of cognitive impairment and reduced growth. Finally, mutation analysis performed on cohorts of individuals with nonsyndromic pulmonic stenosis, atrial septal defects and ventricular septal defects excluded a major contribution of germline SOS1 lesions to the isolated occurrence of these cardiac anomalies.
Noonan syndrome; NS; SOS1; mutation analysis; structural analysis; genotype-phenotype correlations
The inflammatory bowel diseases (IBD) Crohn’s disease and ulcerative colitis are common causes of morbidity in children and young adults in the western world. Here we report the results of a genome-wide association study in early-onset IBD involving 3,426 affected individuals and 11,963 genetically matched controls recruited through international collaborations in Europe and North America, thereby extending the results from a previous study of 1,011 individuals with early-onset IBD1. We have identified five new regions associated with early-onset IBD susceptibility, including 16p11 near the cytokine gene IL27 (rs8049439, P = 2.41 × 10−9), 22q12 (rs2412973, P = 1.55 × 10−9), 10q22 (rs1250550, P = 5.63 × 10−9), 2q37 (rs4676410, P = 3.64 × 10−8) and 19q13.11 (rs10500264, P = 4.26 × 10−10). Our scan also detected associations at 23 of 32 loci previously implicated in adult-onset Crohn’s disease and at 8 of 17 loci implicated in adult-onset ulcerative colitis, highlighting the close pathogenetic relationship between early- and adult-onset IBD.
Cohen syndrome is a rare, clinically variable autosomal recessive disorder characterized by mental retardation, postnatal microcephaly, facial dysmorphisms, ocular abnormalities and intermittent neutropenia. Mutations in the COH1 gene have been found in patients from different ethnic origins. However, a high percentage of patients have only one or no mutated allele. To investigate whether COH1 copy number changes account for missed mutations, we used multiplex ligation-dependent probe amplification (MLPA) to test a group of 14 patients with Cohen syndrome. This analysis has allowed us to identify multi-exonic deletions in 11 alleles and duplications in 4 alleles. Considering our previous study, COH1 copy number variations represent 42% of total mutated alleles. To our knowledge, COH1 intragenic duplications have never been reported in Cohen syndrome. The three duplications encompassed exons 4–13, 20–30 and 57–60, respectively. Interestingly, four deletions showed the same exon coverage (exons 6–16) with respect to a deletion recently reported in a large Greek consanguineous family. Haplotype analysis suggested a possible founder effect in the Mediterranean basin. The use of MLPA was therefore crucial in identifying mutated alleles undetected by traditional techniques and in defining the extent of the deletions/duplications. Given the high percentage of identified copy number variations, we suggest that this technique could be used as the initial screening method for molecular diagnosis of Cohen syndrome.
Cohen syndrome; COH1; MLPA
3MC syndrome has been proposed as a unifying term to integrate the overlapping Carnevale, Mingarelli, Malpuech and Michels syndromes. These rare autosomal recessive disorders of unknown cause comprise a spectrum of developmental features including characteristic facial dysmorphism, cleft lip and/or palate, craniosynostosis, learning disability, and genital, limb and vesicorenal anomalies. In a cohort of eleven 3MC families, we identified two mutated genes COLEC11 and MASP1 both of which encode proteins within the lectin complement pathway (CL-K1 and MASP-1 & −3 respectively). CL-K1 is highly expressed in embryonic murine craniofacial cartilage, heart, bronchi, kidney, and vertebral bodies. Zebrafish morphants develop pigment defects and severe craniofacial abnormalities.
Here, we show that CL-K1 serves as a key guidance cue for neural crest cell migration thus demonstrating for the first time, a role for complement pathway factors in fundamental developmental processes and the origin of 3MC syndrome.
Gerodermia osteodysplastica (GO) is an autosomal recessive disorder characterized by wrinkly skin and osteoporosis. Here we demonstrate that GO is caused by loss-of-function mutations in SCYL1BP1, which is expressed at high levels in skin and osteoblasts. The protein localizes to the Golgi apparatus and interacts with Rab6, identifying SCYL1BP1 as a novel golgin. These results associate abnormalities of the secretory pathway with age-related changes in connective tissues.
Noonan syndrome, a developmental disorder characterized by congenital heart defects, reduced growth, facial dysmorphism and variable cognitive deficits, is caused by constitutional dysregulation of the RAS-MAPK signaling pathway. Here we report that germline NRAS mutations conferring enhanced stimulus-dependent MAPK activation account for some cases of this disorder. These findings provide evidence for an obligate dependency on proper NRAS function in human development and growth.
Kabuki syndrome (Niikawa-Kuroki syndrome) is a rare, multiple congenital anomalies/mental retardation syndrome characterized by a peculiar face, short stature, skeletal, visceral and dermatoglyphic abnormalities, cardiac anomalies, and immunological defects. Recently mutations in the histone methyl transferase MLL2 gene have been identified as its underlying cause.
Genomic DNAs were extracted from 62 index patients clinically diagnosed as affected by Kabuki syndrome. Sanger sequencing was performed to analyze the whole coding region of the MLL2 gene including intron-exon junctions. The putative causal and possible functional effect of each nucleotide variant identified was estimated by in silico prediction tools.
We identified 45 patients with MLL2 nucleotide variants. 38 out of the 42 variants were never described before. Consistently with previous reports, the majority are nonsense or frameshift mutations predicted to generate a truncated polypeptide. We also identified 3 indel, 7 missense and 3 splice site.
This study emphasizes the relevance of mutational screening of the MLL2 gene among patients diagnosed with Kabuki syndrome. The identification of a large spectrum of MLL2 mutations possibly offers the opportunity to improve the actual knowledge on the clinical basis of this multiple congenital anomalies/mental retardation syndrome, design functional studies to understand the molecular mechanisms underlying this disease, establish genotype-phenotype correlations and improve clinical management.
Infantile cortical hyperostosis (ICH, OMIM 114000) is a rare familial disorder which affects infants. It spontaneously heals in the first years of life. The disease is characterized by regressive subperiosteal hyperosteogenesis mainly affecting long bones, mandible, clavicles, and ribs which are remarkably swollen and deformed on X-rays. But it is also important to take into consideration the autosomal dominant pattern of inheritance to detect it. In 2005 Gensure et al. detected 3040C→T mutation in COL1A1 gene in three unrelated ICH families. Four generations of patients belonging to the same family were examined in our study. Molecular testing has now disclosed a pathogenic mutation in nine of them. The patients spontaneously recovered. Although our paper shows a distinct correlation between R836C mutation and ICH, there is a certain interindividual and intra-familial variability.
Neonatal and infantile familial disease; COL1A1 gene; Autosomal dominant pattern; Spontaneous recovery
Human ciliopathies are hereditary conditions caused by defects of proteins expressed at the primary cilium. Among ciliopathies, Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS) and nephronophthisis (NPH) present clinical and genetic overlap, being allelic at several loci. One of the most interesting gene is TMEM67, encoding the transmembrane protein meckelin. We performed mutation analysis of TMEM67 in 341 probands, including 265 JSRD representative of all clinical subgroups and 76 MKS fetuses. We identified 33 distinct mutations, of which 20 were novel, in 8/10 (80%) JS with liver involvement (COACH phenotype) and 12/76 (16%) MKS fetuses. No mutations were found in other JSRD subtypes, confirming the strong association between TMEM67 mutations and liver involvement. Literature review of all published TMEM67 mutated cases was performed to delineate genotype-phenotype correlates. In particular, comparison of the types of mutations and their distribution along the gene in lethal versus non lethal phenotypes showed in MKS patients a significant enrichment of missense mutations falling in TMEM67 exons 8 to 15, especially when in combination with a truncating mutation. These exons encode for a region of unknown function in the extracellular domain of meckelin.
TMEM67; MKS3; Joubert syndrome; Meckel syndrome; congenital hepatic fibrosis; COACH syndrome
We used Affymetrix 6.0 GeneChip SNP arrays to characterize copy number variations (CNVs) in a cohort of 70 patients previously characterized on lower-density oligonucleotide arrays affected by idiopathic mental retardation and dysmorphic features. The SNP array platform includes ∼900 000 SNP probes and 900 000 non-SNP oligonucleotide probes at an average distance of 0.7 Kb, which facilitates coverage of the whole genome, including coding and noncoding regions. The high density of probes is critical for detecting small CNVs, but it can lead to data interpretation problems. To reduce the number of false positives, parameters were set to consider only imbalances >75 Kb encompassing at least 80 probe sets. The higher resolution of the SNP array platform confirmed the increased ability to detect small CNVs, although more than 80% of these CNVs overlapped to copy number ‘neutral' polymorphism regions and 4.4% of them did not contain known genes. In our cohort of 70 patients, of the 51 previously evaluated as ‘normal' on the Agilent 44K array, the SNP array platform disclosed six additional CNV changes, including three in three patients, which may be pathogenic. This suggests that about 6% of individuals classified as ‘normal' using the lower-density oligonucleotide array could be found to be affected by a genomic disorder when evaluated with the higher-density microarray platforms.
mental retardation; pathogenic CNVs; SNP array; GeneChip 6.0
Multidimensional impairment of older patients may influence the clinical outcome of diseases. The aim of this study was to evaluate whether a Multidimensional Prognostic Index (MPI) based on a comprehensive geriatric assessment predicts short-term mortality in older patients with heart failure.
Methods and Results
In this prospective study with a 1-month follow-up, 376 patients aged 65 and older with a diagnosis of heart failure were enrolled. A standardized comprehensive geriatric assessment that included information on functional (activities of daily living and instrumental activities of daily living), cognitive (Short Portable Mental Status Questionnaire), and nutritional status (Mini Nutritional Assessment), as well as on risk of pressure sore (Exton-Smith Scale), comorbidities (Cumulative Illness Rating Scale Index), medications, and social support network, was used to calculate the MPI for mortality using a previously validated algorithm. The New York Heart Association, the Enhanced Feedback for Effective Cardiac Treatment, and the Acute Decompensated Heart Failure National Registry regression model scores were also calculated. Higher MPI values were significantly associated with higher 30-day mortality, both in men (MPI-1, 2.8%; MPI-2, 15.3%; MPI-3, 47.4%; P=0.000) and women (MPI-1, 0%; MPI-2, 6.5%; MPI-3, 14.6%; P=0.011). The discrimination of the MPI was also good, with areas under the receiver operating characteristic curves (men: 0.83; 95% CI, 0.75 to 0.90; women: 0.80; 95% CI, 0.71 to 0.89) greater than receiver operating characteristic areas of New York Heart Association (men: 0.63; 95% CI, 0.57 to 0.69; P=0.015; women: 0.65; 95% CI, 0.55 to 0.75; P=0.064), Enhanced Feedback for Effective Cardiac Treatment (men: 0.69; 95% CI, 0.58 to 0.79; P=0.045; women: 0.71; 95% CI, 0.55 to 0.87; P=0.443), and Acute Decompensated Heart Failure National Registry scores (men: 0.65; 95% CI, 0.52 to 0.78; P=0.023; women: 0.67; 95% CI, 0.49 to 0.83, P=0.171).
The MPI, calculated from information collected in a standardized comprehensive geriatric assessment, is useful to estimate the risk of 1-month mortality in older patients with heart failure.
heart failure; mortality; risk factors; Multidimensional Prognostic Index (MPI); prognosis
Acro-cardio-facial syndrome (ACFS) is a rare genetic disorder characterized by split-hand/split-foot malformation (SHFM), facial anomalies, cleft lip/palate, congenital heart defect (CHD), genital anomalies, and mental retardation. Up to now, 9 patients have been described, and most of the reported cases were not surviving the first days or months of age. The spectrum of defects occurring in ACFS is wide, and both interindividual variability and clinical differences among sibs have been reported. The diagnosis is based on clinical criteria, since the genetic mechanism underlying ACFS is still unknown. The differential diagnosis includes other disorders with ectrodactyly, and clefting conditions associated with genital anomalies and heart defects. An autosomal recessive pattern of inheritance has been suggested, based on parental consanguinity and disease's recurrence in sibs in some families. The more appropriate recurrence risk of transmitting the disease for the parents of an affected child seems to be up to one in four. Management of affected patients includes treatment of cardiac, respiratory, and feeding problems by neonatal pediatricians and other specialists. Prognosis of ACFS is poor.
The role of the apoliprotein E (APOE) and the angiotensin converting enzyme (ACE) polymorphisms on health and functional status deterioration in old age is still undefined. Recently, a Multidimensional Prognostic Index (MPI) for 1-year mortality derived from a Comprehensive Geriatric Assessment (CGA) was developed and validated in hospitalized elderly patients. The aim of this study was to investigate the possible association of the APOE and ACE gene polymorphisms with the multidimensional impairment, as evaluated by the MPI, in older patients. These polymorphisms were assessed in 1894 geriatric inpatients divided into three groups according to their MPI values: MPI-1 low risk (n = 988), MPI-2 moderate risk (n = 671), and MPI-3 severe risk of mortality (n = 235). A slight deviation from Hardy–Weinberg equilibrium was observed for the APOE genotypes. With the increasing of the MPI grade, a significant increase in the frequencies of ε4 allele and the ACE D/D genotype was observed. The APOE ε4+ and ACE D/D genotypes were associated with severe MPI grade (APOE ε4+, odds ration [OR] = 1.79, 95% confidence interval [CI] 1.20–2.67; ACE D/D, OR = 1.42, 95% CI 1.05–1.92). The combined APOE ε4+ and ACE D/D genetic status was associated with higher MPI grade (OR = 2.85, 95% CI 1.75–4.65), without interaction. No significant associations between APOE and ACE polymorphisms and 2-year mortality were found. APOE and ACE genes might predispose individuals to health and functional status deterioration in old age, and their effect is additive.
Photoreceptor degeneration is a common feature of ciliopathies, owing to the importance of the highly specialized ciliary structure of these cells. Absence of AHI1, which encodes a cilium-localized protein, has been shown to cause a form of Joubert syndrome highly penetrant for retinal degeneration1,2. We show that Ahi1 knockout mice fail to form outer segments (OS), and show abnormal distribution of opsin throughout photoreceptors. Apoptotic cell death occurs rapidly between 2-4 weeks of age and is significantly delayed by reduced dosage of opsin. This phenotype also displays dosage-sensitive genetic interactions with Nphp1, another ciliopathy gene. Although not a primary cause of retinal blindness in humans, an allele of AHI1 modifies the relative risk of retinal degeneration greater than 7 fold within a nephronophthisis cohort. Our data support context-specific roles for AHI1 as a contributor to retinopathy and may explain a proportion of the variability of retinal phenotypes observed in nephronophthisis.
Multidimensional impairment of older patients may influence the clinical outcome of acute or chronic diseases. Our purpose is to evaluate the usefulness of a multidimensional prognostic index (MPI) based on a comprehensive geriatric assessment (CGA) for predicting mortality risk in older patients with community-acquired pneumonia (CAP).
This prospective study included 134 hospitalized patients aged 65 and older with a diagnosis of CAP. A standardized CGA that included information on clinical, cognitive, functional, and nutritional status as well as comorbidities, medications, and social support network was used to calculate MPI. The pneumonia severity index (PSI) was also calculated. The predictive value of the MPI for all cause mortality over a 1-year follow-up was evaluated and was compared with that of PSI.
Higher MPI values were significantly associated with higher mortality at 30 days (Grade 1 = 3%, Grade 2 = 12%, Grade 3 = 44%, p < .001), 6 months (Grade 1 = 7%, Grade 2 = 21%, Grade 3 = 50%, p < .001), and 1 year (Grade 1 = 10%, Grade 2 = 33%, Grade 3 = 53%, p < .001). A close agreement was found between the estimated mortality by MPI and the observed mortality. MPI had a significant greater discriminatory power than PSI both at 30 days (area under the receiver operating characteristic [ROC] curve = 0.83 vs 0.71, p = .019) and 6 months (0.79 vs 0.69, p = .035), but not after 1 year of follow-up (0.80 vs 0.75, p = .185).
This MPI, calculated from information collected in a standardized CGA, accurately stratifies hospitalized elderly patients with CAP into groups at varying risk of short- and long-term mortality. The predictive accuracy of the MPI was higher than the predictive value of the PSI.
Multidimensional prognostic index; Comprehensive geriatric assessment; Pneumonia; Mortality; Elderly people
The role of the apoliprotein E (APOE) and the angiotensin converting enzyme (ACE) polymorphisms on health and functional status deterioration in old age is still undefined. Recently, a Multidimensional Prognostic Index (MPI) for 1-year mortality derived from a Comprehensive Geriatric Assessment (CGA) was developed and validated in hospitalized elderly patients. The aim of this study was to investigate the possible association of the APOE and ACE gene polymorphisms with the multidimensional impairment, as evaluated by the MPI, in older patients. These polymorphisms were assessed in 1894 geriatric inpatients divided into three groups according to their MPI values: MPI-1 low risk (n = 988), MPI-2 moderate risk (n = 671), and MPI-3 severe risk of mortality (n = 235). A slight deviation from Hardy–Weinberg equilibrium was observed for the APOE genotypes. With the increasing of the MPI grade, a significant increase in the frequencies of ɛ4 allele and the ACE D/D genotype was observed. The APOE ɛ4+ and ACE D/D genotypes were associated with severe MPI grade (APOE ɛ4+, odds ration [OR] = 1.79, 95% confidence interval [CI] 1.20–2.67; ACE D/D, OR = 1.42, 95% CI 1.05–1.92). The combined APOE ɛ4+ and ACE D/D genetic status was associated with higher MPI grade (OR = 2.85, 95% CI 1.75–4.65), without interaction. No significant associations between APOE and ACE polymorphisms and 2-year mortality were found. APOE and ACE genes might predispose individuals to health and functional status deterioration in old age, and their effect is additive.
Joubert syndrome (JS) and related disorders (JSRD) are a group of developmental delay/multiple congenital anomalies syndromes in which the obligatory hallmark is the molar tooth sign (MTS), a complex midbrain-hindbrain malformation visible on brain imaging, first recognized in JS. Estimates of the incidence of JSRD range between 1/80,000 and 1/100,000 live births, although these figures may represent an underestimate. The neurological features of JSRD include hypotonia, ataxia, developmental delay, intellectual disability, abnormal eye movements, and neonatal breathing dysregulation. These may be associated with multiorgan involvement, mainly retinal dystrophy, nephronophthisis, hepatic fibrosis and polydactyly, with both inter- and intra-familial variability. JSRD are classified in six phenotypic subgroups: Pure JS; JS with ocular defect; JS with renal defect; JS with oculorenal defects; JS with hepatic defect; JS with orofaciodigital defects. With the exception of rare X-linked recessive cases, JSRD follow autosomal recessive inheritance and are genetically heterogeneous. Ten causative genes have been identified to date, all encoding for proteins of the primary cilium or the centrosome, making JSRD part of an expanding group of diseases called "ciliopathies". Mutational analysis of causative genes is available in few laboratories worldwide on a diagnostic or research basis. Differential diagnosis must consider in particular the other ciliopathies (such as nephronophthisis and Senior-Loken syndrome), distinct cerebellar and brainstem congenital defects and disorders with cerebro-oculo-renal manifestations. Recurrence risk is 25% in most families, although X-linked inheritance should also be considered. The identification of the molecular defect in couples at risk allows early prenatal genetic testing, whereas fetal brain neuroimaging may remain uninformative until the end of the second trimester of pregnancy. Detection of the MTS should be followed by a diagnostic protocol to assess multiorgan involvement. Optimal management requires a multidisciplinary approach, with particular attention to respiratory and feeding problems in neonates and infants. Cognitive and behavioral assessments are also recommended to provide young patients with adequate neuropsychological support and rehabilitation. After the first months of life, global prognosis varies considerably among JSRD subgroups, depending on the extent and severity of organ involvement.
Aim of this study was to evaluate the usefulness of a Multidimensional Prognostic Index (MPI) based on a Comprehensive Geriatric Assessment (CGA) for predicting mortality risk in older patients with dementia. The present was a retrospective study with a year of follow-up that included 262 patients aged 65 years and older with a diagnosis of dementia. A standardized CGA that included information on clinical, cognitive, functional, and nutritional aspects, as well as comorbidity, medications, and social support network, was used to calculate MPI. The predictive value of the MPI for all-cause mortality over 1 month, 6 months, and 12 months of follow-up was evaluated. Higher MPI values were significantly associated with higher mortality at 1 month (MPI-1, low risk = 0%, MPI-2, moderate risk = 5.2%, MPI-3, severe risk = 13.7%; p < 0.002), 6-months (MPI-1 = 2.7%, MPI-2 = 11.2%, MPI-3 = 28.8%; p < 0.001), and 12-months (MPI-1 = 2.7%, MPI-2 = 18.2%, MPI-3 = 35.6%; p < 0.001) of follow-up. The discrimination of the MPI was also good, with areas under the ROC curves of 0.77 (sensitivity = 82.9%, specificity = 66.0%, with a cut off value > 0.16) at 12-months of follow up. In conclusion, the MPI, calculated from information collected in a standardized CGA, accurately stratified hospitalized elderly patients with dementia into groups at varying risk of short- and long-term mortality.
Comprehensive Geriatric Assessment (CGA); dementia; mortality; Multidimensional Prognostic Index (MPI); prognosis; survival
N-myristoylation is a common form of co-translational protein fatty acylation resulting from the attachment of myristate to a required N-terminal glycine residue.1,2 We show that aberrantly acquired N-myristoylation of SHOC2, a leucine-rich repeat-containing protein that positively modulates RAS-MAPK signal flow,3–6 underlies a clinically distinctive condition of the neuro-cardio-facial-cutaneous disorders family. Twenty-five subjects with a relatively consistent phenotype previously termed Noonan-like syndrome with loose anagen hair [OMIM 607721]7 shared the 4A>G missense change (Ser2Gly) in SHOC2 that introduces an N-myristoylation site, resulting in aberrant targeting of SHOC2 to the plasma membrane and impaired translocation to the nucleus upon growth factor stimulation. Expression of SHOC2S2G
in vitro enhanced MAPK activation in a cell type-specific fashion. Induction of SHOC2S2G in Caenorhabditis elegans engendered protruding vulva, a neomorphic phenotype previously associated with aberrant signaling. These results document the first example of an acquired N-terminal lipid modification of a protein causing human disease.