Crohn disease is a chronic, inflammatory disease of the gastrointestinal tract. A locus of ∼250 kb at 5q31 (IBD5) 1,2 was previously associated with susceptibility to Crohn disease, as indicated by increased prevalence of a risk haplotype of 11 single-nucleotide polymorphisms 3 among individuals with Crohn disease, but the pathogenic lesion in the region has not yet been identified. We report here that two variants in the organic cation transporter cluster at 5q31 (a missense substitution in SLC22A4 and a G→C transversion in the SLC22A5 promoter) form a haplotype associated with susceptibility to Crohn disease. These variants alter transcription and transporter functions of the organic cation transporters and interact with variants in another gene associated with Crohn disease, CARD15, to increase risk of Crohn disease. These results suggest that SLC22A4, SLC22A5 and CARD15 act in a common pathogenic pathway to cause Crohn disease.By resequencing the five genes in the IBD5 interval, we identified ten new single-nucleotide polymorphisms (SNPs; Supplementary Table 1 online), including two in the organic cation transporter (OCTN) gene cluster (SLC22A4 and SLC22A5, encoding OCTN1 and OCTN2, respectively) that are predicted to have functional effects. The first is a C→T substitution in SLC22A4 exon 9 (1672C→T; numbered according to the cDNA sequence for SLC22A4 in GenBank) that causes the amino acid substitution L503F. Leucine or isoleucine is conserved at this position in most OCTNs and other related transporters 4 (Fig. 1a), and its substitution with phenylalanine is predicted computationally (by PolyPhen 5 , TMHMM2 (ref. 6) and PHAT transmembrane database 7 ) to be nonconservative. The second SNP is a G→C transversion in the SLC22A5 promoter (-207G→C), which disrupts a heat shock element (HSE) 207 bp upstream of the start codon (Fig. 1b).1672C→T and -207G→C are in strong linkage disequilibrium and create a two-allele risk haplotype (TC) enriched in individuals with Crohn disease (frequency = 0.54 in affected individuals versus 0.42 in controls, P = 0.0003;

Noonan syndrome (NS) is a relatively common genetic disorder, characterized by typical facies, short stature, developmental delay, and cardiac abnormalities. Known causative genes account for 70-80% of clinically diagnosed NS patients, but the genetic basis for the remaining 20-30% of cases is unknown. We performed nextgeneration sequencing on germ-line DNA from 27 NS patients lacking a mutation in the known NS genes. We identified gainof-function alleles in Ras-like without CAAX 1 (RIT1) and mitogenactivated protein kinase kinase 1 (MAP2K1) and previously unseen loss-of-function variants in RAS p21 protein activator 2 (RASA2) that are likely to cause NS in these patients. Expression of the mutant RASA2, MAP2K1, or RIT1 alleles in heterologous cells increased RAS-ERK pathway activation, supporting a causative role in NS pathogenesis. Two patients had more than one disease-associated variant. Moreover, the diagnosis of an individual initially thought to have NS was revised to neurofibromatosis type 1 based on an NF1 nonsense mutation detected in this patient. Another patient harbored a missense mutation in NF1 that resulted in decreased protein stability and impaired ability to suppress RAS-ERK activation; however, this patient continues to exhibit a NS-like phenotype. In addition, a nonsense mutation in RPS6KA3 was found in one patient initially diagnosed with NS whose diagnosis was later revised to Coffin-Lowry syndrome. Finally, we identified other potential candidates for new NS genes, as well as potential carrier alleles for unrelated syndromes. Taken together, our data suggest that nextgeneration sequencing can provide a useful adjunct to RASopathy diagnosis and emphasize that the standard clinical categories for RASopathies might not be adequate to describe all patients.human genetics | developmental diseases | whole exome sequencing | PTPN11 | RAS

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