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1.  Deep Dermatophytosis and Inherited CARD9 Deficiency 
The New England journal of medicine  2013;369(18):1704-1714.
Deep dermatophytosis is a severe and sometimes life-threatening fungal infection caused by dermatophytes. It is characterized by extensive dermal and subcutaneous tissue invasion and by frequent dissemination to the lymph nodes and, occasionally, the central nervous system. The condition is different from common superficial dermatophyte infection and has been reported in patients with no known immunodeficiency. Patients are mostly from North African, consanguineous, multiplex families, which strongly suggests a mendelian genetic cause.
We studied the clinical features of deep dermatophytosis in 17 patients with no known immunodeficiency from eight unrelated Tunisian, Algerian, and Moroccan families. Because CARD9 (caspase recruitment domain–containing protein 9) deficiency has been reported in an Iranian family with invasive fungal infections, we also sequenced CARD9 in the patients.
Four patients died, at 28, 29, 37, and 39 years of age, with clinically active deep dermatophytosis. No other severe infections, fungal or otherwise, were reported in the surviving patients, who ranged in age from 37 to 75 years. The 15 Algerian and Tunisian patients, from seven unrelated families, had a homozygous Q289X CARD9 allele, due to a founder effect. The 2 Moroccan siblings were homozygous for the R101C CARD9 allele. Both alleles are rare deleterious variants. The familial segregation of these alleles was consistent with autosomal recessive inheritance and complete clinical penetrance.
All the patients with deep dermatophytosis had autosomal recessive CARD9 deficiency. Deep dermatophytosis appears to be an important clinical manifestation of CARD9 deficiency. (Funded by Agence Nationale pour la Recherche and others.)
PMCID: PMC4084693  PMID: 24131138
2.  Inflammatory Bowel Disease and Mutations Affecting the Interleukin-10 Receptor 
The New England journal of medicine  2009;361(21):2033-2045.
The molecular cause of inflammatory bowel disease is largely unknown.
We performed genetic-linkage analysis and candidate-gene sequencing on samples from two unrelated consanguineous families with children who were affected by early-onset inflammatory bowel disease. We screened six additional patients with early-onset colitis for mutations in two candidate genes and carried out functional assays in patients’ peripheral-blood mononuclear cells. We performed an allogeneic hematopoietic stem-cell transplantation in one patient.
In four of nine patients with early-onset colitis, we identified three distinct homozygous mutations in genes IL10RA and IL10RB, encoding the IL10R1 and IL10R2 proteins, respectively, which form a heterotetramer to make up the interleukin-10 receptor. The mutations abrogate interleukin-10–induced signaling, as shown by deficient STAT3 (signal transducer and activator of transcription 3) phosphorylation on stimulation with interleukin-10. Consistent with this observation was the increased secretion of tumor necrosis factor α and other proinflammatory cytokines from peripheral-blood mononuclear cells from patients who were deficient in IL10R subunit proteins, suggesting that interleukin-10–dependent “negative feedback” regulation is disrupted in these cells. The allogeneic stem-cell transplantation performed in one patient was successful.
Mutations in genes encoding the IL10R subunit proteins were found in patients with early-onset enterocolitis, involving hyperinflammatory immune responses in the intestine. Allogeneic stem-cell transplantation resulted in disease remission in one patient.
PMCID: PMC2787406  PMID: 19890111
3.  A Homozygous CARD9 Mutation in a Family with Susceptibility to Fungal Infections 
The New England journal of medicine  2009;361(18):1727-1735.
Chronic mucocutaneous candidiasis may be manifested as a primary immunodeficiency characterized by persistent or recurrent infections of the mucosa or the skin with candida species. Most cases are sporadic, but both autosomal dominant inheritance and autosomal recessive inheritance have been described.
We performed genetic studies in 36 members of a large, consanguineous five-generation family, in which 4 members had recurrent fungal infections and an additional 3 members died during adolescence, 2 after invasive infection of the brain with candida species. All 36 family members were enrolled in the study, and 22 had blood samples taken for DNA analysis. Homozygosity mapping was used to locate the mutated gene. In the 4 affected family members (patients) and the 18 unaffected members we sequenced CARD9, the gene encoding the caspase recruitment domain-containing protein 9, carried out T-cell phenotyping, and performed functional studies, with the use of either leukocytes from the patients or a reconstituted murine model of the genetic defect.
We found linkage (lod score, 3.6) to a genomic interval on chromosome 9q, including CARD9. All four patients had a homozygous point mutation in CARD9, resulting in a premature termination codon (Q295X). Healthy family members had wild-type expression of the CARD9 protein; the four patients lacked wild-type expression, which was associated with low numbers of Th17 cells (helper T cells producing interleukin-17). Functional studies based on genetic reconstitution of myeloid cells from Card9−/− mice showed that the Q295X mutation impairs innate signaling from the antifungal pattern-recognition receptor dectin-1.
An autosomal recessive form of susceptibility to chronic mucocutaneous candidiasis is associated with homozygous mutations in CARD9.
PMCID: PMC2793117  PMID: 19864672
4.  A novel syndrome with congenital neutropenia caused by mutations in G6PC3 
Severe congenital neutropenia (SCN) is characterized by early onset of severe bacterial infections due to a paucity of mature neutrophils. There is also an increased risk of leukemia. The genetic causes of SCN are unknown in many patients.
Genome-wide genotyping and linkage analysis were performed on two consanguineous pedigrees with a total of five children affected with SCN. Candidate genes from the linkage interval were sequenced. Functional assays and reconstitution experiments were carried out.
All index patients had susceptibility to bacterial infections and myeloid maturation arrest in the bone marrow; some had structural heart defects and venous angiectasia on the trunk and extremities. Linkage analysis of the two index families yielded a combined multipoint LOD score of 5.74 on a linkage interval on chromosome 17q21. Sequencing of the candidate gene glucose-6-phosphatase catalytic subunit 3 (G6PC3) revealed a homozygous missense mutation in exon 6 in all affected children in the two families, abrogating enzymatic activity of Glucose-6-phosphatase. Neutrophils and fibroblasts of patients had increased susceptibility to apoptosis. Myeloid cells showed evidence of increased endoplasmic reticulum stress and increased activity of GSK3β. We identified seven additional, unrelated SCN patients with syndromic features and distinct biallelic mutations in G6PC3.
Defective function of G6PC3 defines a novel SCN syndrome associated with cardiac and urogenital malformations.
PMCID: PMC2778311  PMID: 19118303

Results 1-4 (4)