Fifty to eighty percent of autosomal recessive congenital severe to profound hearing impairment result from mutations in a single gene, GJB2, that encodes the protein connexin 26. One mutation of this gene, the 35delG allele, is particularly common in white populations. We report evidence that the high frequency of this allelic variant is the result of a founder eVect rather than a mutational hot spot in GJB2, which was the prevailing hypothesis. Patients homozygous for the 35delG mutation and normal hearing controls originating from Belgium, the UK, and the USA were genotyped for diVerent single nucleotide polymorphisms (SNPs). Four SNPs mapped in the immediate vicinity of GJB2, while two were positioned up to 76 kb from it. Significant diVerences between the genotypes of patients and controls for the five SNPs closest to GJB2 were found, with nearly complete association of one SNP allele with the 35delG mutation. For the most remote SNP, we could not detect any association. We conclude that the 35delG mutation is derived from a common, albeit ancient founder. (J Med Genet 2001;38:515-518)

Fanconi anemia (FA) is a rare genetic syndrome characterized by progressive bone marrow failure (BMF), congenital anomalies, and a predisposition to malignancy. Successful gene transfer into hematopoietic stem cells (HSCs) could reverse BMF in this disease. We developed clinical trials to determine whether a sufficient number of CD34(+) stem cells could be collected for gene modification and to evaluate the safety and efficacy of HSC-corrective gene transfer in FA genotype A (FANCA) patients. Here, we report that FA patients have significant depletion of their BM CD34(+) cell compartment even before severe pancytopenia is present. However, oncoretroviral-mediated ex vivo gene transfer was efficient in clinical scale in FA-A cells, leading to reversal of the cellular phenotype in a significant percentage of CD34(+) cells. Re-infusion of gene-corrected products in two patients was safe and well tolerated and accompanied by transient improvements in hemoglobin and platelet counts. Gene correction was transient, likely owing to the low dose of gene-corrected cells infused. Our early experience shows that stem cell collection is well tolerated in FA patients and suggests that collection be considered as early as possible in patients who are potential candidates for future gene transfer trials.

We have evaluated in detail children and adults with FA for their growth and endocrine function. Overall, 79% of children and adults with FA had one or more endocrine abnormality.

Summary Fanconi anaemia is an autosomal recessive or X-linked disease characterized by progressive bone marrow failure, variable congenital abnormalities and a predisposition to malignancy. Reports of immune function in this population are limited, and include only specific areas of immune performance, showing variable defects. We report a cross-sectional immunological assessment in 10 children with FA. Absolute numbers of B cells and natural killer (NK) cells were reduced compared to controls (P = 0·048 and P = 0·0002, respectively), while absolute number of T cells were within normal range. Perforin and granzyme content of NK cells was reduced (P < 0·00001 and P = 0·0057, respectively) along with the NK cell cytotoxicity (P < 0·001). Antigen proliferation in response to tetanus was decreased (P = 0·008) while responses to candida and phytohaemagglutinin were not. Cytotoxic T cell function was also reduced (P < 0·0001). Immunoglobulin G levels were normal in those evaluated. Our series represents the first attempt at a comprehensive quantitative and functional evaluation of immune function in this rare group of patients and demonstrates a significant deficit in the NK cell compartment, a novel quantitative B cell defect, along with abnormal cytotoxic function. These findings may be especially relevant in this patient population with known predisposition to DNA damage and malignancy.

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Abnormalities in glucose metabolism are frequent in young FA patients without prior diagnosis of diabetes, and are associated with marked defects in insulin secretion.

Background Fanconi Anemia (FA) is a rare genetic disorder resulting in a loss of function of the FA-related DNA repair pathway. Individuals with FA are predisposed to some cancers including oropharyngeal and gynecological cancers with known associations with human papillomavirus (HPV) in the general population. Since individuals with FA respond poorly to chemotherapy and radiation, prevention of cancer is critical. Methods To determine if individuals with FA are particularly susceptible to oral HPV infection, we analyzed survey-based risk factor data and tested DNA isolated from oral rinses from 126 individuals with FA and 162 unaffected first-degree family members for 37 HPV types. Results Fourteen individuals (11.1%) with FA tested positive, significantly more (p=0.003) than family members (2.5%). While HPV prevalence was even higher for sexually active individuals with FA (17.7% vs. 2.4% in family; p=0.003), HPV positivity also tended to be higher in the sexually inactive (8.7% in FA vs. 2.9% in siblings). Indeed, having FA increased HPV positivity 4.9 fold (95%CI: 1.6–15.4) considering age and sexual experience, but did not differ by other potential risk factors. Conclusion Our studies suggest that oral HPV is more common in individuals with FA. It will be essential to continue to explore associations between risk factors and immune dysfunction on HPV incidence and persistence over time. Impact HPV vaccination should be emphasized in those with FA as a first step to prevent oropharyngeal cancers, although additional studies are needed to determine if the level of protection it offers in this population is adequate.