A Homozygous Nonsense Mutation in the Zinc-Finger Domain of the Human Hairless Gene Underlies Congenital Atrichia

To the Editor: Congenital atrichia (OMIM 209500) is a rare form of total alopecia and is inherited in an autosomal recessive pattern (Burke, 1954Burke G. Uber atrichia congenita und ihren erbgang.Arch Dermatol Syphilis. 1954; 197: 322-343Crossref Scopus (9) Google Scholar;Landes and Langer, 1956Landes E. Langer I. Ein beitrag zur hypotrichosis congenita.Hautzart. 1956; 7: 413-415PubMed Google Scholar;Ahmad et al., 1993Ahmad M. Abbas H. ul Haque S. Alopecia universalis as a single abnormality in an inbred Pakistani kindred.Am J Med Genet. 1993; 46: 369-371Crossref PubMed Scopus (26) Google Scholar,Ahmad et al., 1998aAhmad W. ul Haque M.F. Brancolini V. et al.Alopecia universalis associated with a mutation in the human hairless gene.Science. 1998; 279: 720-724Crossref PubMed Scopus (357) Google Scholar,Ahmad et al., 1998bAhmad W. Irvine A.D. Lam H. et al.A missense mutation in the zinc-finger domain of the human hairless gene underlies congenital atrichia in a family of Irish travelers.Am J Hum Genet. 1998; 63: 984-991Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar,Ahmad et al., 1999Ahmad W. Zlotogorski A. Panteleyev A.A. et al.Genomic organization of the human hairless gene and identification of a mutation underlying congenital atrichia in an Arab Palestinian family.Genomics. 1999; 56: 141-148Crossref PubMed Scopus (82) Google Scholar;Zlotogorski et al., 1998Zlotogorski A. Ahmad W. Christiano A.M. Congenital atrichia in five Arab Palestinian families resulting from a deletion mutation in the human hairless gene.Hum Genet. 1998; 103: 400-404Crossref PubMed Scopus (70) Google Scholar). In individuals affected with this form of hair loss, hairs are typically absent from the scalp, and patients are almost completely devoid of eyebrows, eyelashes, axillary, and pubic hair. A scalp skin biopsy from affected individuals typically reveals the absence of mature hair follicle structures. Variations in the structure and shape of hair follicle remnants have been reported in patients with congenital atrichia. These include shortened hair follicles containing horny plugs, and a reduced number of pilosebaceous units containing malformed hairs without cuticles (Porter, 1973Porter P.S. Genetic disorders of hair growth.J Invest Dermatol. 1973; 60: 493-502Abstract Full Text PDF PubMed Scopus (12) Google Scholar). Affected individuals show no growth or developmental delay, have normal hearing, teeth, and nails, and no abnormalities in sweating. Congenital atrichia affects males and females equally, from all ethnic backgrounds. We and colleagues (Ahmad et al., 1998aAhmad W. ul Haque M.F. Brancolini V. et al.Alopecia universalis associated with a mutation in the human hairless gene.Science. 1998; 279: 720-724Crossref PubMed Scopus (357) Google Scholar;Nothen et al., 1998Nothen M.M. Cichon S. Vogt I.R. et al.A gene for autosomal congenital alopecia maps to chromosome 8p21–22.Am J Hum Genet. 1998; 62: 386-390Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar) recently reported a linkage in this form of atrichia to chromosome 8p12, and we identified the human homolog of the hairless gene in the same region of chromosome 8 (Ahmad et al., 1998aAhmad W. ul Haque M.F. Brancolini V. et al.Alopecia universalis associated with a mutation in the human hairless gene.Science. 1998; 279: 720-724Crossref PubMed Scopus (357) Google Scholar). More recently, we have identified pathogenic missense and deletion mutations in the human hairless gene in this form of atrichia in families from Pakistan, Ireland, and Israel (Ahmad et al., 1998aAhmad W. ul Haque M.F. Brancolini V. et al.Alopecia universalis associated with a mutation in the human hairless gene.Science. 1998; 279: 720-724Crossref PubMed Scopus (357) Google Scholar,Ahmad et al., 1998bAhmad W. Irvine A.D. Lam H. et al.A missense mutation in the zinc-finger domain of the human hairless gene underlies congenital atrichia in a family of Irish travelers.Am J Hum Genet. 1998; 63: 984-991Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar,Ahmad et al., 1999Ahmad W. Zlotogorski A. Panteleyev A.A. et al.Genomic organization of the human hairless gene and identification of a mutation underlying congenital atrichia in an Arab Palestinian family.Genomics. 1999; 56: 141-148Crossref PubMed Scopus (82) Google Scholar;Zlotogorski et al., 1998Zlotogorski A. Ahmad W. Christiano A.M. Congenital atrichia in five Arab Palestinian families resulting from a deletion mutation in the human hairless gene.Hum Genet. 1998; 103: 400-404Crossref PubMed Scopus (70) Google Scholar). As an extension of these studies, here we studied a family from Japan with a single member affected with congenital atrichia, whose clinical history was described in detail earlier byNomura and Hashimoto, 1998Nomura K. Hashimoto I. Atrichia with papular lesions: successful genetic counselling about having a child.Br J Dermatol. 1998; 139: 742-743Crossref PubMed Scopus (4) Google Scholar. Briefly, the proband was born with normal hair, which began to shed at the age of 6 mo and progressed to complete hairlessness at the age of 1 y. Hair was absent from the scalp, axillae, pubis, and other parts of the body, and eyebrows and eyelashes were sparse. She had the additional characteristics features of grouped cystic and papular lesions on the neck, buttocks, and thighs. A skin biopsy from the neck showed deep dermal keratinous cysts. The patient exhibited no other physical, developmental, or neuropsychologic abnormality. The family pedigree is strongly suggestive of autosomal recessive inheritance (Figure 1a). To search for an underlying mutation in the hairless gene, genomic DNA was isolated from peripheral blood collected in EDTA-containing tubes according to standard techniques (Sambrook et al., 1989Sambrook J. Fritsch E.G. Maniatis T. Molecular Cloning: a Laboratory Manual. 2nd edn. Cold Spring Harbor, New York1989Google Scholar). Exons and splice junctions were polymerase chain reaction amplified from genomic DNA and sequenced directly in an ABI Prism 310 Automated Sequencer, using the ABI Prism Rhodamine Terminator Cycle Sequencing Ready Reaction Sequencing Kit (PE Applied Biosystems, Foster City, CA), following purification in a Centriflex Gel Filtration Cartridge (Edge Biosystems, Gaithersburg, MD). A 287 bp polymerase chain reaction fragment containing exon 6 of the human hairless gene was amplified using primers described earlier (Ahmad et al., 1998bAhmad W. Irvine A.D. Lam H. et al.A missense mutation in the zinc-finger domain of the human hairless gene underlies congenital atrichia in a family of Irish travelers.Am J Hum Genet. 1998; 63: 984-991Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). Sequence analysis of exon 6 revealed a C-to-T transition at nucleotide position 1837 (Figure 1b), resulting in the conversion of an arginine to a premature termination codon, designated R613X. This mutation is predicted to result in the absence of mRNA and functional protein, due to nonsense-mediated mRNA decay (Maquat, 1996Maquat L.E. Defects in RNA splicing and the consequence of shortened translational reading frames.Am J Hum Genet. 1996; 59: 284-288Google Scholar). Recently, we have reported missense and deletion mutations in the human hairless gene in families from Pakistan, Ireland, and Israel with congenital atrichia (Ahmad et al., 1998aAhmad W. ul Haque M.F. Brancolini V. et al.Alopecia universalis associated with a mutation in the human hairless gene.Science. 1998; 279: 720-724Crossref PubMed Scopus (357) Google Scholar,Ahmad et al., 1998bAhmad W. Irvine A.D. Lam H. et al.A missense mutation in the zinc-finger domain of the human hairless gene underlies congenital atrichia in a family of Irish travelers.Am J Hum Genet. 1998; 63: 984-991Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar;Zlotogorski et al., 1998Zlotogorski A. Ahmad W. Christiano A.M. Congenital atrichia in five Arab Palestinian families resulting from a deletion mutation in the human hairless gene.Hum Genet. 1998; 103: 400-404Crossref PubMed Scopus (70) Google Scholar;Ahmad et al., 1999Ahmad W. Zlotogorski A. Panteleyev A.A. et al.Genomic organization of the human hairless gene and identification of a mutation underlying congenital atrichia in an Arab Palestinian family.Genomics. 1999; 56: 141-148Crossref PubMed Scopus (82) Google Scholar). In this study, we report the identification of a nonsense mutation in the highly conserved zinc-finger DNA binding domain of the gene in a family from Japan. In our previous study, we reported a missense mutation (R620Q) in the zinc-finger domain of the hairless gene in a large family of Irish travellers from Ireland (Ahmad et al., 1998bAhmad W. Irvine A.D. Lam H. et al.A missense mutation in the zinc-finger domain of the human hairless gene underlies congenital atrichia in a family of Irish travelers.Am J Hum Genet. 1998; 63: 984-991Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar), suggesting that mutations tend to cluster in the zinc-finger domain of the gene, as shown in our analysis of hairless and rhino mouse mutations (Ahmad et al., 1998cAhmad W. Panteleyev A. Sundberg J.P. Christiano A.M. Molecular basis for the rhino (hr rh8J) phenotype: a nonsense mutation in the mouse hairless gene.Genomics. 1998; 53: 383-386Crossref PubMed Scopus (48) Google Scholar,Ahmad et al., 1998dAhmad W. Panteleyev A. Henson-Apollonio V. Sundberg J.P. Christiano A.M. Molecular basis of a novel rhino (hr rhChr) phenotype: a nonsense mutation in the mouse hairless gene.Exp Dermatol. 1998; 7: 281-288PubMed Google Scholar;Panteleyev et al., 1998aPanteleyev A.A. Ahmad W. Malashenko A.M. et al.Molecular basis for the rhino Yurlovo (hr rhY) phenotype: severe skin abnormalities and female reproductive defects associated with an insertion in the hairless gene.Exp Dermatol. 1998; 7: 281-288Crossref PubMed Scopus (46) Google Scholar). The phenotypic appearance of the proband in this family is reminiscent of our previous cases, as well as those reported earlier (Burke, 1954Burke G. Uber atrichia congenita und ihren erbgang.Arch Dermatol Syphilis. 1954; 197: 322-343Crossref Scopus (9) Google Scholar;Landes and Langer, 1956Landes E. Langer I. Ein beitrag zur hypotrichosis congenita.Hautzart. 1956; 7: 413-415PubMed Google Scholar;Cantu et al., 1980Cantu J.M. Sanchez-Corona J. Gonzalez-Mendoza A. et al.Autosomal recessive inheritance of atrichia congenita.Clin Genet. 1980; 17: 209-212Crossref PubMed Scopus (17) Google Scholar), including atrichia with cystic papules on the elbows and knees. As early as 1954, this rare human disease was named atrichia with papular lesions, and was characterized as normal hair formation at birth followed by hair loss associated with the formation of comedones and follicular cysts (Damste and Prakken, 1954Damste J. Prakken J.R. Atrichia with papular lesions: a variant of congenital ectodermal dysplasias.Dermatologica. 1954; 108: 114-117Crossref PubMed Google Scholar;Landes and Langer, 1956Landes E. Langer I. Ein beitrag zur hypotrichosis congenita.Hautzart. 1956; 7: 413-415PubMed Google Scholar;Lowenthal and Prakken, 1961Lowenthal L.J.A. Prakken J.R. Atrichia with papular lesions.Dermatologica. 1961; 122: 85-87Crossref PubMed Scopus (39) Google Scholar;Del Castillo et al., 1974Del Castillo V. Ruiz-Maldonado R. Carnevale A. Atrichia with papular lesions and mental retardation in two sisters.Int J Dermatol. 1974; 13: 261-265Crossref PubMed Scopus (32) Google Scholar;Cantu et al., 1980Cantu J.M. Sanchez-Corona J. Gonzalez-Mendoza A. et al.Autosomal recessive inheritance of atrichia congenita.Clin Genet. 1980; 17: 209-212Crossref PubMed Scopus (17) Google Scholar;Kanzler and Rasmussen, 1986Kanzler M.H. Rasmussen J.E. Atrichia with papular lesions.Arch Dermatol. 1986; 122: 565-567Crossref PubMed Scopus (31) Google Scholar;Rook and Dawber, 1991Rook A. Dawber R. Diseases of the Hair and Scalp. 2nd edn. Blackwell, Oxford1991: 187-197Google Scholar;Misciali et al., 1992Misciali C. Tosti A. Fanti P.A. Borrello P. Piraccini B.M. Atrichia and papular lesions: report of a case.Dermatologica. 1992; 185: 284-288Crossref Scopus (21) Google Scholar). In 1989, the human disease was first proposed as a homolog of the hairless mouse mutation (Sundberg et al., 1989Sundberg J.P. Dunstan R.W. Compton J.G. Hairless mouse, HRS/J hr/hr.in: Jones T.C. Mohr U. Hunt R.D. Monographs on Pathology of Laboratory Animals Integument and Mammary Glands. Springer-Verlag, 1989: 192-197Crossref Google Scholar). The molecular basis of the hairless mouse phenotype was previously found to be the result of a murine leukemia proviral insertion in intron 6 of the hairless gene, reported to result in aberrant splicing (Cachon-Gonzalez et al., 1994Cachon-Gonzalez M.B. Fenner S. Coffin J.M. et al.Structure and expression of the hairless gene of mice.Proc Natl Acad Sci USA. 1994; 91: 7717-7772Crossref PubMed Scopus (164) Google Scholar). In addition, we recently reported a series of nonsense and deletion mutations in the hairless mice gene in the rhino mice, which were known to be allelic to hairless mice (Ahmad et al., 1998cAhmad W. Panteleyev A. Sundberg J.P. Christiano A.M. Molecular basis for the rhino (hr rh8J) phenotype: a nonsense mutation in the mouse hairless gene.Genomics. 1998; 53: 383-386Crossref PubMed Scopus (48) Google Scholar,Ahmad et al., 1998dAhmad W. Panteleyev A. Henson-Apollonio V. Sundberg J.P. Christiano A.M. Molecular basis of a novel rhino (hr rhChr) phenotype: a nonsense mutation in the mouse hairless gene.Exp Dermatol. 1998; 7: 281-288PubMed Google Scholar;Panteleyev et al., 1998aPanteleyev A.A. Ahmad W. Malashenko A.M. et al.Molecular basis for the rhino Yurlovo (hr rhY) phenotype: severe skin abnormalities and female reproductive defects associated with an insertion in the hairless gene.Exp Dermatol. 1998; 7: 281-288Crossref PubMed Scopus (46) Google Scholar). The hairless protein is a putative transcription factor with a single zinc-finger domain, which is highly expressed in the brain and the skin. The hairless gene contains a single zinc-finger DNA binding domain with a novel spacing of a conserved six-cysteine motif, and only weak homology to two classes of genes: TSGA, a testes-specific transcription factor, and TRIPs, thyroid hormone interacting proteins (Ahmad et al., 1999Ahmad W. Zlotogorski A. Panteleyev A.A. et al.Genomic organization of the human hairless gene and identification of a mutation underlying congenital atrichia in an Arab Palestinian family.Genomics. 1999; 56: 141-148Crossref PubMed Scopus (82) Google Scholar). Despite the high levels of hairless expression in the brain as compared with skin, neither hairless nor rhino mice display any neurologic, behavioral, or developmental defects whatsoever. This finding correlates well with human patients with atrichia, in whom we have also never observed these sequelae. We have, however, observed a striking genotype–phenotype relationship between hairless and rhino mice with respect to the severity of the disease phenotype in the hair and skin. The hairless proviral insertion mutation results in a moderate hairless phenotype; however, the nonsense and deletion mutations in rhino mice result in a much more profound and accelerated phenotype (Ahmad et al., 1998cAhmad W. Panteleyev A. Sundberg J.P. Christiano A.M. Molecular basis for the rhino (hr rh8J) phenotype: a nonsense mutation in the mouse hairless gene.Genomics. 1998; 53: 383-386Crossref PubMed Scopus (48) Google Scholar,Ahmad et al., 1998dAhmad W. Panteleyev A. Henson-Apollonio V. Sundberg J.P. Christiano A.M. Molecular basis of a novel rhino (hr rhChr) phenotype: a nonsense mutation in the mouse hairless gene.Exp Dermatol. 1998; 7: 281-288PubMed Google Scholar;Panteleyev et al., 1998aPanteleyev A.A. Ahmad W. Malashenko A.M. et al.Molecular basis for the rhino Yurlovo (hr rhY) phenotype: severe skin abnormalities and female reproductive defects associated with an insertion in the hairless gene.Exp Dermatol. 1998; 7: 281-288Crossref PubMed Scopus (46) Google Scholar). Surprisingly, we have not observed this genotype-phenotype relationship in our human patients with atrichia. We have identified two missense and two deletion mutations thus far, with indistinguishable clinical findings. The Japanese patient in this study represents the first nonsense mutation in the hairless gene in an atrichia patient, and similar to the earlier reports, the phenotype is identical. Why we observe a marked genotype–phenotype correlation in mice but not humans with atrichia is currently under investigation. The precise function of hairless protein remains elusive; however, recent studies have established that hairless functions as a transcriptional corepressor in the brain, and is regulated directly by thyroid hormone (Thompson, 1996Thompson C.C. Thyroid hormone-responsive genes in developing cerebellum include a novel synaptogamin and a hairless homolog.J Neuroscience. 1996; 16: 7832-7840PubMed Google Scholar;Thompson and Bottcher, 1996Thompson C.C. Bottcher M.C. The product of a thyroid hormone-responsive gene interacts with thyroid hormone receptors.Proc Natl Acad Sci USA. 1996; 94: 8527-8532Crossref Scopus (124) Google Scholar). In the hair follicle, it appears to function in the cellular transition to the first adult hair cycle, and in its absence hair growth completely ceases, a new hair is never induced, and the result is a complete form of inherited alopecia. The hair matrix cells undergo a premature and massive apoptosis, together with a concomitant decline in Bcl-2 expression, a loss of NCAM positivity, and a disconnection with the overlying epithelial sheath essential for the movement of the dermal papilla (Panteleyev et al., 1998bPanteleyev A.A. van der Veen C. Rosenbach T. et al.Towards defining the pathogenesis of the hairless phenotype.J Invest Dermatol. 1998; 110: 903-907Abstract Full Text Full Text PDF Scopus (79) Google Scholar,Panteleyev et al., 1998cPanteleyev A.A. Botchkareva N.V. van der Veen C. Christiano A.M. Paus R. Pathobiology of the the hairless phenotype: Dysregulation of hair follicle apoptosis and topobiology during the initiation of follicle cycling.J Invest Dermatol. 1998; 110: 577Google Scholar). As a consequence, the hair bulb and dermal papilla remain stranded in the dermis, and indispensable messages between the dermal papilla and stem cells in the bulge are not transmitted, thus no further hair growth occurs. In hairless mice and humans with congenital atrichia, we postulate that the absence of hairless protein initiates a premature and abnormal catagen due to abnormal signaling that normally control catagen-associated hair follicle remodeling (Panteleyev et al., 1998cPanteleyev A.A. Botchkareva N.V. van der Veen C. Christiano A.M. Paus R. Pathobiology of the the hairless phenotype: Dysregulation of hair follicle apoptosis and topobiology during the initiation of follicle cycling.J Invest Dermatol. 1998; 110: 577Google Scholar,Panteleyev et al., 1998dPanteleyev A.A. Paus R. Ahmad W. Sundberg J.P. Christiano A.M. Molecular and functional aspects of the hairless gene in laboratory rodents and humans.Exp Dermatol. 1998; 7: 249-267Crossref PubMed Scopus (118) Google Scholar). These findings suggest that the hairless gene product may play a crucial role in maintaining the balance between cell proliferation, differentiation, and apoptosis in the hair follicle as well as in the interfollicular epidermis. We appreciate the cooperation of the family in this study. This work was supported in part by the National Alopecia Areata Foundation (A.M.C.)