Mutations in CHD7, encoding a chromatin-remodeling protein, cause idiopathic hypogonadotropic hypogonadism and Kallmann syndrome.
CHARGE syndrome and Kallmann syndrome (KS) are two distinct developmental disorders sharing overlapping features of impaired olfaction and hypogonadism. KS is a genetically heterogeneous disorder consisting of idiopathic hypogonadotropic hypogonadism (IHH) and anosmia, and is most commonly due to KAL1 or FGFR1 mutations. CHARGE syndrome, a multisystem autosomal-dominant disorder, is caused by CHD7 mutations. We hypothesized that CHD7 would be involved in the pathogenesis of IHH and KS (IHH/KS) without the CHARGE phenotype and that IHH/KS represents a milder allelic variant of CHARGE syndrome. Mutation screening of the 37 protein-coding exons of CHD7 was performed in 101 IHH/KS patients without a CHARGE phenotype. In an additional 96 IHH/KS patients, exons 6-10, encoding the conserved chromodomains, were sequenced. RT-PCR, SIFT, protein-structure analysis, and in situ hybridization were performed for additional supportive evidence. Seven heterozygous mutations, two splice and five missense, which were absent in > or = 180 controls, were identified in three sporadic KS and four sporadic normosmic IHH patients. Three mutations affect chromodomains critical for proper CHD7 function in chromatin remodeling and transcriptional regulation, whereas the other four affect conserved residues, suggesting that they are deleterious. CHD7's role is further corroborated by specific expression in IHH/KS-relevant tissues and appropriate developmental expression. Sporadic CHD7 mutations occur in 6% of IHH/KS patients. CHD7 represents the first identified chromatin-remodeling protein with a role in human puberty and the second gene to cause both normosmic IHH and KS in humans. Our findings indicate that both normosmic IHH and KS are mild allelic variants of CHARGE syndrome and are caused by CHD7 mutations.
Kim
Hyung-Goo
HG
Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA.
Kurth
Ingo
I
Lan
Fei
F
Meliciani
Irene
I
Wenzel
Wolfgang
W
Eom
Soo Hyun
SH
Kang
Gil Bu
GB
Rosenberger
Georg
G
Tekin
Mustafa
M
Ozata
Metin
M
Bick
David P
DP
Sherins
Richard J
RJ
Walker
Steven L
SL
Shi
Yang
Y
Gusella
James F
JF
Layman
Lawrence C
LC
D000595:Amino Acid Sequence; D001483:Base Sequence; D002843:Chromatin / Q000737:chemistry; D004265:DNA Helicases / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons; D005260:Female; D006801:Humans; D007006:Hypogonadism / Q000235:genetics*; D017436:Kallmann Syndrome / Q000235:genetics*; D008297:Male; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D002843:Chromatin; D004268:DNA-Binding Proteins; D004265:DNA Helicases; C491434:CHD7 protein, human