Three novel missense mutations within the LHX4 gene are associated with variable pituitary hormone deficiencies.
BACKGROUND
The LHX4 LIM-homeodomain transcription factor has essential roles in pituitary gland and nervous system development. Heterozygous mutations in LHX4 are associated with combined pituitary hormone deficiency.


OBJECTIVE
Our objectives were to determine the nature and frequency of LHX4 mutations in patients with pituitary hormone deficiency and to examine the functional outcomes of observed mutations.


METHODS
The LHX4 gene sequence was determined from patient DNA. The biochemical and gene regulatory properties of aberrant LHX4 proteins were characterized using structural predictions, pituitary gene transcription assays, and DNA binding experiments.


METHODS
A total of 253 patients from 245 pedigrees with GH deficiency and deficiency of at least one additional pituitary hormone was included in the study.


RESULTS
In five patients, three types of heterozygous missense mutations in LHX4 that result in substitution of conserved amino acids were identified. One substitution is between the LIM domains (R84C); the others are in the homeodomain (L190R; A210P). The patients have GH deficiency; some also display reductions in TSH, LH, FSH, or ACTH, and aberrant pituitary morphology. Structural models predict that the aberrant L190R and A210P LHX4 proteins would have impaired DNA binding and gene activation properties. Consistent with these models, EMSAs and transfection experiments using pituitary gene promoters demonstrate that whereas the R84C form has reduced activity, the L190R and A210P proteins are inactive.


CONCLUSIONS
LHX4 mutations are a relatively rare cause of combined pituitary hormone deficiency. This report extends the range of phenotypes associated with LHX4 gene mutations and describes three novel exonic mutations in the gene.
Pfaeffle
Roland W
RW
University Children's Hospital, Leipzig, Germany.
Hunter
Chad S
CS
Savage
Jesse J
JJ
Duran-Prado
Mario
M
Mullen
Rachel D
RD
Neeb
Zachary P
ZP
Eiholzer
Urs
U
Hesse
Volker
V
Haddad
Nadine G
NG
Stobbe
Heike M
HM
Blum
Werner F
WF
Weigel
Johannes F W
JF
Rhodes
Simon J
SJ
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000378:metabolism; D005260:Female; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D007223:Infant; D060850:LIM-Homeodomain Proteins; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010907:Pituitary Hormones / Q000172:deficiency*; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D018398:Homeodomain Proteins; C486362:LHX4 protein, human; D060850:LIM-Homeodomain Proteins; D010907:Pituitary Hormones; D014157:Transcription Factors; D004247:DNA