University Medical Centre Nijmegen
Professor G.-J. B. van Ommen
Editor-in-Chief of the European Journal of Human Genetics
Leiden University Medical Centre
Department of Human Genetics
Building 2, Zone S-04
P.O. Box 9600
2300 RC Leiden
The Netherlands
Department of Human Genetics
Internal postal code 417
P.O. Box 9101
6500 HB Nijmegen
The Netherlands
Radboud centraal
Geert Grooteplein 10
T +31 24 361 39 46
F +31 24 356 50 26
e.bongers@antrg.umcn.nl
www.umcn.nl
Date
Concerning
February 24th, 2008
Head Prof. dr. H.G. Brunner
Submission of the revised version of the manuscript on entire LMX1B gene deletions in
nail patella syndrome (616-07-EJHG)
Category of manuscript: Short report
Dear Professor van Ommen,
Thank you for the positive response on our manuscript entitled; ‘Identification of entire LMX1B gene
deletions in nail patella syndrome: evidence for haploinsufficiency as the main pathogenic mechanism
underlying dominant inheritance in man’.
Herewith, we send you the revised version of the manuscript.
Please, find enclosed our detailed reaction on the valuable comments of the reviewers.
We hope you will consider the revised version suitable for publication as a ‘Short Report’ in the
European Journal of Human Genetics.
Thank you very much for your attention.
With kindest regards,
Also on behalf of Professor Nine V.A.M. Knoers, MD, PhD,
Yours sincerely,
Ernie M.H.F. Bongers, MD, PhD
Clinical Geneticist
Enclosure:
Overview of the corrections in the present revised version of manuscript 616-07-EJHG
Submission of the revised version of the manuscript on entire LMX1B gene deletions in nail patella syndrome (616-07-EJHG)
Bongers et al., Short report, February 24th 2008
Overview of the corrections in the present revised version of manuscript 616-07-EJHG entitled:
‘Identification of entire LMX1B gene deletions in nail patella syndrome:
evidence for haploinsufficiency as the main pathogenic mechanism underlying dominant inheritance in man’.
Reviewer #1
1) Reviewer #1 questions whether there is enough experimental data available to state that
haploinsufficiency is the main pathogenic mechanism underlying NPS.
In the revised version of this manuscript* we discuss that:
a. Different type of LMX1B mutations result in a similar classic dominant NPS phenotype.
b. Nonsense LMX1B mutations / mutations resulting in premature termination codons (PTCs) are
supposed to cause NPS by degradation of mutant LMX1B transcripts via the nonsensemediated mRNA decay pathway.
c. Previous functional studies support that human missense mutations in the homeodomain of
LMX1B diminish or abolish DNA binding, and ultimately result in decreased transcriptional
activity.
d. Previous mixed transfection studies failed to demonstrate a dominant-negative effect of
missense mutations in LMX1B.
e. Present MLPA analysis revealed entire LMX1B deletions in human NPS.
Ad b. We did not perform experiments to prove that the nonsense/frameshift RNAs of LMX1B are
indeed degraded, but the evidence for the general principality of this pathway is overwhelming.
*Described in the revised version of the manuscript at page 6, paragraph 2, sentence 4 – 9 (Margin #1,1):
‘Comparison of the NPS phenotype … emphasizes that loss-of-function is the predominant mechanism
underlying NPS pathogenesis.’
-
Other points of reviewer #1
2). Additional clinical information/picture etc.
Since this manuscript has been submitted as a short report for the EJHG and is mainly focused on
molecular studies of NPS, we decided not to include a table with clinical findings or photographs
of patients in the manuscript, but to refer to a Supplementary Table for clinical findings in the
revised version instead (Margin #1,2 – page 5). Moreover, the clinical data and photographs of
these patients are similar to those described and presented in our previous article on NPS (Bongers
et al.,2005), to which we refer in the present manuscript. In case that the editor prefers to include
photographs as well, we would be pleased to submit these documents in short time.
3). Remove ‘beyond any doubt’ from the 1st line of discussion (Margin #1, 3).
We removed this from the first line of the discussion in the present revised version.
4). Modification of the title
Since the present MLPA analysis confirms that haploinsufficiency is the predominant mechanism
underlying NPS pathogenesis, we would like to present this conclusion in the title as proposed in
the first version of this manuscript:
‘Identification of entire LMX1B gene deletions in nail patella syndrome: evidence for
haploinsufficiency as the main pathogenic mechanism underlying dominant inheritance in man’.
Reviewer #2
Reviewer #2 suggests to discuss that locus heterogeneity cannot be ruled out in NPS.
Since linkage studies in NPS failed to demonstrate another locus than chromosome 9q34 since
1955, we suppose that locus heterogeneity is highly unlikely.
This subject is discussed in the introduction at page 3 of the revised version: (Margin #2)
‘Linkage studies in NPS families did not reveal evidence for locus heterogeneity thus far.’
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