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Keywords:

  • Nablus mask-like facial syndrome;
  • aCGH;
  • chromosome 8;
  • FAM92A1 gene

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

Microdeletions of 8q21.3–8q22.1 have been identified in all patients with Nablus mask-like facial syndrome (NMLFS). A recent report of a patient without this specific phenotype presented a 1.6 Mb deletion in this region that partially overlapped with previously reported 8q21.3 microdeletions, thus restricting critical region for this syndrome. We report on another case of an 8q21.3 deletion revealed by array comparative genome hybridization (aCGH) in a 4-year-old child with global developmental delay, autism, microcephaly, but without Nablus phenotype. The size of the interstitial deletion was estimated to span 5.2 Mb. By combining the data from previous reports on 8q21.3–8q22.1 deletions and our case, we were able to narrow the critical region of Nablus syndrome to 0.5 Mb. The deleted region includes FAM92A1, which seems to be a potential candidate gene in NMLFS. © 2012 Wiley Periodicals, Inc.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

Nablus mask-like syndrome (NMFLS) is a rare microdeletion syndrome which has been reported in four patients [Shieh et al., 2006]. It is defined by distinctive facial appearance, including blepharophimosis, tight appearing glistening facial skin, a flat and broad nose, distinctive ears, and abnormal hair pattern. Children have happy behavior and moderate developmental delay [Salpietro et al., 2003]. Microdeletions in 8q21.3–8q22.1 regions have been found in all four patients by array comparative genome hybridization (aCGH). The common region in these patients was delineated with proximal deletion breakpoint at 93.56 Mb and distal deletion breakpoint at 96.34 Mb, giving a 2.78 Mb critical region for NMFLS (hg18) [Raas-Rothschild et al., 2009].

A recent report of a patient affected by autism, without NMFLS, presenting an 8q22.1 deletion of 1.6 Mb with breakpoints of 94.8–96.4 Mb permitted to reduce the critical region for NMFLS from position 93.56–94.8 Mb (hg18) [Jain et al., 2010]. We describe here a second case with an 8q21.3–8q22.1 microdeletion from position 89.21–94.3 Mb without NMFLS phenotype, further reducing the NMFLS critical region from 94.3 to 94.8 Mb (hg18).

CLINICAL REPORT

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

The boy was the first child of a healthy nonconsanguineous couple. Pregnancy was unremarkable and he was born at term. Birth weight was 3,550 g, length was 50 cm, and head circumference was 34 cm. He had no feeding difficulties but he presented with sleeping difficulties. At age 8 months, a premature fusion of the anterior fontanel without craniosynostosis was noted. Global developmental delay was established at the age of 21 months with significant speech delay as he was not able to speak at the age of 3 years. He had some autistic traits and stereotypies.

On examination at the age of 3 years, weight was 13.2 kg (+0.5 SD), height 85 cm (−0.5 SD), and head circumference 46 cm (−2.5 SD). He had occipital plagiocephaly, moderate hypertelorism with right epicanthal fold, small bulbous nose with antevertade nostrils, everted lower lip vermilion, and coarse features (Fig. 1). He had two “cafe au lait spots” on the left leg and left ankle, joint laxity of fingers, and bilateral ectopic testes.

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Figure 1. Pictures of our patient. Note occipital plagiocephaly, moderate hypertelorism with right epicanthal fold, small bulbous nose with anteversed nostrils, eversed inferior lip, and heavy traits. [Color figure can be seen in the online version of this article, available at http://wileyonlinelibrary.com/journal/ajmga]

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Ophthamological, audiometric exams, and metabolic explorations were normal. Brain MRI revealed moderate hypomyelinization of the frontal lobes.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

Karyotype

Chromosomal analyses were performed on metaphases obtained from a peripheral blood culture and stained using G- and R-banding techniques according to standard methods.

Array Comparative Genomics Hybridization (aCGH)

Genomic DNA was isolated from blood leucocytes using the NucleoSpin® Blood L extraction kit (Macherey-Nagel, Germany) according to the supplier's protocol.

Microarray-based comparative genomic hybridization (aCGH) was performed using Agilent 105K Whole Human genome Oligo Microarray kit (22 Kb overall median probe spacing (19 Kb in reference sequenced genes)) according to the manufacturer's protocol (Agilent Technologies, Santa Clara, CA).

Genomic copy number aberrations were visualized using the ADM-II algorithm of DNA analytics 4.0.76 (Agilent Technologies).

Fluorescence in Situ Hybridization (FISH)

Fluorescence in situ hybridization (FISH) was performed to confirm the genomic copy number aberration detected by aCGH. Two commercially available probes, RP11-433O22 (BlueFISH, Amplitech®), located at 8q21.3 (89218054–89400934, Genome build 36, hg18) and a chromosome 8p telomeric probe as a control (Vysis®), were used according to the manufacturer's instructions.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

Karyotype was established with a 450 bands resolution and appeared to be normal: 46,XY. aCGH analysis revealed an interstitial deletion of chromosome 8q21.3. The deletion was found to span at least 5.18 Mb in size from chr8: 89114074–94296008 and at most 5.24 Mb in size from chr8: 89067172–94309767 (genome build 36, hg18; Fig. 2A,B). Metaphase FISH analysis showed only one signal of the 8q21.3 probe (RP11-433O22), which confirmed the result of aCGH (Fig. 2C). Since the same FISH analysis performed on his parents did not show any deletion or other rearrangement involving this locus, chromosomal anomaly of the patient was considered to be de novo.

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Figure 2. Results of aCGH for chromosome 8 and FISH analyses of our patient. A: The aberrant area of chromosome 8q21.3 shown in “chromosomal view” is expanded in “gene view” with a weight moving average of 0.2 Mb and threshold of 5.0.Vertical axis indicates gain or loss of genome copy number, and horizontal axis indicates the physical position on chromosome 8. B: Blues rectangles indicate location of the UCSC genes. Red bars indicate the aberrant chromosomal area and the probe position, respectively. Green dots indicate probes, which showed under −0.25 of log2 ratio, and black dots indicate probes, which showed log2 ratio closed to zero (between −0.25 and 0.25). C: Metaphase FISH results obtained with 8q21.3 probe (red) and 8p telomeric probe (green) showing the loss of 8q21.3 probe signal on one of chromosome 8 homologs and thus confirming the presence of a deletion of 8q21.3 region. [Color figure can be seen in the online version of this article, available at http://wileyonlinelibrary.com/journal/ajmga]

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DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

In this study, we report on a de novo 8q21.3–8q22.1 chromosomal deletion of approximately 5.2 Mb in a patient without NMFLS as he lacks the tight appearing glistening facial skin, blepharophimosis, arched sparse eyebrows, and abnormal hair patterning found in the others. By combining the data from all reports on 8q21.3–8q22.1 microdeletions, we were able to reduce the critical region of NMFLS to 0.5 Mb, from position 94.3 to 94.8 Mb and to identify new candidate genes. Several known copy number polymorphisms are included but they do not cover the whole critical region (Database of genomic variants). Five patients in Decipher database are reported with larger deletions of 8q21–q22 region (Patients 253842, 4103, 248172, 2399, and 2514).

Figure 3 illustrates the genes located in the 8q22.1 region, which were proposed to be associated to NMFLS. The first common region, which was delineated from 93.56 to 96.34 Mb in 8q22.1 by Raas-Rothschild et al. [2009] in NFLMS patients included TMEM67 and CCN2, two coding genes, which were thought to be potential candidate genes in this syndrome. However these genes were also deleted in the patient without NMFLS reported by Jain et al. The latter report identified a new restricted critical region of 1.5 Mb (94.8–96.34 Mb). Three new potential candidate genes were discussed: AK128161, a non-coding RNA with unknown function, DKFZp779L1068 and BC089453, two possible coding genes [Jain et al., 2010]. However, these genes were deleted in our patient without NMFLS. A further restriction of the critical region from 94.3 to 94.8 Mb enabled us to propose two new candidate genes: LINC00535 and FAM92A1.

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Figure 3. Comparison of deletion size of the common region described by Raas-Rothschild et al. [2009] (red bars) and Jain et al. [2010] (blue bar) in NMLFS and the deletion in our patient (green bar). White squares represent the overlapped deleted genes. Asterisks represent the genes not deleted in our patient but deleted in the NMLFS patients. Hacked area represents the region not deleted in our patient but deleted in the NMLFS patients. [Color figure can be seen in the online version of this article, available at http://wileyonlinelibrary.com/journal/ajmga]

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LINC00535 (long intergenic non-protein coding RNA 535) is described as a non-coding RNAI of unknown function. According to several genomic databases (GeneCards, Ensembl, UCSC), FAM92A1 (family with sequence similarity 92, member A1, Synonimous symbol FLJ38979) comprises a genomic region of 27.90 kb and encodes a protein of 289 amino acids. Liang et al. [2009] proposed that FAM92A1 could be a new tumor-related gene with an oncogenic potential, which probably plays a role in renal carcinogenesis. This protein may take part in the regulation of cell proliferation and apoptosis [Ruan et al., 2007]. FAM92A1 may interact with APPBP2 (amyloid beat precursor protein binding protein 2) protein that binds microtubules and is functionally associated with beta-amyloid precursor and with CHUK (conserved helix-loop-helix ubiquitous kinase) protein, a multiprotein complex kinase (IKK) (data from I2D database (Interologous Interaction Database)).

CHUK protein plays an essential role in the proliferation and differentiation of skin epidermidis. CHUK mutations are involved in Cocoon syndrome in fetus (OMIM: 613630) [Stevenson et al., 1987]. Cocoon syndrome is a rare recessive autosomic, polymalformative, and lethal syndrome that has been described in only four fetuses with facial malformations, hypoplastic eyeballs, and underdeveloped limbs which are bound to the trunk and encased under the skin. Structure of the skin is abnormal, shiny, tight, thick and adhesive. In 2 fetuses, truncating mutation in the CHUK gene has been identified and resulted in the complete loss of CHUK protein expression [Lahtela et al., 2010]. FAM92A1 deletion could lead either to deregulation of CHUK gene with alteration of CHUK protein expression or alter CHUK protein pathway in epidermidis without loss of CHUK expression. This is compatible with Nablus syndrome as patients have phenotypic traits common with those of fetuses with Cocoon syndrome. Tight glistening skin is reported in both syndromes. In addition, fetuses with Cocoon syndrome have hypoplastic eyeballs, and blepharophimosis is described in NMFLS. It seems that NMFLS may be a limited phenotype of Cocoon syndrome.

In conclusion, the data from the present and previous reports on 8q21.3–8q22.1 deletions enable to narrow the critical region of Nablus syndrome to 0.5 Mb, which points to an interesting candidate gene, FAM92A1 that could deregulate expression or function of CHUK protein in skin. Investigations of CHUK protein expression and function in patients with NMFLS are necessary to determine if this protein is involved in this syndrome.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES

We thank the members of this family for their continuing interest and cooperation. We thank the DGOS (Direction Générale de l'Organisation des Soins) for their support for the development of aCGH platform at Clermont-Ferrand.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORT
  5. MATERIALS AND METHODS
  6. RESULTS
  7. DISCUSSION
  8. INTERNET ADDRESSES
  9. Acknowledgements
  10. REFERENCES
  • Jain S, Yang P, Farrell SA. 2010. A case of 8q22.1 microdeletion without the Nablus mask-like facial syndrome phenotype. Eur J Med Genet 53:108110.
  • Lahtela J, Nousiainen HO, Stefanovic V, Tallila J, Viskari H, Karikoski R, Gentile M, Saloranta C, Varilo T, Salonen R, Kestilä M. 2010. Mutant CHUK and severe fetal encasement malformation. N Engl J Med 363:16311637.
  • Liang S, Gong F, Zhao X, Wang X, Shen G, Xu Y, Yang H, Ruan X, Wei Y. 2009. Prokaryotic expression, purification of a new tumor-relative protein FAM92A1-289 and its characterization in renal cell carcinoma. Cancer Lett 276:8187.
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  • Stevenson R, Saul R, Collins J, Davis W, Lanford C. 1987. Cocoon fetus-fetal encasement secondary to ectodermal dysplasia. Proc Greenwood Genet Center 1015.