Oral Manifestations of Wolf-Hirschhorn Syndrome: Genotype-Phenotype Correlation Analysis

Detection of 4p16.3 deletion and 11p15.5p15.4 gain in a boy by comparative genomic hybridization array: A case report

BACKGROUND

Nonallelic homologous recombination (NAHR) of segmental duplications or low copy repeats (LCRs) result in DNA gain/loss and play an important role in the origin of genomic disorders.

CASE SUMMARY

A 3-year- old boy was referred for genetic analysis. Comparative genomic hybridization array analysis revealed a loss of 3776 kb in the 4p16.3 chromosomal region and a gain of 3201 kb in the 11p15.5p15.4 chromosomal region.

CONCLUSION

Genomic imbalances caused by NAHR in LCRs result in deletion and duplication syndromes.

Wolf-Hirschhorn syndrome candidate 1 (Whsc1) methyltransferase signals via a Pitx2-miR-23/24 axis to effect tooth development

Wolf-Hirschhorn syndrome (WHS) is a developmental disorder attributed to a partial deletion on the short arm of chromosome 4. WHS patients suffer from oral manifestations including cleft lip and palate, hypodontia, and taurodontism. WHS candidate 1 (WHSC1) gene is a H3K36-specific methyltransferase that is deleted in every reported case of WHS. Mutation in this gene also results in tooth anomalies in patients. However, the correlation between genetic abnormalities and the tooth anomalies has remained controversial. In our study, we aimed to clarify the role of WHSC1 in tooth development. We profiled the Whsc1 expression pattern during mouse incisor and molar development by immunofluorescence staining and found Whsc1 expression is reduced as tooth development proceeds. Using real-time quantitative reverse transcription PCR, Western blot, chromatin immunoprecipitation, and luciferase assays, we determined that Whsc1 and Pitx2, the initial transcription factor involved in tooth development, positively and reciprocally regulate each other through their gene promoters. miRNAs are known to regulate gene expression posttranscriptionally during development. We previously reported miR-23a/b and miR-24-1/2 were highly expressed in the mature tooth germ. Interestingly, we demonstrate here that these two miRs directly target Whsc1 and repress its expression. Additionally, this miR cluster is also negatively regulated by Pitx2. We show the expression of these two miRs and Whsc1 are inversely correlated during mouse mandibular development. Taken together, our results provide new insights into the potential role of Whsc1 in regulating tooth development and a possible molecular mechanism underlying the dental defects in WHS.

Features of the Wolf-Hirschhorn Syndrome (WHS) from Infant to Young Teenager

Wolf-Hirschhorn syndrome is a rare condition caused by terminal deletions, of variable size, in the short arm of chromosome 4. The syndrome displays the combination of typical morphological facial variations, intellectual disability, language delay, and various malformations. This report describes the clinical aspect and developmental evolution of a male patient with Wolf-Hirschhorn syndrome, from infancy to adolescence. The patient was first examined and diagnosed at 11 months, with follow-up at the ages of 4 and 16.

"A practical approach to dental care for patients with Wolf-Hirschhorn syndrome"

Wolf-Hirschhorn syndrome is a polymalformative chromosomal disorder caused by a deletion in the distal region of the short arm of chromosome 4. The disease is considered rare (1/50,000 births) and predominantly affects females (2:1). In addition to the characteristic facial phenotype ("Greek warrior helmet"), its clinical manifestations include epilepsy, developmental and psychomotor delay, intellectual disability, cardiac and respiratory complications, and eating problems. The most prevalent oral manifestations are hypodontia, delayed tooth eruption, morphological dental abnormalities, dental malocclusions, cleft lip/palate and ogival palate. Based on our clinical experience, Wolf-Hirschhorn syndrome does not represent an absolute contraindication for any type of dental procedure. The feasibility of dental treatment will depend mainly on the degree of epilepsy control and on the level of collaboration, this latter conditioned by the severity of the intellectual disability and communication difficulties.

Wolf-Hirschhorn Syndrome: Clinical and Genetic Study of 7 New Cases, and Mini Review

Wolf–Hirschhorn syndrome (WHS), a rare disorder determined by distal 4p deletion, is characterized by a pre and postnatal growth retardation, hypotonia, intellectual disability, epilepsy, craniofacial dysmorphism, and congenital fusion anomalies. The clinical aspects are dependent on the deletion’ size. Our aim was to identify rare specific characteristics in a cohort of seven cases with 4p deletion and to assess the utility of Multiplex ligation-dependent probe amplification (MLPA) (cheap and sensitive test)—combined kits—as a diagnostic test and selection tool for cases that require other investigations (chromosomal microarray analysis—CMA, karyotype). For all cases we conducted a clinical examination with the main features identified: facial dysmorphism, intellectual disability, postnatal development delay, cardiac defects and hypotonia. In some cases, we observed seizures, structural brain abnormalities, immunodeficiencies, and renal anomalies. Prenatal growth retardation was detected in a relatively small number of cases, but postnatal growth failure was a constant feature. In all cases, the clinical diagnosis was confirmed by genetic analyses: karyotype and/or MLPA. In conclusion, renal and brain defects, as well as immunodeficiency are rare manifestations and should be looked for. Although CMA is the standard test, in our experience, MLPA is also a reliable screening method as the identified cases were either confirmed by MLPA or selected for further investigations.