A novel H208D TP63 mutation in a familial case of ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome without clefting

Central nervous system variations and abnormalities in anhidrotic ectodermal dysplasia (AED): neuroimaging findings

BACKGROUND

Anhidrotic ectodermal dysplasia (AED) is a rare, mostly X-linked recessive genodermatosis, characterized by congenital defects of ectodermal derivative structures as the central nervous system (CNS) is primarily ectodermal in origin.

PURPOSE

To evaluate CNS variations and abnormalities in AED.

MATERIAL AND METHODS

A retrospective analysis was made of the neurological and neuroimaging findings of 17 children (12 boys, 5 girls; median age = 8 years; age range = 2-14 years) diagnosed with AED in our pediatric clinics during 2008-2016. The pattern of CNS variation and abnormalities were evaluated by comparing of these findings with an age- and gender-matched healthy control group with no family history.

RESULTS

Of the 17 AED cases identified on the basis of neuroimaging findings, 6 (35.3%) were seen to be normal. Associated CNS variation and abnormalities including cavum septum pellucidum (35.3%), callosal dysgenesis (11.8%), prominent Virchow-Robin spaces (64.7%), cortical sulcal dilation (41.1%), mega cisterna magna (35.3%), focal cortical dysplasia (11.8%), and delayed myelination (58.8%) were observed in 11 (64.7%) children with AED.

CONCLUSION

AED suggests a spectrum of CNS variation and abnormalities, presenting with neurological and neuroimaging findings, demonstrated in the embryonic surface- and neuro-ectoderm derived structures. The results of this study suggest that CNS variation and abnormalities might be associated with AED.

TP63-mutation as a cause of prenatal lethal multicystic dysplastic kidneys

Background

Ectrodactyly‐ectodermal dysplasia‐clefting syndrome 3 (EEC) is one of the six overlapping syndromes caused by mutations in the tumor protein p63 gene (TP63). EEC is suspected when patients have cleft hands or feet, polydactyly, and syndactyly, abnormal development of the ectodermally derived structures, and orofacial clefting. Genitourinary (GU) anomalies have been identified in patients with EEC, yet these are often under‐recognized and under‐reported. The available literature on sonographic prenatal findings is sparse, especially when considering GU anomalies.

Methods

We present the case of a male stillborn fetus, who was found antenatally to have multicystic dysplastic kidneys and anhydramnios. Following the termination of pregnancy, examination and autopsy further revealed unilateral polydactyly and bilateral syndactyly which had not been previously identified on antenatal ultrasound.

Results

Whole‐exome sequencing (WES) revealed a de novo heterozygous pathogenic variant in exon 5 of the TP63 gene: p.His247Arg: c.740A>G (NM_003722.4) which has been reported in the literature. The His247Arg variant has been published as a pathogenic variant in association with EEC, both with and without orofacial clefting.

Conclusion

Our prenatal case expands the phenotypic spectrum of TP63‐related disorders in general. In addition, it adds to the phenotype associated with the His247Arg pathogenic variant responsible for EEC. Further, we highlight the importance of WES as a postnatal tool to help clarify unexpected findings, and as a way to add to the spectrum of existing phenotypes of known single‐gene disorders.

Analysis of large phenotypic variability of EEC and SHFM4 syndromes caused by K193E mutation of the TP63 gene

EEC (ectrodactyly, ectodermal dysplasia, clefting; OMIM 604292) is an autosomal dominant developmental disorder resulting mainly from pathogenic mutations of the DNA-binding domain (DBD) of the TP63 gene. In this study, we showed that K193E mutation in nine affected individuals of a four-generation kindred with a large degree of phenotypic variability causes four different syndromes or TP63-related disorders: EEC, Ectrodactyly-ectodermal dysplasia (EE), isolated ectodermal dysplasia, and isolated Split Hand/Foot Malformation type 4 (SHFM4). Genotype-phenotype and DBD structural modeling analysis showed that the K193-located loop L2-A is associated with R280 through hydrogen bonding interactions, while R280 mutations also often cause large phenotypic variability of EEC and SHFM4. Thus, we speculate that K193 and several other DBD mutation-associated syndromes may share similar pathogenic mechanisms, particularly in the case of the same mutation with different phenotypes. Our study and others also suggest that the phenotypic variability of EEC is attributed, at least partially, to genetic and/or epigenetic modifiers.