Recurrence of split hand/foot malformation, cleft lip/palate, and severe urogenital abnormalities due to germline mosaicism for TP63 mutation

A newborn with ectrodactyly, tetralogy of Fallot, esophageal atresia, hypospadias and TP63 gene mutation: A new type of EEC Syndrome?

EEC syndrome is an autosomal dominant genetic disease with incomplete penetrance characterized by ectrodactyly, ectodermal dysplasia, and cleft lip/palate; these manifestations can differently occur in the affected subjects and can also be associated with other anomalies, such as in the urogenital tract.We reported the case of a newborn with prenatal diagnosis of EEC type 3 associated with severe cardiac abnormalities (Tetralogy of Fallot), high esophageal atresia with fistula and penoscrotal hypospadias.

Case report: Prenatal diagnosis of Ectrodactyly-Ectodermal dysplasia-Cleft syndrome (EEC) in a fetus with cleft lip and polycystic kidney

Ectrodactyly-ectodermal dysplasia-cleft (EEC) syndrome is an autosomal dominant disorder characterized by ectrodactyly, ectodermal dysplasia, and orofacial clefting. Reduced penetrance is manifested in these core features and additional under-recognized features, especially in prenatal cases. Here, we present a fetus with EEC syndrome at 22 weeks gestation, in which the cleft lip and palate and the right polycystic kidney are shown by prenatal ultrasound. A de novo missense mutation of R304W in the TP63 gene is confirmed by whole-exome sequencing associated with EEC syndrome. We further investigate the reported TP63-related prenatal cases and provide a more complete picture of the prenatal phenotypic spectrum about EEC. It illustrates the potential severity of genitourinary anomalies in TP63-related disorders and highlights the need to counsel for the possibility of EEC syndrome, given the occurrence of genitourinary anomalies with orofacial cleft or limb deformities.

The molecular genetics of human appendicular skeleton

Disorders that result from de-arrangement of growth, development and/or differentiation of the appendages (limbs and digit) are collectively called as inherited abnormalities of human appendicular skeleton. The bones of appendicular skeleton have central role in locomotion and movement. The different types of appendicular skeletal abnormalities are well described in the report of "Nosology and Classification of Genetic skeletal disorders: 2019 Revision". In the current article, we intend to present the embryology, developmental pathways, disorders and the molecular genetics of the appendicular skeletal malformations. We mainly focused on the polydactyly, syndactyly, brachydactyly, split-hand-foot malformation and clubfoot disorders. To our knowledge, only nine genes of polydactyly, five genes of split-hand-foot malformation, nine genes for syndactyly, eight genes for brachydactyly and only single gene for clubfoot have been identified to be involved in disease pathophysiology. The current molecular genetic data will help life sciences researchers working on the rare skeletal disorders. Moreover, the aim of present systematic review is to gather the published knowledge on molecular genetics of appendicular skeleton, which would help in genetic counseling and molecular diagnosis.

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.

Split hand/foot malformation associated with 20p12.1 deletion: A case report

Split hand/foot malformation (SHFM) or ectrodactyly is a rare congenital disorder affecting limb development characterized by clinical and genetic heterogeneity. SHFM is usually inherited as an autosomal dominant trait with incomplete penetrance. Isolated and syndromic forms are described. The extent of associated malformations is highly variable and multiple syndromes with clinical and genetic overlap have been described. We report here a 28 year-old man presenting with SHFM, sparse hair and widespread freckles. Array-CGH identified a 450 kb de novo 20p12.1 microdeletion encompassing three exons (exon 6 to 8) of MACROD2. Although MACROD2 mutations have not been associated with limb malformation until now, it is located next to KIF16B, which is involved in fibroblast growth factor receptor (FGFR) signaling. Additionally, the deletion encompassed a histone modification H3K27ac mark, known as a provider of quantitative readout of promoter and enhancer activity during human limb development. Altogether, these findings suggest that the 20p12.1 CNV is causative of SHFM in the present case through disturbance of regulatory elements functioning.

A novel mutation (c.1010G>T; p.R337L) in TP63 as a cause of split-hand/foot malformation with hypodontia

BACKGROUND

Tumor protein p63 (TP63)-related disorders can be divided into at least six categories, including ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome 3 (EEC syndrome 3), ankyloblepharon-ectodermal defects-cleft lip/palate syndrome (AEC syndrome), acro-dermo-ungual-lacrimal-tooth syndrome (ADULT syndrome), limb-mammary syndrome (LMS), Rapp-Hodgkin syndrome (RHS) and split-hand/foot malformation 4 (SHFM4), and are all a result of heterozygous mutations of TP63. The phenotypes of TP63-related disorders broadly involve ectodermal dysplasias, acromelic malformation and orofacial cleft. SHFM and hypodontia are prominent clinical manifestations of TP63-related disorders.

METHODS

The present study investigated a family with SHFM and hypodontia; determined the sequences of DLX5, WNT8B, WNT10B, BHLHA9, CDH3, DYNC1I1 and FGFR1; and performed single nucleotide polymorphism-array analysis. We detected the mutation by multiple sequence alignments and a bioinformatic prediction.

RESULTS

We identified a novel missense mutation of TP63 (c.1010G>T; R337L) in the family without mutations of DLX5, WNT8B, WNT10B, BHLHA9, CDH3, DYNC1I1, FGFR1 and copy number variants causing SHFM.

CONCLUSIONS

A mutation of TP63 (c.1010G>T; R337L) leads to SHFM with hypodontia. The identification of this mutation expands the spectrum of known TP63 mutations and also may contribute to novel approaches for the genetic diagnosis and counseling of families with TP63-related disorders.