Missense variant in UBA2 associated with aplasia cutis congenita, duane anomaly, hip dysplasia and other anomalies: A possible new disorder involving the SUMOylation pathway

A somatic UBA2 variant preceded ETV6-RUNX1 in the concordant BCP-ALL of monozygotic twins

Genetic analysis of leukemic clones in monozygotic twins with concordant acute lymphoblastic leukemia (ALL) has proved a unique opportunity to gain insight into the molecular phylogenetics of leukemogenesis. Using whole-genome sequencing, we characterized constitutional and somatic single nucleotide variants/insertion-deletions (indels) and structural variants in a monozygotic twin pair with concordant ETV6-RUNX1+ B-cell precursor ALL (BCP-ALL). In addition, digital PCR (dPCR) was applied to evaluate the presence of and quantify selected somatic variants at birth, diagnosis, and remission. A shared somatic complex rearrangement involving chromosomes 11, 12, and 21 with identical fusion sequences in leukemias of both twins offered direct proof of a common clonal origin. The ETV6-RUNX1 fusion detected at diagnosis was found to originate from this complex rearrangement. A shared somatic frameshift deletion in UBA2 was also identified in diagnostic samples. In addition, each leukemia independently acquired analogous deletions of 3 genes recurrently targeted in BCP-ALLs (ETV6, ATF7IP, and RAG1/RAG2), providing evidence of a convergent clonal evolution only explained by a strong concurrent selective pressure. Quantification of the UBA2 deletion by dPCR surprisingly indicated it persisted in remission. This, for the first time to our knowledge, provided evidence of a UBA2 variant preceding the well-established initiating event ETV6-RUNX1. Further, we suggest the UBA2 deletion exerted a leukemia predisposing effect and that its essential role in Small Ubiquitin-like Modifier (SUMO) attachment (SUMOylation), regulating nearly all physiological and pathological cellular processes such as DNA-repair by nonhomologous end joining, may hold a mechanistic explanation for the predisposition.

A successful case of preimplantation genetic testing for monogenic disorder for aplasia cutis congenita

BACKGROUND

Aplasia cutis congenita (ACC), also called congenital cutaneous hypoplasia, is a serious disease in newborns. Children with ACC often die due to wound infections and bleeding. How the incidence of ACC can be reduced is a question that needs to be solved urgently.

CASE REPORT

We reported a mother who had delivered two children with ACC, both of whom were diagnosed with ACC type VI, skin defects, limb deformities, and congenital heart malformations. One infant died a few days after birth, and another died in utero in the second trimester. Genetic testing in both children showed a heterozygous mutation in the ITGB4 gene [17q25 exon 8, c. 794 dupC, (p. Ala266fs) and exon 15, c. 1860G > A]. The mother later successfully gave birth to a healthy baby using Preimplantation Genetic Testing for Monogenic disorders(PGD-M).

CONCLUSION

The PGD-M technique is highly valuable in reducing the incidence of ACC and improving the prognoses of newborns.

WTIP upregulates FOXO3a and induces apoptosis through PUMA in acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive and heterogeneous clonal hematologic malignancy for which novel therapeutic targets and strategies are required. Emerging evidence suggests that WTIP is a candidate tumor suppressor. However, the molecular mechanisms of WTIP in leukemogenesis have not been explored. Here, we report that WTIP expression is significantly reduced both in AML cell lines and clinical specimens compared with normal controls, and low levels of WTIP correlate with decreased overall survival in AML patients. Overexpression of WTIP inhibits cell proliferation and induces apoptosis both in vitro and in vivo. Mechanistic studies reveal that the apoptotic function of WTIP is mediated by upregulation and nuclear translocation of FOXO3a, a member of Forkhead box O (FOXO) transcription factors involved in tumor suppression. We further demonstrate that WTIP interacts with FOXO3a and transcriptionally activates FOXO3a. Upon transcriptional activation of FOXO3a, its downstream target PUMA is increased, leading to activation of the intrinsic apoptotic pathway. Collectively, our results suggest that WTIP is a tumor suppressor and a potential target for therapeutic intervention in AML.

Deciphering the mutational signature of congenital limb malformations

Congenital limb malformations (CLMs) affect 1 in 500 live births. However, the value of exome sequencing (ES) for CLM is lacking. The purpose of this study was to decipher the mutational signature of CLM on an exome level. We enrolled a cohort of 66 unrelated probands (including 47 families) with CLM requiring surgical correction. ES was performed for all patients and available parental samples. A definite molecular diagnosis was achieved in 21 out of 66 (32%) patients. We identified 19 pathogenic or likely pathogenic single-nucleotide variants and three copy number variants, of which 11 variants were novel. We identified four variants of uncertain significance. Additionally, we identified RPL9 and UBA2 as novel candidate genes for CLM. By comparing the detailed phenotypic features, we expand the phenotypic spectrum of diastrophic dysplasia and chromosome 6q terminal deletion syndrome. We also found that the diagnostic rate was significantly higher in patients with a family history of CLM (p = 0.012) or more than one limb affected (p = 0.034). Our study expands our understanding of the mutational and phenotypic spectrum of CLM and provides novel insights into the genetic basis of these syndromes.

Genotype-phenotype correlations of UBA2 mutations in patients with ectrodactyly

Interstitial 19q13.11 deletions are associated with ectrodactyly, which has recently been linked to loss-of-function of the UBA2 gene. We report a boy with a de novo frameshift mutation in UBA2 (c.612delA (p.(Glu205Lysfs*63)), presenting with ectrodactyly of the feet associated with learning difficulties and minor physical anomalies. We review genotype-phenotype correlations in patients with chromosomal 19q13.11 microdeletions compared to those with intragenic UBA2 mutations.

Treating aplasia cutis congenita in a newborn with the combination of ionic silver dressing and moist exposed burn ointment: A case report

BACKGROUND

Aplasia cutis congenita (ACC) in newborns is a condition in which congenital defects or hypoplasia is present in part of the epidermis, dermis and even subcutaneous tissue (including muscle and bones). First reported by Cordon in 1767, ACC is a rare disease with a low incidence of 1/100000 to 3/10000. Currently, there are 500 cases reported worldwide. ACC can be accompanied by other malformations. The onset mechanism of the disease remains unknown but is thought to be correlated to factors such as genetics, narrow uterus, foetal skin and amniotic membrane adhesion, use of teratogenic drugs in early pregnancy and viral infection.

CASE SUMMARY

In August 2018, we treated a newborn with ACC on the left lower limbs using a combination of ionic silver dressing and moist exposed burn ointment (MEBO) and achieved a satisfactory treatment outcome. The skin defects were observed on the external genitals and on areas from the left foot to 3/4 of the upper left side. Subcutaneous tissue and blood vessels were observed in the regions with skin defects. The following treatments were provided. First, the wound was rinsed with 0.9% sodium chloride solution followed by disinfection with povidone-iodine twice. And then MEBO was applied to the wound at a thickness of approximately 1 mm. After applying ionic silver dressing, the wound was covered with sterile gauze. The wound dressing was replaced every 2-3 d. At the 4-mo follow-up, the treatment outcome was satisfactory. There was minimal scar tissue formation, and limb function was not impaired.

CONCLUSION

The combination of ionic silver dressing and MEBO to ACC is helpful.

Comprehensive clinical and molecular studies in split-hand/foot malformation: identification of two plausible candidate genes (LRP6 and UBA2)

Split-hand/foot malformation (SHFM) is a clinically and genetically heterogeneous condition. We sequentially performed screening of the previously identified Japanese founder 17p13.3 duplication/triplication involving BHLHA9, array comparative genomic hybridization, and whole exome sequencing (WES) in newly recruited 41 Japanese families with non-syndromic and syndromic SHFM. We also carried out WES in seven families with nonsyndromic and syndromic SHFM in which underlying genetic causes including pathogenic copy-number variants (CNVs) remained undetected in our previous studies of 56 families. Consequently, we identified not only known pathogenic CNVs (17p13.3 duplications/triplications [n = 21], 2q31 deletion [n = 1], and 10q24 duplications [n = 3]) and rare variants in known causative genes (TP63 [n = 3], DLX5 [n = 1], IGF2 [n = 1], WNT10B [n = 3], WNT10B/PORCN [n = 1], and PORCN [n = 1]), but also a de novo 19q13.11 deletion disrupting UBA2 (n = 1) and variants that probably affect function in LRP6 (n = 1) and UBA2 (n = 1). Thus, together with our previous data based on testing of 56 families, molecular studies for a total of 97 families with SHFM revealed underlying genetic causes in 75 families, and clinical studies for the 75 families indicated a certain degree of correlation between genetic causes and phenotypes. The results imply that SHFM primarily occurs as a genetic disorder with genotype-phenotype correlations. Furthermore, the results together with previous data such as the development of SHFM in Lrp6 knockout mice, the presence of SHFM in two subjects with 19q13 deletions involving UBA2, and strong mouse Uba2 expression in the developing limb buds, imply that LRP6 and UBA2 represent plausible candidate genes for SHFM.

Autopsy findings of ectodermal dysplasia and sex development disorder in a fetus with 19q12q13 microdeletion

A 5,6 Mb de novo 19q12-q13.12 interstitial deletion was diagnosed prenatally by array-comparative genomic hybridization in a 26 weeks male fetus presenting with intra-uterine growth retardation, left clubfoot, atypical genitalia and dysmorphic features. Autopsic examination following termination of pregnancy identified a severe disorder of sex development (DSD) including hypospadias, micropenis, bifid scrotum and right cryptorchidism associated with signs of ectodermal dysplasia: scalp hypopigmentation, thick and frizzy hair, absence of eyelashes, poorly developed nails and a thin skin with prominent superficial veins. Other findings were abnormal lung lobation and facial dysmorphism. This new case of DSD with a 19q12q13 deletion expands the phenotypic spectrum associated with this chromosomal rearrangment and suggests that WTIP is a strong candidate gene involved in male sex differentiation.

19q13.11 microdeletion: Clinical features overlapping ectrodactyly ectodermal dysplasia-clefting syndrome phenotype

We report a patient who was followed for a long time under an ectrodactyly ectodermal dysplasia-clefting (EEC) syndrome and was subsequently diagnosed with a 19q13.11 microdeletion. After a review of the related literature, we suggest testing patients with EEC for 19q13.11 microdeletion and include WTIP and UBA2 to a minimal overlapping region.

Aplasia cutis congenita: Two case reports and discussion of the literature

Background:

Aplasia cutis congenita (ACC) is a part of a heterogeneous group of conditions characterized by the congenital absence of epidermis, dermis, and in some cases, subcutaneous tissues or bone usually involving the scalp vertex. There is an estimated incidence of 3 in 10,000 births resulting in a total number of 500 reported cases to date. The lesions may occur on every body surface although localized scalp lesions form the most frequent pattern (70%). Complete aplasia involving bone defects occurs in approximately 20% of cases. ACC can occur as an isolated defect or can be associated with a number of other congenital anomalies such as limb anomalies or embryologic malformations. In patients with large scalp and skull defects, there is increased risk of infection and bleeding along with increased mortality and therefore prompt and effective management is advised.

Case Description:

We describe two cases of ACC, involving a 4 × 3 cm defect managed conservatively and a larger 10 × 5 cm defect managed surgically with the use of a temporo-occipital scalp flap. Both cases had an excellent outcome.

Conclusions:

Multiple treatment regimens exist for ACC, but there is no consensus on treatment strategies. Conservative treatment has been described and advocated, but many authors have emphasized the disadvantages of this treatment modality. Decision between conservative and surgical management must be individualized according to lesion size and location.