Elucidating the genetic architecture of Adams-Oliver syndrome in a large European cohort

Adams–Oliver syndrome (AOS) is a rare developmental disorder, characterized by scalp aplasia cutis congenita (ACC) and transverse terminal limb defects (TTLD). Autosomal dominant forms of AOS are linked to mutations in ARHGAP31, DLL4, NOTCH1 or RBPJ, while DOCK6 and EOGT underlie autosomal recessive inheritance. Data on the frequency and distribution of mutations in large cohorts are currently limited. The purpose of this study was therefore to comprehensively examine the genetic architecture of AOS in an extensive cohort. Molecular diagnostic screening of 194 AOS/ACC/TTLD probands/families was conducted using next‐generation and/or capillary sequencing analyses. In total, we identified 63 (likely) pathogenic mutations, comprising 56 distinct and 22 novel mutations, providing a molecular diagnosis in 30% of patients. Taken together with previous reports, these findings bring the total number of reported disease variants to 63, with a diagnostic yield of 36% in familial cases. NOTCH1 is the major contributor, underlying 10% of AOS/ACC/TTLD cases, with DLL4 (6%), DOCK6 (6%), ARHGAP31 (3%), EOGT (3%), and RBPJ (2%) representing additional causality in this cohort. We confirm the relevance of genetic screening across the AOS/ACC/TTLD spectrum, highlighting preliminary but important genotype–phenotype correlations. This cohort offers potential for further gene identification to address missing heritability.

Expanding the mutational spectrum in Johanson-Blizzard syndrome: identification of whole exon deletions and duplications in the UBR1 gene by multiplex ligation-dependent probe amplification analysis

Background

Johanson‐Blizzard syndrome (JBS, MIM #243800) is a very rare autosomal recessive disorder characterized by exocrine pancreatic insufficiency, nasal wing hypoplasia, hypodontia, and other abnormalities. JBS is caused by mutations of the UBR1 gene (MIM *605981), encoding a ubiquitin ligase of the N‐end rule pathway.

Methods

Molecular findings in a total of 65 unrelated patients with a clinical diagnosis of JBS who were previously screened for UBR1 mutations by Sanger sequencing were reviewed and cases lacking a disease‐causing UBR1 mutation on either one or both alleles were included in this study. In order to discover mutations that are not detectable by Sanger sequencing, we designed a probe set for multiplex ligation‐dependent probe amplification (MLPA) analysis of the UBR1 gene and analyzed the copy number status of all 47 UBR1 exons.

Results

Our previous studies using Sanger sequencing could detect mutations in 93.1% of 130 disease‐associated UBR1 alleles. Six patients with a highly suggestive clinical diagnosis of JBS and unsolved genotype were included in this study. MLPA analysis detected six alleles harboring exon deletions/duplications, thereby raising the mutation detection rate in the entire cohort to 97.7% (127/130 alleles).

Conclusion

We conclude that single or multi‐exon deletions or duplications account for a substantial proportion of JBS‐associated UBR1 mutations.

Oblique facial clefts in Johanson-Blizzard syndrome

Johanson-Blizzard syndrome (JBS) is considered as an infrequent, but clinically easily recognizable autosomal recessive entity by the pathognomonic combination of congenital exocrine pancreatic insufficiency and hypoplastic alae nasi, in addition to other distinctive findings such as scalp defects, hypothyroidism, and rectourogenital malformations. There are few reports of patients with JBS in association with facial clefting, referring all to types 2 to 6 of Tessier's classification that can be characterized properly as oblique facial clefts (OFCs). We describe the clinical aspects in four patients with JBS and extensive OFCs. In all of them, the diagnosis of JBS was confirmed by the demonstration of homozygous or compound-heterozygous mutations in the UBR1 gene. Additionally, we review three previously reported cases of JBS with OFCs. Taking into account a number of approximately 100 individuals affected by JBS that have been published in the literature we estimate that the frequency of OFCs in JBS is between 5% and 10%. This report emphasizes that extensive OFCs may be the severe end of the spectrum of facial malformations occurring in JBS. No obvious genotype phenotype correlation could be identified within this cohort. Thus, UBR1 should be included within the list of contributory genes of OFCs, although the exact mechanism remains unknown. © 2016 Wiley Periodicals, Inc.

DOCK6 Mutations Are Responsible for a Distinct Autosomal-Recessive Variant of Adams-Oliver Syndrome Associated with Brain and Eye Anomalies

The original article to which this Erratum refers was published in Human Mutation 36(6):593–598(DOI:10.1002/humu22795).The authors realized that a co-author, Nuria C. Bramswig, was left off of the title page of this article at the time of submission. This erratum serves to correct this error by including Dr. Bramswig and Dr. Bramswig's institution in the title page information.The authors regret the error.

Two novel UBR1 gene mutations ın a patient with Johanson Blizzard Syndrome: A mild phenotype without mental retardation

Johanson-Blizzard Syndrome (JBS) (MIM #243800) is a rare autosomal recessive genetic disorder characterized by exocrine pancreatic insufficiency, abnormal facial appearance and varying degrees of mental retardation. Mutations in UBR1 gene (MIM *605981) are considered to be responsible for the syndrome. Here, we report a 3 year-old mentally normal JBS girl. The patient presented with exocrine pancreatic insufficiency as well as failure-to-thrive. On dysmorphological examination, she was noted to have an abnormal hair pattern with frontal upsweep and alae nasi hypoplasia. With these findings, JBS diagnosis was established clinically. Molecular analysis of the UBR1 gene revealed two inherited novel mutations; one coming from each parent. These novel mutations were c. 1280T>G and c. 2432+5G>C, and they were found to be disease causing via in-silico analysis. In conclusion, for patients with longstanding exocrine pancreatic insufficiency, it should be considered as being symptomatic of a far broader picture. To omit connection with rare genetic diseases, such as Johanson-Blizzard Syndrome, a detailed dysmorphological examination ought to be performed.

Haploinsufficiency of the NOTCH1 Receptor as a Cause of Adams-Oliver Syndrome With Variable Cardiac Anomalies

BACKGROUND

Adams-Oliver syndrome (AOS) is a rare disorder characterized by congenital limb defects and scalp cutis aplasia. In a proportion of cases, notable cardiac involvement is also apparent. Despite recent advances in the understanding of the genetic basis of AOS, for the majority of affected subjects, the underlying molecular defect remains unresolved. This study aimed to identify novel genetic determinants of AOS.

METHODS AND RESULTS

Whole-exome sequencing was performed for 12 probands, each with a clinical diagnosis of AOS. Analyses led to the identification of novel heterozygous truncating NOTCH1 mutations (c.1649dupA and c.6049_6050delTC) in 2 kindreds in which AOS was segregating as an autosomal dominant trait. Screening a cohort of 52 unrelated AOS subjects, we detected 8 additional unique NOTCH1 mutations, including 3 de novo amino acid substitutions, all within the ligand-binding domain. Congenital heart anomalies were noted in 47% (8/17) of NOTCH1-positive probands and affected family members. In leukocyte-derived RNA from subjects harboring NOTCH1 extracellular domain mutations, we observed significant reduction of NOTCH1 expression, suggesting instability and degradation of mutant mRNA transcripts by the cellular machinery. Transient transfection of mutagenized NOTCH1 missense constructs also revealed significant reduction in gene expression. Mutant NOTCH1 expression was associated with downregulation of the Notch target genes HEY1 and HES1, indicating that NOTCH1-related AOS arises through dysregulation of the Notch signaling pathway.

CONCLUSIONS

These findings highlight a key role for NOTCH1 across a range of developmental anomalies that include cardiac defects and implicate NOTCH1 haploinsufficiency as a likely molecular mechanism for this group of disorders.

DOCK6 mutations are responsible for a distinct autosomal-recessive variant of Adams-Oliver syndrome associated with brain and eye anomalies

Adams-Oliver syndrome (AOS) is characterized by the association of aplasia cutis congenita with terminal transverse limb defects, often accompanied by additional cardiovascular or neurological features. Both autosomal-dominant and autosomal-recessive disease transmission have been observed, with recent gene discoveries indicating extensive genetic heterogeneity. Mutations of the DOCK6 gene were first described in autosomal-recessive cases of AOS and only five DOCK6-related families have been reported to date. Recently, a second type of autosomal-recessive AOS has been attributed to EOGT mutations in three consanguineous families. Here, we describe the identification of 13 DOCK6 mutations, the majority of which are novel, across 10 unrelated individuals from a large cohort comprising 47 sporadic cases and 31 AOS pedigrees suggestive of autosomal-recessive inheritance. DOCK6 mutations were strongly associated with structural brain abnormalities, ocular anomalies, and intellectual disability, thus suggesting that DOCK6-linked disease represents a variant of AOS with a particularly poor prognosis.

Case report. Johanson-Blizzard syndrome: a report of gender-discordant twins with a novel UBR1 mutation

Johanson-Blizzard syndrome (JBS) is a rare autosomal recessive disorder resulting from loss-of-function mutations in the UBR1 gene. JBS can be easily recognized by its unique clinical presentation (including exocrine pancreatic insufficiency, hypoplasia/aplasia of the alae nasi, congenital scalp defects, sensorineural hearing loss, growth retardation, psychomotor retardation, and anal and genitourinary anomalies). The objective of this study is to report on the first familial case of gender-discordant twins presenting JBS and a novel mutation in the UBR1 gene. We also review literature describing molecularly confirmed cases of JBS. The female twin developed refractory severe diarrhea after the second month of life and died at the age of 3 months. The male twin also developed diarrhea and failure to thrive after the 3 month of life but improved when nutrition support and pancreatic enzyme replacement was started, and he has survived into adolescence. Both patients presented typical clinical features of JBS. A homozygous nonsense mutation (c.3682C>T; p.Q1228X) in UBR1 was confirmed. Severe presentation of JBS usually involves deleterious (nonsense, frameshift, or splice-site) mutations in the UBR1 gene that are thought to completely abolish the expression of a functional protein product, as in this familial case; however, milder presentation of JBS has occasionally been observed with missense mutations in at least 1 of the 2 copies of UBR1, in which there may be residual activity of the product of this gene. Early diagnosis and adequate treatment are crucial for a favorable outcome.

Mutations in the human UBR1 gene and the associated phenotypic spectrum

Johanson-Blizzard syndrome (JBS) is a rare, autosomal recessive disorder characterized by exocrine pancreatic insufficiency, typical facial features, dental anomalies, hypothyroidism, sensorineural hearing loss, scalp defects, urogenital and anorectal anomalies, short stature, and cognitive impairment of variable degree. This syndrome is caused by a defect of the E3 ubiquitin ligase UBR1, which is part of the proteolytic N-end rule pathway. Herein, we review previously reported (n = 29) and a total of 31 novel UBR1 mutations in relation to the associated phenotype in patients from 50 unrelated families. Mutation types include nonsense, frameshift, splice site, missense, and small in-frame deletions consistent with the hypothesis that loss of UBR1 protein function is the molecular basis of JBS. There is an association of missense mutations and small in-frame deletions with milder physical abnormalities and a normal intellectual capacity, thus suggesting that at least some of these may represent hypomorphic UBR1 alleles. The review of clinical data of a large number of molecularly confirmed JBS cases allows us to define minimal clinical criteria for the diagnosis of JBS. For all previously reported and novel UBR1 mutations together with their clinical data, a mutation database has been established at LOVD.

Johanson-Blizzard syndrome: hepatic and hematological features with novel genotype

Johanson-Blizzard syndrome (JBS); (OMIM: 243800) presents with features of malabsorption and dysmorphic features with onset of symptoms in infantile age group. The disorder was first described in the year 1971 with report of the first Indian case in 2004. We discuss two rare phenotypes (hepatitis and anemia) in a molecularly confirmed case of JBS.

Johanson-Blizzard syndrome

Johanson-Blizzard syndrome (JBS) is a rare autosomal recessive disease characterized by exocrine pancreatic insufficiency, hypoplastic or aplastic nasal alae, cutis aplasia on the scalp, and other features including developmental delay, failure to thrive, hearing loss, mental retardation, hypothyroidism, dental abnormalities, and anomalies in cardiac and genitourinary systems. More than 60 cases of this syndrome have been reported to date. We describe the case of a male infant with typical symptoms of JBS. In addition, a new clinical feature which has not previously been documented, that is anemia requiring frequent blood transfusions and mild to moderate thrombocytopenia was observed. A molecular study was performed which revealed a novel homozygous UBR1 mutation. Possible explanations for this new association are discussed.

Ubiquitin ligases of the N-end rule pathway: assessment of mutations in UBR1 that cause the Johanson-Blizzard syndrome

BACKGROUND

Johanson-Blizzard syndrome (JBS; OMIM 243800) is an autosomal recessive disorder that includes congenital exocrine pancreatic insufficiency, facial dysmorphism with the characteristic nasal wing hypoplasia, multiple malformations, and frequent mental retardation. Our previous work has shown that JBS is caused by mutations in human UBR1, which encodes one of the E3 ubiquitin ligases of the N-end rule pathway. The N-end rule relates the regulation of the in vivo half-life of a protein to the identity of its N-terminal residue. One class of degradation signals (degrons) recognized by UBR1 are destabilizing N-terminal residues of protein substrates.

METHODOLOGY/PRINCIPAL FINDINGS

Most JBS-causing alterations of UBR1 are nonsense, frameshift or splice-site mutations that abolish UBR1 activity. We report here missense mutations of human UBR1 in patients with milder variants of JBS. These single-residue changes, including a previously reported missense mutation, involve positions in the RING-H2 and UBR domains of UBR1 that are conserved among eukaryotes. Taking advantage of this conservation, we constructed alleles of the yeast Saccharomyces cerevisiae UBR1 that were counterparts of missense JBS-UBR1 alleles. Among these yeast Ubr1 mutants, one of them (H160R) was inactive in yeast-based activity assays, the other one (Q1224E) had a detectable but weak activity, and the third one (V146L) exhibited a decreased but significant activity, in agreement with manifestations of JBS in the corresponding JBS patients.

CONCLUSIONS/SIGNIFICANCE

These results, made possible by modeling defects of a human ubiquitin ligase in its yeast counterpart, verified and confirmed the relevance of specific missense UBR1 alleles to JBS, and suggested that a residual activity of a missense allele is causally associated with milder variants of JBS.

[Cesarean section combined with splenectomy in severely resistant immune thrombocytopenia]

Immune thrombocytopenic purpura (ITP) associated with pregnancy often involves considerable risk both for mother and child, and usually worsens in the third trimester of gestation. Pregnancy and delivery are especially difficult in patients with severe ITP (platelet count below 20 x 10(9)/L), who are resistant to prednisone and high dose intravenous immunoglobulin (IVIgG). In those cases we applied cesarean section (CS), to prevent intracranial haemorrhage due to fetal/neonatal ITP, and splenectomy at the same time as an effective therapeutic strategy for ITP. We present 5 patients (4 with chronic ITP and 1 with ITP associated with HIV infection), aged 21-35 years, with severe ITP (platelet count 2-10 x 109/L), resistant to prednisone (1-2 mg/kg), and 2/3 were resistant to IVIgG (0.4 g/kg x 5 d). Four patients with severe resistant ITP were supported with 1-2 doses of platelets from cell separator before CS and 1-3 dose during splenectomy. One patient increased platelet count to 55 x 109/L after treatment with IVIgG and splenectomy following CS were done without platelet transfusion. Splenectomy was performed immediately after CS in all patients, and two of them were hysterectomised (one with HIV infection). After splenectomy, platelet count was normalised in all patients, and they had no haemorrhage, wound haematoma formation or any adverse events. But ITP relapsed in 2/5 patients after 1-2 months. Two newborns had severe thrombocytopenia, which solved spontaneously after 3 days in one or after treatment with IVIgG in other. We propose that splenectomy following cesarean section should be considered as approach for delivery and treatment option for mothers with severe resistant ITP.

A randomised, multinational study with sequential therapy comparing ciprofloxacin twice daily and ofloxacin once daily

In a multinational, open, randomised, controlled clinical study, 474 hospitalised patients with moderate or severe infections were treated with sequential regimens of ofloxacin or ciprofloxacin. Ofloxacin 400 mg once daily or ciprofloxacin 200 mg twice daily were given intravenously for at least 3 days followed by oral treatment with ofloxacin 400 mg once daily or ciprofloxacin 500 mg twice daily. Overall cure rates of 86.8% (85.7%) in the ofloxacin group and 89.6 (89.5%) in the ciprofloxacin group were achieved in the intention-to-treat analysis (per protocol analysis). The overall bacteriological response rate (ofloxacin 89.5%, ciprofloxacin 89.0%) was comparable to the clinical cure rate. Both drugs were well tolerated and adverse events were rarely observed. It is concluded that ofloxacin and ciprofloxacin can be used successfully in the treatment of hospitalised patients with aerobic gram-positive and gram-negative infections. Ofloxacin has the advantage of a once-daily regimen, compared to the twice-daily regimen with ciprofloxacin.