Adams-Oliver syndrome: clinical description of a four-generation family and exclusion of five candidate genes

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.

Dilemmas and challenges in the management of a neonate with Adams-Oliver syndrome with infected giant aplasia cutis lesion and exsanguination: a case-based update

BACKGROUND

Aplasia cutis is a rare developmental anomaly usually involving the calvarium, associated with a variable extent of defective formation of the scalp. Adams-Oliver syndrome is a condition mainly characterized by the congenital absence of skin, known as "aplasia cutis" which is usually limited to the vertex scalp and transverse limb defects.

CASE REPORT

A 17-day-old term female neonate was referred to us with an infected scalp lesion of the vertex. The lesion which is about 10 × 9 cm had signs of infection with necrotic eschar. We started the neonate on systemic parenteral antibiotics with local dressings. On day 3 of conservative management, the neonate had exsanguination due to bleeding from the midline with severe hemodynamic compromise requiring cardiopulmonary resuscitation. After controlling the bleeding with local tamponade and resuscitating the child, she was taken for early surgery. Debridement and bipedicled rotation flap of the scalp to cover the raw area was performed. On day 18, the flap started showing signs of necrosis. The neonate was taken up for debridement, and subsequently, maternal allograft of split-thickness skin was placed as a temporary wound cover. Meanwhile, the wound showed progressive epithelialization. At 1 year, the patient continued to have a non-healing area, which was later successfully covered with a split-thickness skin graft. We plan to revaluate the need for cranioplasty at around 3-4 years of age.

DISCUSSION

We discuss the dilemmas and challenges involved in the successful management of a neonate with Adams-Oliver syndrome with infected aplasia cutis and an episode of life-threatening exsanguination.

CONCLUSION

Aplasia cutis is a rare developmental anomaly usually involving the calvarium, associated with defective formation of the scalp to a varying extent and severity, requiring various timely strategies.

Gain-of-function mutations of ARHGAP31, a Cdc42/Rac1 GTPase regulator, cause syndromic cutis aplasia and limb anomalies

Regulation of cell proliferation and motility is essential for normal development. The Rho family of GTPases plays a critical role in the control of cell polarity and migration by effecting the cytoskeleton, membrane trafficking, and cell adhesion. We investigated a recognized developmental disorder, Adams-Oliver syndrome (AOS), characterized by the combination of aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). Through a genome-wide linkage analysis, we detected a locus for autosomal-dominant ACC-TTLD on 3q generating a maximum LOD score of 4.93 at marker rs1464311. Candidate-gene- and exome-based sequencing led to the identification of independent premature truncating mutations in the terminal exon of the Rho GTPase-activating protein 31 gene, ARHGAP31, which encodes a Cdc42/Rac1 regulatory protein. Mutant transcripts are stable and increase ARHGAP31 activity in vitro through a gain-of-function mechanism. Constitutively active ARHGAP31 mutations result in a loss of available active Cdc42 and consequently disrupt actin cytoskeletal structures. Arhgap31 expression in the mouse is substantially restricted to the terminal limb buds and craniofacial processes during early development; these locations closely mirror the sites of impaired organogenesis that characterize this syndrome. These data identify the requirement for regulated Cdc42 and/or Rac1 signaling processes during early human development.

[Adams-Oliver syndrome: a case with minimal expression]

Adams-Oliver syndrome is a rare congenital anomaly characterized by aplasia cutis congenita (ACC) and variable degrees of terminal transverse limb defects. We report on a neonatal case with the sporadic form of the disease with minimal expression, illustrating the wide spectrum of clinical expression in Adams-Oliver syndrome. We also review the literature and highlight the different pathogenetic hypotheses of this syndrome.

Do children with Adams-Oliver syndrome require endocrine follow-up? New information on the phenotype and management

Adams-Oliver syndrome (AOS) is a rare genetic condition in which the main diagnostic criteria are terminal transverse limb defects and aplasia cutis congenita. Within the spectra of the clinical phenotype of AOS, anthropometric abnormalities have also been reported. We present growth pattern along with hormonal assays in three patients with AOS, one being treated with growth hormone (GH). In Patient 1 (a boy, age 1.9 years), with delayed psychomotor development, epilepsy, deficits of body mass and height, cryptorchidism, low insulin-like growth factor (IGF-1) levels were found and magnetic resonance imaging (MRI) revealed hypoplasia of midline structures of the central nervous system (CNS). In Patient 2 (a girl, age 3.6 years) no significant abnormalities in development, body mass, height or neuroimaging were found. In Patient 3 (a girl, age 8.2 years), with delayed psychomotor development and short stature, low IGF-1 levels and partial GH deficiency were found; MRI revealed small pituitary and polymicrogyria. The girl started GH treatment, improving height velocity and gross coordination. Based on these observations, it seems that intensity of auxologic and hormonal deficits in children with AOS is associated with CNS lesions. Hence, there are indications for neuroimaging and interdisciplinary follow-up of psychomotor development, growth and puberty in this subset of patients with AOS.

A case of adams-oliver syndrome

Adams-Oliver syndrome (AOS) is a congenital condition characterized by aplasia cutis congenita, transverse limb defects, and cutis marmorata telangiectatica. AOS can also be associated with extensive lethal anomalies of internal organs, including the central nervous, cardiopulmonary, gastrourointestinal, and genitourinary systems. Generally, the more severe these interrelated anomalies are, the poorer the prognosis becomes. In the relevant literature on this topic, it is somewhat unclear as to whether the prognosis of AOS without lethal anomalies alters the lifespan. We report a case of AOS with typical skin defects only, and no internal organ anomalies.

The spectra of clinical phenotypes in aplasia cutis congenita and terminal transverse limb defects

The combination of aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD) is often referred to as the eponymous Adams-Oliver syndrome (AOS). The molecular basis of this disorder remains unknown, although the common occurrence of cardiac and vascular anomalies suggests a primary defect of vasculogenesis. Through the description of three previously unreported affected individuals, ascertained through the Adams-Oliver Syndrome European Consortium, we illustrate the phenotypic variability characteristically observed within extended families with AOS. Taken in combination with a detailed review of the available literature, we provide evidence for distinct clinical entities within the ACC/TTLD spectrum, which may reflect genetic heterogeneity within this spectrum of disorders.

Antenatal and postnatal evidence of periventricular leukomalacia as a further indication of vascular disruption in Adams-Oliver syndrome

We describe a new family with Adams-Oliver syndrome (AOS). The propositus is a 14-month-old boy presenting with aplasia cutis congenita, distal limb transverse defects, growth retardation, and a wide atrial septal defect. Central nervous system abnormalities included central hypotonia, and magnetic resonance imaging (MRI) findings consistent with periventricular leukomalacia (PVL). Fetal MRI at 26 weeks' gestation had shown bilateral dilatation of lateral ventricles and periventricular cysts at the site of postnatal lesions. The patient's father and paternal grandfather also had manifestations indicative of AOS. Antenatal and postnatal MRI findings suggest that our patient's PVL represents an unusual congenital feature of AOS, possibly due to vascular disruption and decreased perfusion during critical periods of fetal brain development.