Sensenbrenner syndrome: a further challenge in evaluating sagittal synostosis and a need for a multidisciplinary approach

Technical evolution of pediatric neurosurgery: craniosynostosis from 1972 to 2023 and beyond

Very few clinical entities have undergone so many different treatment approaches over such a short period of time as craniosynostosis. Surgical treatments for this condition have ranged from simple linear craniectomies, accounting for the specific role of cranial sutures in assuring the normal growth of the skull, to more complex cranial vault reconstructions, based on the perceived role of the skull base in affecting the growth of the skull. While a great deal of evolution has occurred, there remains controversy regarding the ideal treatment including the best surgical technique, the optimal age for surgery, and the long-term morphological and neurodevelopmental outcomes. The evolution of the surgical management of craniosynostosis in the last 50 years has been affected by several factors. This includes the awareness of needing to operate on affected children during infancy to achieve the best results, the use of multistage operations, the availability of more sophisticated surgical tools, and improved perioperative care. In some forms of craniosynostosis, the operations can be carried out at a very young age with low morbidity, and with the postoperative use of a molding helmet, springs, or distractors, these operations prove to be as effective as traditional larger cranial reconstructions performed in older children. As a consequence, complex surgical operations have become progressively less utilized. A second relevant advance was the more recent advent of a molecular diagnosis, which allowed us to understand the pathogenesis of some associated malformations and neurodevelopmental issues that were observed in some children despite appropriate surgical treatment. Future research should focus on improving the analysis of longer-term outcomes and understanding the natural history of craniofacial conditions, including what issues persist despite optimal surgical correction. Progress in molecular investigations concerning the normal and pathological development of cranial sutures could be a further significant step in the management of craniosynostosis, possibly favoring a "medical" treatment in the near future. Artificial intelligence will likely have a role in establishing the diagnosis with less reliance on radiographic studies and in assisting with surgical planning. Overall, much progress has been made, but there remains much to do.

Novel compound heterozygous WDR35 variants in a Chinese patient associated with cranioectodermal dysplasia and ectopic testis: a case report and review of the literature

BACKGROUND

WDR35 variants are known to cause a rare autosomal recessive disorder-Cranioectodermal dysplasia (CED). The CED patients are commonly present with facial dysmorphisms (frontal bossing and low-set ears), sagittal craniosynostosis, growth retardation, dolichocephaly, skeletal deformities (brachydactyly, terminal hypoplasia of the fingers and narrow thorax), ectodermal abnormalities (sparse hair, and finger/toe nail dysplasia), nephronophthisis, retinal dystrophy and hepatic fibrosis. Diagnosis of CED can be difficult because it presents with high genetic heterogeneity. However, our understanding of the phenotype of CED caused by WDR35 variants could be more explicit, and the correlation between genotype and phenotype needs further improvement.

CASE PRESENTATION

We report a case of the first Chinses patient of CED caused by WDR35 variants, a 3-year-and-3-month-old patient, who was admitted to our hospital with frontal bossing, growth retardation, low set ears, dolichocephaly, sparse hair, and small limbs, abnormal renal function, and moderate anemia. The child showed a novel phenotype of the ectopic testis except for presenting typical CED characteristics, and he was identified with novel compound heterozygous WDR35 variants (c.2590 C > T, p.Gln864* and c.2408_2416del, p.Asn803_Ala805del; NM_001006657). He was given iron succinate and erythropoietin to improve anemia and to inhibit repeated metabolic acidosis and hyperkalemia through acid correction, diuretic, and potassium-lowering treatments. The parents refused to accept renal replacement therapy for their child and were discharged voluntarily.

CONCLUSIONS

This is the first reported case of the WDR35 variants that can lead to CED and ectopic testis, which is also the first Chinese patient associated with WDR35 variants. This study expands our understanding of genotype-phenotype association in patients with WDR35 variants and provides genetic counseling for prevention and intervention in this genetic disorder. Neonatal carriers should be followed up for kidney and CED-related diseases to detect warning signs.

WDR35 variants in a cranioectodermal dysplasia patient with early onset end-stage renal disease and retinal dystrophy

Cranioectodermal dysplasia (CED) is rare heterogeneous condition. It belongs to a group of disorders defined as ciliopathies and is associated with defective cilia function and structure. To date six genes have been associated with CED. Here we describe a 4-year-old male CED patient whose features include dolichocephaly, multi-suture craniosynostosis, epicanthus, frontal bossing, narrow thorax, limb shortening, and brachydactyly. The patient presented early-onset chronic kidney disease and was transplanted at the age of 2 years and 5 months. At the age of 3.5 years a retinal degeneration was diagnosed. Targeted sequencing by NGS revealed the presence of compound heterozygous variants in the WDR35 gene. The variants are a novel missense change in exon 9 p.(Gly303Arg) and a previously described nonsense variant in exon 18 p.(Leu641*). Our findings suggest that patients with WDR35 defects may be at risk to develop early-onset retinal degeneration. Therefore, CED patients with pathogenic variation in this gene should be assessed at least once by the ophthalmologist before the age of 4 years to detect early signs of retinal degeneration.

Case Report: Sequential Liver After Kidney Transplantation in a Patient With Sensenbrenner Syndrome (Cranioectodermal Dysplasia)

Sensenbrenner syndrome, also known as cranioectodermal dysplasia (CED), is a rare ciliopathy clinically characterized by congenital craniofacial, skeletal, and ectodermal defects. Chronic kidney and liver insufficiency are also present in this disorder. Cranioectodermal dysplasia is an autosomal recessive and heterogeneous genetic disease. Six genes (IFT122, WDR35, IFT140, IFT43, IFT52, and WDR19) are known to be associated with this syndrome. Until 2021 more than 70 patients have been reported with CED, however, an orthotopic liver transplantation has been reported only in one case. Here, we present a case report of sequential liver-after-kidney transplantation in a male patient affected by CED. The kidney and liver transplantation was performed at the age of 7 and 12 years, respectively. Patients with Sensenbrenner syndrome require a multidisciplinary medical management and should regularly be followed-up by hepatologists and nephrologists, as the liver and kidney diseases are the major cause of morbidity and mortality.