Wide Fontanels, Delayed Speech Development and Hoarse Voice as Useful Signs in the Diagnosis of KBG Syndrome: A Clinical Description of 23 Cases with Pathogenic Variants Involving the ANKRD11 Gene or Submicroscopic Chromosomal Rearrangements of 16q24.3.

KBG syndrome is a neurodevelopmental autosomal dominant disorder characterized by short stature, macrodontia, developmental delay, behavioral problems, speech delay and delayed closing of fontanels. Most patients with KBG syndrome are found to have a mutation in the ANKRD11 gene or a chromosomal rearrangement involving this gene. We hereby present clinical evaluations of 23 patients aged 4 months to 26 years manifesting clinical features of KBG syndrome. Mutation analysis in the patients was performed using panel or exome sequencing and array CGH. Besides possessing dysmorphic features typical of the KBG syndrome, nearly all patients had psychomotor hyperactivity (86%), 81% had delayed speech, 61% had poor weight gain, 56% had delayed closure of fontanel and 56% had a hoarse voice. Macrodontia and a height range of -1 SDs to -2 SDs were noted in about half of the patients; only two patients presented with short stature below -3 SDs. The fact that wide, delayed closing fontanels were observed in more than half of our patients with KBG syndrome confirms the role of the ANKRD11 gene in skull formation and suture fusion. This clinical feature could be key to the diagnosis of KBG syndrome, especially in young children. Hoarse voice is a previously undescribed phenotype of KBG syndrome and could further reinforce clinical diagnosis.

Variants of ATP1A3 in residue 756 cause a separate phenotype of relapsing encephalopathy with cerebellar ataxia (RECA)-Report of two cases and literature review.

BACKGROUND: Variants in ATP1A3 cause well-known phenotypes-alternating hemiplegia of childhood (AHC), rapid-onset dystonia-parkinsonism (RDP), cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss (CAPOS), and severe early infantile epileptic encephalopathy. Recently, there has been growing evidence for genotype-phenotype correlations in the ATP1A3 variants, and a separate phenotype associated with variants in residue 756-two acronyms are proposed for the moment-FIPWE (fever-induced paroxysmal weakness and encephalopathy) and RECA (relapsing encephalopathy with cerebellar ataxia). MATERIALS AND METHODS: Herein, we are describing two new pediatric cases with a p.Arg756His change in the ATP1A3 gene. Both patients have had more than one episode of a neurological decompensation triggered by fever with severe hypotonia and followed by ataxia. Thirty-three cases from literature were analyzed to define and strengthen the genotype-phenotype correlation of variants located in residue 756 (p.Arg756His, p.Arg756Cys, p.Arg756Leu). CONCLUSIONS: Patients with a ATP1A3 variant in residue 756 are characterized by recurrent paroxysmal episodes of neurological decompensations triggered by fever, with severe hypotonia, ataxia, dysarthria, symptoms from the orofacial area (dysphagia, drooling) as well as with altered consciousness. Recovery is slow and usually not full with the persistent symptoms of cerebellar ataxia, dysarthria, dystonic and choreiform movements.

On the Wegener granulomatosis associated region on chromosome 6p21.3.

BACKGROUND: Wegener granulomatosis (WG) belongs to the heterogeneous group of systemic vasculitides. The multifactorial pathophysiology of WG is supposedly caused by yet unknown environmental influence(s) on the basis of genetic predisposition. The presence of anti-neutrophil cytoplasmic antibodies (ANCA) in the plasma of patients and genetic involvement of the human leukocyte antigen system reflect an autoimmune background of the disease. Strong associations were revealed with WG by markers located in the major histocompatibility complex class II (MHC II) region in the vicinity of human leukocyte antigen (HLA)-DPB1 and the retinoid X receptor B (RXRB) loci. In order to define the involvement of the 6p21.3 region in WG in more detail this previous population-based association study was expanded here to the respective 3.6 megabase encompassing this region on chromosome 6. The RXRB gene was analysed as well as a splice-site variation of the butyrophilin-like (BTNL2) gene which is also located within the respective region. The latter polymorphism has been evaluated here as it appears as a HLA independent susceptibility factor in another granulomatous disorder, sarcoidosis. METHODS: 150-180 German WG patients and a corresponding cohort of healthy controls (n = 100-261) were used in a two-step study. A panel of 94 microsatellites was designed for the initial step using a DNA pooling approach. Markers with significantly differing allele frequencies between patient and control pools were individually genotyped. The RXRB gene was analysed for single strand conformation polymorphisms (SSCP) and restriction fragment length polymorphisms (RFLP). The splice-site polymorphism in the BTNL2 gene was also investigated by RFLP analysis. RESULTS: A previously investigated microsatellite (#1.0.3.7, Santa Cruz genome browser (UCSC) May 2004 Freeze localisation: chr6:31257596-34999883), which was used as a positive control, remained associated throughout the whole two-step approach. Yet, no additional evidence for association of other microsatellite markers was found in the entire investigated region. Analysis of the RXRB gene located in the WG associated region revealed associations of two variations (rs10548957 pallelic = 0.02 and rs6531 pallelic = 5.20 x 10-5, OR = 1.88). Several alleles of markers located between HLA-DPB1, SNP rs6531 and microsatellite 1.0.3.7 showed linkage disequilibrium with r2 values exceeding 0.10. Significant differences were not demonstrable for the sarcoidosis associated splice-site variation (rs2076530 pallelic = 0.80) in our WG cohort. CONCLUSION: Since a microsatellite flanking the RXRB gene and two intragenic polymorphisms are associated significantly with WG on chromosome 6p21.3, further investigations should be focussed on extensive fine-mapping in this region by densely mapping with additional markers such as SNPs. This strategy may reveal even deeper insights into the genetic contributions of the respective region for the pathogenesis of WG.