Details

Autor(en) / Beteiligte

• Radley, Jessica A.
• O'Sullivan, Rory B.G.
• Turton, Sarah E.
• Cox, Helen
• Vogt, Julie
• Morton, Jenny
• Jones, Elizabeth
• Smithson, Sarah
• Lachlan, Katherine
• Rankin, Julia
• Clayton‐Smith, Jill
• Willoughby, Josh
• Elmslie, Frances F.
• Sansbury, Francis H.
• Cooper, Nicola
• Balasubramanian, Meena

Titel

Deep phenotyping of 14 new patients with IQSEC2 variants, including monozygotic twins of discordant phenotype

Ist Teil von

• Clinical genetics, 2019-04, Vol.95 (4), p.496-506

Ort / Verlag

Oxford, UK: Blackwell Publishing Ltd

Erscheinungsjahr

2019

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• Whole‐exome sequencing has established IQSEC2 as a neurodevelopmental disability gene. The IQSEC2 variant phenotype includes developmental delay, intellectual disability, epilepsy, hypotonia, autism, developmental regression, microcephaly and stereotypies but is yet to be fully described. Presented here are 14 new patients with IQSEC2 variants. In addition to the established features, we observed: gait ataxia in 7 of 9 (77.8%), drooling in 9 of 14 (64.2%), early feeding difficulties in 7 of 14 (50%), structural brain abnormalities in 6 of 13 (46.2%), brachycephaly in 5 of 14 (35.7%), and scoliosis and paroxysms of laughter each in 4 of 14 (28.6%). We suggest that these are features of the IQSEC2‐related disorder. Gastrostomy requirement, plagiocephaly, strabismus and cortical blindness, each seen in 2 of 14 (14.3%), may also be associated. Shared facial features were noted in 8 of 14 patients, and shared hair patterning was identified in 5 of 14 patients. This study further delineates the IQSEC2 phenotypic spectrum and supports the notion of an emerging IQSEC2 syndrome. We draw parallels between the IQSEC2‐related disorder and the Angelman‐/Rett‐/Pitt‐Hopkins syndrome group of conditions and recommend the addition of IQSEC2 to epilepsy and developmental delay gene panels. We observed discordant phenotypes in monozygotic twins and apparent gonadal mosaicism, which has implications for recurrence risk counselling in the IQSEC2‐related disorder. Features found in patients with IQSEC2 variants.