GATAD2B-associated neurodevelopmental disorder (GAND)

Inspired by a patient

Shieh C, Jones N, Vanle B, Au M, Huang AY, Silva APG, Lee H, Douine ED, Otero MG, Choi A, Grand K, Taff IP, Delgado MR, Hajianpour MJ, Seeley A, Rohena L, Vernon H, Gripp KW, Vergano SA, Mahida S, Naidu S, Sousa AB, Wain KE, Challman TD, Beek G, Basel D, Ranells J, Smith R, Yusupov R, Freckmann ML, Ohden L, Davis-Keppen L, Chitayat D, Dowling JJ, Finkel R, Dauber A, Spillmann R, Pena LDM; Undiagnosed Diseases Network; Metcalfe K, Splitt M, Lachlan K, McKee SA, Hurst J, Fitzpatrick DR, Morton JEV, Cox H, Venkateswaran S, Young JI, Marsh ED, Nelson SF, Martinez JA, Graham JM Jr, Kini U, Mackay JP, Pierson TM. GATAD2B-associated neurodevelopmental disorder (GAND): clinical and molecular insights into a NuRD-related disorder. Genet Med. 2020 May;22(5):878-888. doi: 10.1038/s41436-019-0747-z. Epub 2020 Jan 17. Erratum in: Genet Med. 2020 Apr;22(4):822. doi: 10.1038/s41436-020-0760-2. PMID: 31949314; PMCID: PMC7920571.

Abstract

Purpose: Determination of genotypic/phenotypic features of GATAD2B-associated neurodevelopmental disorder (GAND).

Methods: Fifty GAND subjects were evaluated to determine consistent genotypic/phenotypic features. Immunoprecipitation assays utilizing in vitro transcription-translation products were used to evaluate GATAD2B missense variants' ability to interact with binding partners within the nucleosome remodeling and deacetylase (NuRD) complex.

Results: Subjects had clinical findings that included macrocephaly, hypotonia, intellectual disability, neonatal feeding issues, polyhydramnios, apraxia of speech, epilepsy, and bicuspid aortic valves. Forty-one novelGATAD2B variants were identified with multiple variant types (nonsense, truncating frameshift, splice-site variants, deletions, and missense). Seven subjects were identified with missense variants that localized within two conserved region domains (CR1 or CR2) of the GATAD2B protein. Immunoprecipitation assays revealed several of these missense variants disrupted GATAD2B interactions with its NuRD complex binding partners.

Conclusions: A consistent GAND phenotype was caused by a range of genetic variants in GATAD2B that include loss-of-function and missense subtypes. Missense variants were present in conserved region domains that disrupted assembly of NuRD complex proteins. GAND's clinical phenotype had substantial clinical overlap with other disorders associated with the NuRD complex that involve CHD3 and CHD4, with clinical features of hypotonia, intellectual disability, cardiac defects, childhood apraxia of speech, and macrocephaly.

Vera G, Sorlin A, Delplancq G, Lecoquierre F, Brasseur-Daudruy M, Petit F, Smol T, Ziegler A, Bonneau D, Colin E, Mercier S, Cogné B, Bézieau S, Edery P, Lesca G, Chatron N, Sabatier I, Duban-Bedu B, Colson C, Piton A, Durand B, Capri Y, Perrin L, Wiesener A, Zweier C, Maroofian R, Carroll CJ, Galehdari H, Mazaheri N, Callewaert B, Giulianno F, Zaafrane-Khachnaoui K, Buchert-Lo R, Haack T, Magg J, Rieß A, Blandfort M, Waldmüller S, Horber V, Leonardi E, Polli R, Turolla L, Murgia A, Frebourg T, Lebre AS, Nicolas G, Saugier-Veber P, Guerrot AM. Clinical and molecular description of 19 patients with GATAD2B-Associated Neurodevelopmental Disorder (GAND). Eur J Med Genet. 2020 Oct;63(10):104004. doi: 10.1016/j.ejmg.2020.104004. Epub 2020 Jul 17. PMID: 32688057.

Abstract

De novo pathogenic variants in the GATAD2B gene have been associated with a syndromic neurodevelopmental disorder (GAND) characterized by severe intellectual disability (ID), impaired speech, childhood hypotonia, and dysmorphic features. Since its first description in 2013, nine patients have been reported in case reports and a series of 50 patients was recently published, which is consistent with the relative frequency of GATAD2B pathogenic variants in public databases. We report the detailed phenotype of 19 patients from various ethnic backgrounds with confirmed pathogenic GATAD2B variants including intragenic deletions. All individuals presented developmental delay with a median age of 2.5 years for independent walking and of 3 years for first spoken words. GATAD2B variant carriers showed very little subsequent speech progress, two patients over 30 years of age remaining non-verbal. ID was mostly moderate to severe, with one profound and one mild case, which shows a wider spectrum of disease severity than previously reported. We confirm macrocephaly as a major feature in GAND (53%). Most common dysmorphic features included broad forehead, deeply set eyes, hypertelorism, wide nasal base, and pointed chin. Conversely, prenatal abnormalities, non-cerebral malformations, epilepsy, and autistic behavior were uncommon. Other features included feeding difficulties, behavioral abnormalities, and unspecific abnormalities on brain MRI. Improving our knowledge of the clinical phenotype is essential for correct interpretation of the molecular results and accurate patient management.

Abad C, Robayo MC, Muñiz-Moreno MDM, Bernardi MT, Otero MG, Kosanovic C, Griswold AJ, Pierson TM, Walz K, Young JI. Gatad2b, associated with the neurodevelopmental syndrome GAND, plays a critical role in neurodevelopment and cortical patterning. Transl Psychiatry. 2024 Jan 18;14(1):33. doi: 10.1038/s41398-023-02678-x. PMID: 38238293; PMCID: PMC10796954.

Abstract

GATAD2B (GATA zinc finger domain containing 2B) variants are associated with the neurodevelopmental syndrome GAND, characterized by intellectual disability (ID), infantile hypotonia, apraxia of speech, epilepsy, macrocephaly and distinct facial features. GATAD2B encodes for a subunit of the Nucleosome Remodeling and Histone Deacetylase (NuRD) complex. NuRD controls transcriptional programs critical for proper neurodevelopment by coupling histone deacetylase with ATP-dependent chromatin remodeling activity. To study mechanisms of pathogenesis for GAND, we characterized a mouse model harboring an inactivating mutation in Gatad2b. Homozygous Gatad2b mutants die perinatally, while haploinsufficient Gatad2b mice exhibit behavioral abnormalities resembling the clinical features of GAND patients. We also observed abnormal cortical patterning, and cellular proportions and cell-specific alterations in the developmental transcriptome in these mice. scRNAseq of embryonic cortex indicated misexpression of genes key for corticogenesis and associated with neurodevelopmental syndromes such as Bcl11b, Nfia and H3f3b and Sox5. These data suggest a crucial role for Gatad2b in brain development.