@article {128, title = {Phenotypic expansion in KIF1A-related dominant disorders: A description of novel variants and review of published cases.}, journal = {Hum Mutat}, volume = {41}, year = {2020}, month = {2020 12}, pages = {2094-2104}, abstract = {

KIF1A is a molecular motor for membrane-bound cargo important to the development and survival of sensory neurons. KIF1A dysfunction has been associated with several Mendelian disorders with a spectrum of overlapping phenotypes, ranging from spastic paraplegia to intellectual disability. We present a novel pathogenic in-frame deletion in the KIF1A molecular motor domain inherited by two affected siblings from an unaffected mother with apparent germline mosaicism. We identified eight additional cases with heterozygous, pathogenic KIF1A variants ascertained from a local data lake. Our data provide evidence for the expansion of KIF1A-associated phenotypes to include hip subluxation and dystonia~as well as phenotypes observed in only a single case: gelastic cataplexy, coxa valga, and double collecting system. We review the literature and suggest that KIF1A dysfunction is better understood as a single neuromuscular disorder with variable involvement of other organ systems than a set of discrete disorders converging at a single locus.

}, issn = {1098-1004}, doi = {10.1002/humu.24118}, author = {Montenegro-Garreaud, Ximena and Hansen, Adam W and Khayat, Michael M and Chander, Varuna and Grochowski, Christopher M and Jiang, Yunyun and Li, He and Mitani, Tadahiro and Kessler, Elena and Jayaseelan, Joy and Shen, Hua and Gezdirici, Alper and Pehlivan, Davut and Meng, Qingchang and Rosenfeld, Jill A and Jhangiani, Shalini N and Madan-Khetarpal, Suneeta and Scott, Daryl A and Abarca-Barriga, Hugo and Trubnykova, Milana and Gingras, Marie-Claude and Muzny, Donna M and Posey, Jennifer E and Liu, Pengfei and Lupski, James R and Gibbs, Richard A} } @article {76, title = {Biallelic and De Novo Variants in DONSON Reveal a Clinical Spectrum of Cell Cycle-opathies with Microcephaly, Dwarfism and Skeletal Abnormalities.}, journal = {Am J Med Genet A}, volume = {179}, year = {2019}, month = {2019 Oct}, pages = {2056-2066}, abstract = {

Co-occurrence of primordial dwarfism and microcephaly together with particular skeletal findings are seen in a wide range of Mendelian syndromes including microcephaly micromelia syndrome (MMS, OMIM 251230), microcephaly, short stature, and limb abnormalities (MISSLA, OMIM 617604), and microcephalic primordial dwarfisms (MPDs). Genes associated with these syndromes encode proteins that have crucial roles in DNA replication or in other critical steps of the cell cycle that link DNA replication to cell division. We identified four unrelated families with five affected individuals having biallelic or de novo variants in DONSON presenting with a core phenotype of severe short stature (z score < -3 SD), additional skeletal abnormalities, and microcephaly. Two apparently unrelated families with identical homozygous c.631C > T p.(Arg211Cys) variant had clinical features typical of Meier-Gorlin syndrome (MGS), while two siblings with compound heterozygous c.346delG p.(Asp116Ile*62) and c.1349A > G p.(Lys450Arg) variants presented with Seckel-like phenotype. We also identified a de novo c.683G > T p.(Trp228Leu) variant in DONSON in a patient with prominent micrognathia, short stature and hypoplastic femur and tibia, clinically diagnosed with Femoral-Facial syndrome (FFS, OMIM 134780). Biallelic variants in DONSON have been recently described in individuals with microcephalic dwarfism. These studies also demonstrated that DONSON has an essential conserved role in the cell cycle. Here we describe novel biallelic and de novo variants that are associated with MGS, Seckel-like phenotype and FFS, the last of which has not been associated with any disease gene to date.

}, issn = {1552-4833}, doi = {10.1002/ajmg.a.61315}, author = {Karaca, Ender and Posey, Jennifer E and Bostwick, Bret and Liu, Pengfei and Gezdirici, Alper and Yesil, Gozde and Coban Akdemir, Zeynep and Bayram, Yavuz and Harms, Frederike L and Meinecke, Peter and Alawi, Malik and Bacino, Carlos A and Sutton, V Reid and Kort{\"u}m, Fanny and Lupski, James R} } @article {77, title = {Biallelic CACNA2D2 variants in epileptic encephalopathy and cerebellar atrophy.}, journal = {Ann Clin Transl Neurol}, volume = {6}, year = {2019}, month = {2019 Aug}, pages = {1395-1406}, abstract = {

OBJECTIVE: To characterize the molecular and clinical phenotypic basis of developmental and epileptic encephalopathies caused by rare biallelic variants in CACNA2D2.

METHODS: Two affected individuals from a family with clinical features of early onset epileptic encephalopathy were recruited for exome sequencing at the Centers for Mendelian Genomics to identify their molecular diagnosis. GeneMatcher facilitated identification of a second family with a shared candidate disease gene identified through clinical gene panel-based testing.

RESULTS: Rare biallelic CACNA2D2 variants have been previously reported in three families with developmental and epileptic encephalopathy, and one family with congenital ataxia. We identified three individuals in two unrelated families with novel homozygous rare variants in CACNA2D2 with clinical features of developmental and epileptic encephalopathy and cerebellar atrophy. Family 1 includes two affected siblings with a likely damaging homozygous rare missense variant c.1778G>C; p.(Arg593Pro) in CACNA2D2. Family 2 includes a proband with a homozygous rare nonsense variant c.485_486del; p.(Tyr162Ter) in CACNA2D2. We compared clinical and molecular findings from all nine individuals reported to date and note that cerebellar atrophy is shared among all.

INTERPRETATION: Our study supports the candidacy of CACNA2D2 as a disease gene associated with a phenotypic spectrum of neurological disease that include features of developmental and epileptic encephalopathy, ataxia, and cerebellar atrophy. Age at presentation may affect apparent penetrance of neurogenetic trait manifestations and of a particular clinical neurological endophenotype, for example, seizures or ataxia.

}, issn = {2328-9503}, doi = {10.1002/acn3.50824}, author = {Punetha, Jaya and Karaca, Ender and Gezdirici, Alper and Lamont, Ryan E and Pehlivan, Davut and Marafi, Dana and Appendino, Juan P and Hunter, Jill V and Akdemir, Zeynep C and Fatih, Jawid M and Jhangiani, Shalini N and Gibbs, Richard A and Innes, A Micheil and Posey, Jennifer E and Lupski, James R} }