Thousand and one amino-acid kinase 1 (TAOK1) encodes the MAP3K protein kinase TAO1, which has recently been displayed to be essential for neuronal maturation and cortical differentiation during early ...brain development. Heterozygous variants in TAOK1 have been reported in children with neurodevelopmental disorders, with or without macrocephaly, hypotonia and mild dysmorphic traits. Literature reports lack evidence of neuronal migration disorders in TAOK1 patients, although studies in animal models suggest this possibility.
We provide a clinical description of a child with a neurodevelopmental disorder due to a novel TAOK1 truncating variant, whose brain magnetic resonance imaging displays periventricular nodular heterotopia.
To our knowledge, this is the first report of a neuronal migration disorder in a patient with a TAOK1-related neurodevelopmental disorder, thus supporting the hypothesized pathogenic mechanisms of TAOK1 defects.
We aimed to report on previously unappreciated clinical features associated with
-related intellectual disability (ID) syndrome, a rare neurodevelopmental disorder characterized by global ...developmental delay, intellectual disability, and language delay, with or without autistic features.
We performed whole-exome sequencing (WES) to molecularly characterize an individual presenting with ID, epilepsy, autism spectrum disorder, behavioral problems, and facial dysmorphisms as major features.
WES allowed us to identify a previously unreported
splice site variant, c.1429-1G>T (NM_032682.6), in the
gene (OMIM
605515) as the causative event underlying the phenotype. Clinical reassessment of the patient and revision of the literature allowed us to refine the phenotype associated with
haploinsufficiency, including hyperkinetic movement disorder and flat angiomas as associated features. Interestingly, the patient also has an asymmetric face and choanal atresia and a novel
variant of the
gene.
We suggest that
-related ID syndrome may also predispose to the development of hyperkinetic movement disorders and flat angiomas. These features could therefore require specific management of this condition.
Basel-Vanagaite-Smirin-Yosef syndrome (BVSYS) is an extremely rare autosomal recessive genetic disorder caused by variants in the
MED25
gene. It is characterized by severe developmental delay and ...variable craniofacial, neurological, ocular, and cardiac anomalies. Since 2015, through whole exome sequencing, 20 patients have been described with common clinical features and biallelic variants in
MED25
, leading to a better definition of the phenotype associated with BVSYS. We report two young sisters, born to consanguineous parents, presenting with intellectual disability, neurological findings, and dysmorphic features typical of BVSYS, and also with bilateral perisylvian polymicrogyria. The younger sister died at the age of 1 year without autoptic examination. Whole exome sequencing detected a homozygous frameshift variant in the
MED25
gene: NM_030973.3:c.1778_1779delAG, p.(Gln593Argfs). This report further delineates the most common clinical features of BVSYS and points to polymicrogyria as a distinctive neuroradiological feature of this syndrome.
Split Hand-Foot Malformation (SHFM) is a congenital limb defect characterized by a median cleft of the hands and/or feet due to the absence/hypoplasia of the central rays. It may occur as part of a ...syndromic condition or as an isolated malformation. The most common of the six genetic loci identified for this condition is correlated to SHFM1 and maps in the 7q21q22 region. SHFM1 is characterized by autosomal dominant transmission, incomplete penetrance and variable expressivity. Associated features often include hearing loss, intellectual disability/developmental delay and craniofacial abnormalities. Disruption of the DLX5/DLX6 genes, mapping within the SHFM1 locus, is now known to be responsible for the phenotype. Through SNP array, we analyzed a patient affected by SHFM1 associated with deafness and an abnormality of the inner ear (incomplete partition type I); we identified a deletion in 7q21, not involving the DLX5/6 genes, but including exons 15 and 17 of DYNC1I1, known to act as exonic enhancers (eExons) of the DLX5/6 genes. We further demonstrated the role of DYNC1I1 eExons in regulating DLX5/6 expression by means of showing a reduced expression of the DLX5/6 genes through RT-PCR in a patient-derived lymphoblastoid cell line. Furthermore, our data and a review of published cases do not support the hypothesis that DLX5/6 are imprinted in humans. This work is an example of how the disruption of regulatory elements can be responsible for congenital malformations.
One of the recently described syndromes emerging from the massive study of cohorts of undiagnosed patients with autism spectrum disorders (ASD) and syndromic intellectual disability (ID) is ...White-Sutton syndrome (WHSUS) (MIM #616364), caused by variants in the
gene (MIM *614787), located on the long arm of chromosome 1 (1q21.3). So far, more than 50 individuals have been reported worldwide, although phenotypic features and natural history have not been exhaustively characterized yet. The phenotypic spectrum of the WHSUS is broad and includes moderate to severe ID, microcephaly, variable cerebral malformations, short stature, brachydactyly, visual abnormalities, sensorineural hearing loss, hypotonia, sleep difficulties, autistic features, self-injurious behaviour, feeding difficulties, gastroesophageal reflux, and other less frequent features. Here, we report the case of a girl with microcephaly, brain malformations, developmental delay (DD), peripheral polyneuropathy, and adducted thumb-a remarkable clinical feature in the first years of life-and heterozygous for a previously unreported, de novo splicing variant in
. This report contributes to strengthen and expand the knowledge of the clinical spectrum of WHSUS, pointing out the importance of less frequent clinical signs as diagnostic handles in suspecting this condition.
We report on two siblings suffering from different pathogenic conditions, born to consanguineous parents. A multigene panel for brain malformations and microcephaly identified the homozygous splicing ...variant NM_005886.3:c.1416+1del in the
gene in the older sister. On the other hand, exome sequencing revealed the homozygous frameshift variant NM_005245.4:c.9729del in the
gene in the younger sister, who had a more complex phenotype: in addition to bilateral anophthalmia and heart defects, she showed a right split foot with 4 toes, 5 metacarpals, second toe duplication and preaxial polydactyly on the right hand. These features have been never reported before in patients with pathogenic
variants and support the role of this gene in the development of limb buds. Notably, each parent was heterozygous for both of these variants, which were ultra-rare and rare, respectively. This study raises awareness about the value of using whole exome/genome sequencing rather than targeted gene panels when testing affected offspring born to consanguineous couples. In this way, exomic data from the parents are also made available for carrier screening, to identify heterozygous pathogenetic and likely pathogenetic variants in genes responsible for other recessive conditions, which may pose a risk for subsequent pregnancies.
Congenital disorders of glycosylation are a continuously expanding group of monogenic disorders of glycoprotein and glycolipid glycan biosynthesis. These disorders mostly manifest with multisystem ...involvement. Individuals with ALG8‐CDG commonly present with hypotonia, protein‐losing enteropathy, and hepatic involvement. Here, we describe seven unreported individuals diagnosed with ALG8‐CDG based on biochemical and molecular testing and we identify nine novel variants in ALG8, bringing the total to 26 individuals with ALG8‐CDG in the medical literature. In addition to the typical multisystem involvement documented in ALG8‐CDG, our cohort includes the two oldest patients reported and further expands the phenotype of ALG8‐CDG to include stable intellectual disability, autism spectrum disorder and other neuropsychiatric symptoms. We further expand the clinical features in a variety of organ systems including ocular, musculoskeletal, dermatologic, endocrine, and cardiac abnormalities and suggest a comprehensive evaluation and monitoring strategy to improve clinical management.
Cranio‐lenticulo‐sutural dysplasia (CLSD; MIM 607812) is a rare or underdiagnosed condition, as only two families have been reported. The original family (Boyadjiev et al., Human Genetics, 2003, 113, ...1–9 and Boyadjiev et al., Nature Genetics, 2006, 38, 1192–1197) showed recessive inheritance of the condition with a biallelic SEC23A missense variant in affected individuals. In contrast, another child with sporadic CLSD had a monoallelic SEC23A variant inherited from the reportedly unaffected father (Boyadjiev et al., Clinical Genetics, 2011, 80, 169–176), raising questions on possible digenism. Here, we report a 2‐month‐old boy seen because of large fontanels with wide cranial sutures, a large forehead, hypertelorism, a thin nose, a high arched palate, and micrognathia. His mother was clinically unremarkable, while his father had a history of large fontanels in infancy who had closed only around age 10 years; he also had a large forehead, hypertelorism, a thin, beaked nose and was operated for bilateral glaucoma with exfoliation of the lens capsule. Trio genome sequencing and familial segregation revealed a monoallelic c.1795G > A transition in SEC23A that was de novo in the father and transmitted to the proband. The variant predicts a nonconservative substitution (p.E599K) in an ultra‐conserved residue that is seen in 3D models of yeast SEC23 to be involved in direct binding between SEC23 and SAR1 subunits of the coat protein complex II coat. This observation confirms the link between SEC23A variants and CLSD but suggests that in addition to the recessive inheritance described in the original family, SEC23A variants may result in dominant inheritance of CLSD, possibly by a dominant‐negative disruptive effect on the SEC23 multimer.
EAST/SeSAME syndrome is a rare disease affecting the Central Nervous System (CNS), inner ear, and kidney. The syndrome is due to loss-of-function mutations in the KCNJ10 gene encoding the ...inward-rectifying potassium channel Kir4.1. EAST/SeSAME syndrome is mainly diagnosed during childhood with a tonic-clonic seizure being the usual first symptom. Due to a limited number of patients and recent identification of the disease, few data are available on the clinical progress of this disease in adulthood. In particular, neurologic and nephrological outcomes have not been reported. We present a case series of 4 adult patients harbouring homozygous missense mutation p.Ala167Val and homozygous frameshift mutations p.Asn232Glnfs*14 and p.Gly275Valfs*7. Effects of these mutations were predicted by in silico modelling and bioinformatic tools. Patients with truncating mutations were associated with more severe outcomes, both in tubulopathy severity and neurological symptomatology. Conversely, either missense or truncating mutations were correlated with similar severity of epilepsy, with a long free-of-event period up to 20 years old. No eGFR decline was documented. Modelling predicted that truncating mutations lead to complete Kir4.1 dysfunction. Finally, all patients had a mild increase in urinary protein excretion. Our study indicates that the prognosis of patients suffering from EAST/SeSAME syndrome is related to the severity of the mutation causing the disease. As predicted by in silico modelling, truncating mutations of KCNJ10 are associated with more severe disease, with recurrence of symptomatic hypokalemia and more severe neurological phenotype. The type of mutation should be considered for the therapy tailored to patients' phenotype.
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