AHDC1 [1] is a gene, changes in which are found through clinical studies to cause an array of symptoms in affected children known collectively as Xia-Gibbs Syndrome, [2] [3] including global developmental delay, global hypotonia, obstructive sleep apnoea and seizures.
In 2014, a human genetic disorder (Xia-Gibbs Syndrome) caused by de novo mutations in AHDC1 was discovered through whole-exome sequencing. [4] Four patients were identified in the paper which recorded the initial discovery and their clinical features were reported, including global developmental delay, hypotonia, obstructive sleep apnea, intellectual disability and seizures. The publication of the paper and discovery of the new condition was reported in the media including in Science Daily and in Baylor College of Medicine News. [5] [6] [7] Subsequent research has identified and reported the clinical features of an additional seven patients and there are now known to be twenty confirmed cases. [8]
Kabuki syndrome is a congenital disorder of genetic origin. It affects multiple parts of the body, with varying symptoms and severity, although the most common is the characteristic facial appearance.
Rubinstein–Taybi syndrome (RTS) is a rare genetic condition characterized by short stature, moderate to severe learning difficulties, distinctive facial features, and broad thumbs and first toes. Other features of the disorder vary among affected individuals. These characteristics are caused by a mutation or deletion in the CREBBP gene, located on chromosome 16, and/or the EP300 gene, located on chromosome 22.
Acrocallosal syndrome is an extremely rare autosomal recessive syndrome characterized by corpus callosum agenesis, polydactyly, multiple dysmorphic features, motor and intellectual disabilities, and other symptoms. The syndrome was first described by Albert Schinzel in 1979. Mutations in KIF7 are causative for ACLS, and mutations in GLI3 are associated with a similar syndrome.
Pitt–Hopkins syndrome (PTHS) is a rare genetic disorder characterized by developmental delay, epilepsy, distinctive facial features, and possible intermittent hyperventilation followed by apnea. Pitt–Hopkins syndrome can be marked by intellectual disabilities as well as problems with socializing. It is part of the clinical spectrum of Rett-like syndromes.
Epilepsy-intellectual disability in females also known as PCDH19 gene-related epilepsy or epileptic encephalopathy, early infantile, 9 (EIEE9), is a rare type of epilepsy that affects predominately females and is characterized by clusters of brief seizures, which start in infancy or early childhood, and is occasionally accompanied by varying degrees of cognitive impairment. The striking pattern of onset seizures at a young age, genetic testing and laboratory results, potential developmental delays or developmental regression and associated disorders, eases diagnosis.
Bohring–Opitz syndrome (BOS) is a medical syndrome caused by a mutation in the ASXL1 gene.
Xia-Gibbs Syndrome, is genetic disorder caused by a heterozygous mutation in the AHDC1 gene on chromosome 1p36.
ZTTK syndrome is a rare multisystem disease caused in humans by a genetic mutation of the SON gene. Common symptoms include developmental delay and often mild to severe intellectual disability.
Bainbridge–Ropers syndrome was first identified in 2013 and is characterized by failure to thrive, feeding problems, hypotonia, intellectual disabilities, autism, postnatal growth delay, abnormal facial features such as arched eyebrows, anteverted nares, and delays in language acquisition. BRPS is extremely rare worldwide; more than thirty cases of BRPS have been reported abroad, and four cases have been reported in China.
Xp11.2 duplication is a genomic variation marked by the duplication of an X chromosome region on the short arm p at position 11.2, defined by standard karyotyping (G-banding). This gene-rich, rearrangement prone region can be further divided into three loci - Xp11.21, Xp11.22 and Xp11.23. The duplication could involve any combination of these three loci. While the length of the duplication can vary from 0.5Mb to 55 Mb, most duplications measure about 4.5Mb and typically occur in the region of 11.22-11.23. Most affected females show preferential activation of the duplicated X chromosome. Features of affected individuals vary significantly, even among members of the same family. The Xp11.2 duplication can be 'silent' - presenting no obvious symptoms in carriers - which is known from the asymptomatic parents of affected children carrying the duplication. The common symptoms include intellectual disabilities, speech delay and learning difficulties, while in rare cases, children have seizures and a recognizable brain wave pattern when assessed by EEG (electroencephalography).
SYT1-associated neurodevelopmental disorder, also known as Baker-Gordon Syndrome, is a rare genetic disorder caused by mutations in the synaptotagmin-1 (SYT1) gene.
DeSanto-Shinawi (DESSH) syndrome is a rare genetic disorder caused by genetic variations (mutations) in a gene called WW Domain-Containing Adaptor with Coiled-coil Region. The condition was first described in 2015 in six individuals. The prevalence of DESSH syndrome is unknown at this time, but 25 individuals have been so far described in the medical literature. However, many other individuals with this condition are being studied and characterized. With the increasing utilization of exome and whole genome sequencing, it is anticipated that many more individuals to be identified.
SYNGAP1-related intellectual disability is a monogenetic developmental and epileptic encephalopathy that affects the central nervous system. Symptoms include intellectual disability, epilepsy, autism, sensory processing deficits, hypotonia and unstable gait.
Jordan's Syndrome (JS) or PPP2R5D-related intellectual disability is a rare autosomal dominant neurodevelopmental disorder caused by de novo mutations in the PPP2R5D gene. It is characterized by hypotonia, intellectual disability, and macrocephaly. Children with JS may also have epilepsy or meet criteria for diagnosis with autism spectrum disorder.
Multiple congenital anomalies-hypotonia-seizures syndrome is a rare multi-systemic genetic disorder which is characterized by developmental delay, seizures, hypotonia and heart, urinary, and gastrointestinal abnormalities.
PURA syndrome, also known as PURA-related neurodevelopmental disorder, is a rare novel genetic disorder which is characterized by developmental and speech delay, neo-natal hypotonia, failure to thrive, excessive sleepiness, epilepsy, and other anomalies.
HNRNPH2-related disorder is considered as a neurodevelopmental disorder (NDD) caused by heterozygous mutation in the HNRNPH2 gene on the chromosome Xq22.
CHAMP1-associated intellectual disability syndrome, also known as autosomal dominant intellectual disability type 40, is a rare genetic disorder characterized by intellectual disabilities, developmental delays, facial dysmorphisms, and other anomalies.
Autosomal dominant intellectual disability-craniofacial anomalies-cardiac defects syndrome is a rare genetic disorder which is characterized by multi-systemic symptoms primarily affecting the intellect and post-natal development.
Severe intellectual disability-progressive spastic diplegia syndrome is a rare novel genetic disorder characterized by severe intellectual disabilities, ataxia, craniofacial dysmorphisms, and muscle spasticity. It is a type of autosomal dominant syndromic intellectual disability.