CDK13-related disorder | |
---|---|
Other names | Congenital heart defects, dysmorphic facial features and intellectual developmental disorder (CHDFIDD), [1] CDK13-related CHDFIDD [1] |
Typical facial appearance of an individual with CDK13-related disorder | |
Specialty | Medical genetics |
Symptoms | Congenital heart defects, intellectual disability, characteristic facial features, gastrointestinal dysmotility [2] |
Causes | Genetic (autosomal dominant mutation in CDK13 ) [3] |
Diagnostic method | Genetic testing [2] |
Treatment | Gastroprokinetic medication, gastrostomy, speech therapy, assistive communication devices [2] |
Prognosis | Not yet certain. A few patients in mid-adulthood identified. [3] |
Frequency | Not yet known. At least 44 individuals diagnosed as of January 2019 [update] . [3] |
CDK13-related disorder, also known as congenital heart defects, dysmorphic facial features and intellectual developmental disorder (CHDFIDD), is a very rare autosomal dominant genetic condition characterised by congenital heart defects, intellectual disability and characteristic facial features. Those affected typically have motor and language delays, low muscle tone and gastrointestinal dysmotility. Facial features include a wide nasal bridge, widely-spaced eyes, prominent, low-set ears, a flat nose tip and a small mouth. [2] [3] Less common features include congenital spinal abnormalities, hearing loss or seizures. [2] [4]
The syndrome is caused by a mutation in the CDK13 gene, which encodes the protein cyclin-dependent kinase 13. Cyclin-dependent kinases are protein kinases, which are critical for regulating DNA transcription for cell differentiation. CDK13 promotes expression of genes involved in various developmental processes, and these processes are disrupted or not completed when the gene is mutated. [1] [3] [5] The syndrome is diagnosed when genetic testing confirms a mutation in CDK13. [2]
Treatment centres around the symptoms. Medication or, in severe cases, gastrostomy can be used for the gastrointestinal dysmotility. [2] [3] [6] Speech therapy as early as possible or assistive communication devices can aid language development. [1] [2] [7] The prognosis is not certain as of yet, due to the lack of known patients, however a few patients in mid-adulthood have been identified. [3]
As of January 2019 [update] , at least 44 individuals with the condition had been identified and studied. [3] Mutations in CDK13 were first identified as pathogenic in a 2016 cohort study, [3] [8] and the disorder was first outlined by Bostwick et al. in 2017, who also established the name CHDFIDD. [1]
Most individuals with CDK13-related disorder have congenital heart defects, typically an atrial or ventricular septal defect. [2] [3] [4]
Those with the disorder typically have a characteristic facial appearance which includes a wide nasal bridge, widely-spaced eyes, upslanted eyelids, epicanthic folds, high-arched eyebrows, prominent, low-set ears, a flat nose tip and a small mouth with a small upper lip. [1] [2] [4] In some of those affected, the syndrome causes curly hair. [2] [4] The facial appearance has been noted to resemble that of Kabuki syndrome. [1] [2]
The syndrome typically results in intellectual disability, including motor and language delays. [2] [3] [4] Some individuals have had agenesis of the corpus callosum or aplasia of the cerebellar vermis. [1] [2] [3] This can sometimes manifest with symptoms of autism spectrum disorder. [2] [3] [4] Low muscle tone and strabismus are also common. [1] [2] A few patients have had microcephaly and seizures. [2] [3] [4]
Affected individuals tend to have dysautonomic symptoms of gastrointestinal dysmotility, which can include gastroesophageal reflux, constipation and trouble swallowing. [2] [3] [4] A few of those affected have had ear problems such as sensorineural hearing loss or recurrent ear infections, [4] and a few individuals have had congenital spinal abnormalities including fused vertebrae or spina bifida as well as scoliosis. [2] [3] [4]
The syndrome is caused by a mutation in one of the two copies of the gene CDK13 , which encodes the protein cyclin dependent kinase 13. Cyclin-dependent kinases are protein kinases, which have an essential function in the cell cycle and the transcription of DNA. This is specifically through protein phosphorylation, which functions to turn off or on certain proteins, allowing cell differentiation and the progression of the normal developmental processes. A mutation in one of the two copies of these genes results in some proteins not being formed correctly and therefore some developmental processes being disrupted or not completed. [3] Specifically, CDK13 appears to phosphorylate RNA polymerase II and enable it to carry out transcription of genes on DNA. It appears to largely do this when RNA polymerase II is transcribing certain genes involved in promoting cell development. [1] [3] [5]
Mutations in CDK13 that have been identified in individuals with this disorder have mostly been missense mutations (single amino acid changes) that have changed the amino acid structure of the otherwise highly conserved (little-changed) protein kinase domain of the gene, leading to structural changes that affect the operation of this critical protein. [2] [3] The most commonly identified mutations are those that change the 842nd amino acid of the protein, an asparagine (Asn), to a serine (Ser) or an aspartic acid (Asp), [1] [3] [7] but many others have been identified. [7] Different mutations, depending on how much they reduce the kinase functionality of the gene, have resulted in different severities of the syndrome. Those with total activity-eliminating mutations have, for example, had microcephaly. [4]
Mutations in both copies of CDK13 are embryonic lethal in mice. Mice who have had both of their copies of CDK13 knocked out do not survive past the 16th day of embryonic development due to heart failure, as the heart has significantly fewer myocytes and less myocardium, with less expression of myosin. All organs are smaller and less developed, and the embryo is reduced in size. [9]
The condition is generally diagnosed after genetic testing confirms CDK13 as mutated, although the condition may be suspected based on the symptoms. Methods to detect the mutation include whole exome sequencing and panel testing, in which a selection of potential genes involved are sequenced. The mutation can be confirmed by Sanger sequencing. [1] [2] [4]
Treatment centres around the symptoms. Atrial or ventricular septal defects are usually treated with observation but can be surgically corrected in severe cases. Prokinetic medication can be used to promote gastric emptying. [6] If the gastric dysmotility is too severe for adequate intake, a gastrostomy can be performed. [2] [3] [4] Speech therapy as early as possible or assistive communication devices can aid in language development. [1] [2] [7]
The prognosis is not certain as of yet, as most of the individuals discovered and studied have been children, [3] [7] however a few patients in mid-adulthood have been identified. [1] [3] [7]
The prevalence is not yet known, as the disorder was only recently defined. Beginning with Bostwick et al.'s report in 2017, at least 44 individuals with the condition have been identified and studied as of January 2019 [update] . [3]
Mutations in CDK13 were first identified as pathogenic in 2016, when they were identified in 7 individuals from a large cohort of 1,891 patients with congenital heart defects in a study by Sifrim et al. [2] [3] [8] Mutations in CDK13 were then found again in 2017 in 11 individuals from an even larger cohort of 4,293 patients from the UK and Ireland with developmental delay by McRae et al., as part of the UK Deciphering Developmental Disorders (DDD) cohort study. [2] [3] [10]
The disorder was first established and outlined by Bostwick et al, (2017) (9 patients), who also established the term congenital heart defects, dysmorphic facial features and intellectual developmental disorder (CHDFIDD). [1] Later work by Hamilton et al. (2018) (16 patients), [4] Uehara et al. (2018) (3 patients) [6] and van den Akker et al. (2018) (15 patients) [7] identified and studied additional patients. [2] [3]
Kabuki syndrome is a rare 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.
Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored eyes, low-set ears, a short neck, and a small lower jaw. Heart problems may include pulmonary valve stenosis. The breast bone may either protrude or be sunken, while the spine may be abnormally curved. Intelligence is often normal. Complications of NS can include leukemia.
Coffin–Lowry syndrome is a genetic disorder that is X-linked dominant and which causes severe mental problems sometimes associated with abnormalities of growth, cardiac abnormalities, kyphoscoliosis, as well as auditory and visual abnormalities.
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.
Robinow syndrome is an extremely rare genetic disorder characterized by short-limbed dwarfism, abnormalities in the head, face, and external genitalia, as well as vertebral segmentation. The disorder was first described in 1969 by human geneticist Meinhard Robinow, along with physicians Frederic N. Silverman and Hugo D. Smith, in the American Journal of Diseases of Children. By 2002, over 100 cases had been documented and introduced into medical literature.
Larsen syndrome (LS) is a congenital disorder discovered in 1950 by Larsen and associates when they observed dislocation of the large joints and face anomalies in six of their patients. Patients with Larsen syndrome normally present with a variety of symptoms, including congenital anterior dislocation of the knees, dislocation of the hips and elbows, flattened facial appearance, prominent foreheads, and depressed nasal bridges. Larsen syndrome can also cause a variety of cardiovascular and orthopedic abnormalities. This rare disorder is caused by a genetic defect in the gene encoding filamin B, a cytoplasmic protein that is important in regulating the structure and activity of the cytoskeleton. The gene that influences the emergence of Larsen syndrome is found in chromosome region, 3p21.1-14.1, a region containing human type VII collagen gene. Larsen syndrome has recently been described as a mesenchyme disorder that affects the connective tissue of an individual. Autosomal dominant and recessive forms of the disorder have been reported, although most cases are autosomal dominant. Reports have found that in Western societies, Larsen syndrome can be found in one in every 100,000 births, but this is most likely an underestimate because the disorder is frequently unrecognized or misdiagnosed.
22q13 deletion syndrome, known as Phelan–McDermid syndrome (PMS), is a genetic disorder caused by deletions or rearrangements on the q terminal end of chromosome 22. Any abnormal genetic variation in the q13 region that presents with significant manifestations (phenotype) typical of a terminal deletion may be diagnosed as 22q13 deletion syndrome. There is disagreement among researchers as to the exact definition of 22q13 deletion syndrome. The Developmental Synaptopathies Consortium defines PMS as being caused by SHANK3 mutations, a definition that appears to exclude terminal deletions. The requirement to include SHANK3 in the definition is supported by many but not by those who first described 22q13 deletion syndrome.
Aarskog–Scott syndrome (AAS) is a rare disease inherited as X-linked and characterized by short stature, facial abnormalities, skeletal and genital anomalies. This condition mainly affects males, although females may have mild features of the syndrome.
Young–Simpson syndrome (YSS) is a rare congenital disorder with symptoms including hypothyroidism, heart defects, facial dysmorphism, cryptorchidism in males, hypotonia, intellectual disability, and postnatal growth retardation.
FG syndrome (FGS) is a rare genetic syndrome caused by one or more recessive genes located on the X chromosome and causing physical anomalies and developmental delays. FG syndrome was named after the first letters of the surnames of the first patients noted with the disease. First reported by American geneticists John M. Opitz and Elisabeth G. Kaveggia in 1974, its major clinical features include intellectual disability, hyperactivity, hypotonia, and a characteristic facial appearance including macrocephaly.
Wilson-Turner syndrome (WTS), also known as mental retardation X linked syndromic 6 (MRXS6), and mental retardation X linked with gynecomastia and obesity is a congenital condition characterized by intellectual disability and associated with childhood-onset obesity. It is found to be linked to the X chromosome and caused by a mutation in the HDAC8 gene, which is located on the q arm at locus 13.1. Individuals with Wilson–Turner syndrome have a spectrum of physical characteristics including dysmorphic facial features, hypogonadism, and short stature. Females generally have milder phenotypes than males. This disorder affects all demographics equally and is seen in less than one in one million people.
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.
Malpuech facial clefting syndrome, also called Malpuech syndrome or Gypsy type facial clefting syndrome, is a rare congenital syndrome. It is characterized by facial clefting, a caudal appendage, growth deficiency, intellectual and developmental disability, and abnormalities of the renal system (kidneys) and the male genitalia. Abnormalities of the heart, and other skeletal malformations may also be present. The syndrome was initially described by Georges Malpuech and associates in 1983. It is thought to be genetically related to Juberg-Hayward syndrome. Malpuech syndrome has also been considered as part of a spectrum of congenital genetic disorders associated with similar facial, urogenital and skeletal anomalies. Termed "3MC syndrome", this proposed spectrum includes Malpuech, Michels and Mingarelli-Carnevale (OSA) syndromes. Mutations in the COLLEC11 and MASP1 genes are believed to be a cause of these syndromes. The incidence of Malpuech syndrome is unknown. The pattern of inheritance is autosomal recessive, which means a defective (mutated) gene associated with the syndrome is located on an autosome, and the syndrome occurs when two copies of this defective gene are inherited.
Sotos syndrome is a rare genetic disorder characterized by excessive physical growth during the first years of life. Excessive growth often starts in infancy and continues into the early teen years. The disorder may be accompanied by autism, mild intellectual disability, delayed motor, cognitive, and social development, hypotonia, and speech impairments. Children with Sotos syndrome tend to be large at birth and are often taller, heavier, and have relatively large skulls (macrocephaly) than is normal for their age. Signs of the disorder, which vary among individuals, include a disproportionately large skull with a slightly protrusive forehead, large hands and feet, large mandible, hypertelorism, and downslanting eyes. Clumsiness, an awkward gait, and unusual aggressiveness or irritability may also occur.
9q34 deletion syndrome is a rare genetic disorder. Terminal deletions of chromosome 9q34 have been associated with childhood hypotonia, a distinctive facial appearance and developmental disability. The facial features typically described include arched eyebrows, small head circumference, midface hypoplasia, prominent jaw and a pouting lower lip. Individuals with this disease may often have speech impediments, such as speech delays. Other characteristics of this disease include: epilepsy, congenital and urogenital defects, microcephaly, corpulence, and psychiatric disorders. From analysis of chromosomal breakpoints, as well as gene sequencing in suggestive cases, Kleefstra and colleagues identified EHMT1 as the causative gene. This gene is responsible for producing the protein histone methyltransferase which functions to alter histones. Ultimately, histone methyltransferases are important in deactivating certain genes, needed for proper growth and development. Moreover, a frameshift, missense, or nonsense error in the coding sequence of EHMT1 can result in this condition in an individual.
Lysine demethylase 6B is a protein that in humans is encoded by the KDM6B (JMJD3) gene.
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 light to severe intellectual disability.
Okamoto syndrome (OS), also known as Au–Kline syndrome (AKS), is a very rare autosomal dominant genetic condition characterised by congenital hydronephrosis, low muscle tone, heart defects, intellectual disability and characteristic facial features. Those affected often have neurological and skeletal abnormalities, as well as frequent urinary tract infections. Language and walking are usually delayed. Facial features include prominent, downturned ears, an open, downturned mouth and drooping eyelids (ptosis).
SRD5A3-CDG is a rare, non X-linked congenital disorder of glycosylation (CDG) due to a mutation in the steroid 5 alpha reductase type 3 gene. It is one of over 150 documented types of Congenital disorders of Glycosylation. Like many other CDGs, SRD5A3 is ultra-rare, with around 38 documented cases in the world.
Beck–Fahrner syndrome, also known as BEFAHRS and TET3 deficiency, is a rare genetic disorder caused by mutations of the TET3 gene. The clinical presentation varies among individuals, but typically includes global developmental delay, slow progress in mental and physical activities, autism, decreased muscle tone, epilepsy and dysmorphic features.