MedGen

Medulloblastoma is the most common brain tumor in children. It accounts for 16% of all pediatric brain tumors, and 40% of all cerebellar tumors in childhood are medulloblastoma. Medulloblastoma occurs bimodally, with peak incidences between 3 and 4 years and 8 and 9 years of age. Approximately 10 to 15% of medulloblastomas are diagnosed in infancy. Medulloblastoma accounts for less than 1% of central nervous system (CNS) tumors in adults, with highest incidence in adults 20 to 34 years of age. In 1 to 2% of patients, medulloblastoma is associated with Gorlin syndrome (109400), a nevoid basal carcinoma syndrome. Medulloblastoma also occurs in up to 40% of patients with Turcot syndrome (see 276300). Medulloblastoma is thought to arise from neural stem cell precursors in the granular cell layer of the cerebellum. Standard treatment includes surgery, chemotherapy, and, depending on the age of the patient, radiation therapy (Crawford et al., 2007). Millard and De Braganca (2016) reviewed the histopathologic variants and molecular subgroups of medulloblastoma. Pretreatment prognosis of medulloblastoma has been refined by histopathologic subclassification into the following variants: large-cell medulloblastoma, anaplastic medulloblastoma, desmoplastic/nodular medulloblastoma, and medulloblastoma with extensive nodularity (MBEN). The latter 2 groups have been shown to have a significantly superior prognosis as compared to the large cell and anaplastic groups in young children. At the molecular level, medulloblastomas have been categorized into the following subgroups: wingless (WNT), sonic hedgehog (SHH), group 3, and group 4. Each subgroup is characterized by a unique set of genetics and gene expression as well as demographic and clinical features. [from OMIM]

The creatine deficiency disorders (CDDs), inborn errors of creatine metabolism and transport, comprise three disorders: the creatine biosynthesis disorders guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency; and creatine transporter (CRTR) deficiency. Developmental delay and cognitive dysfunction or intellectual disability and speech-language disorder are common to all three CDDs. Onset of clinical manifestations of GAMT deficiency (reported in ~130 individuals) is between ages three months and two years; in addition to developmental delays, the majority of individuals have epilepsy and develop a behavior disorder (e.g., hyperactivity, autism, or self-injurious behavior), and about 30% have movement disorder. AGAT deficiency has been reported in 16 individuals; none have had epilepsy or movement disorders. Clinical findings of CRTR deficiency in affected males (reported in ~130 individuals) in addition to developmental delays include epilepsy (variable seizure types and may be intractable) and behavior disorders (e.g., attention deficit and/or hyperactivity, autistic features, impulsivity, social anxiety), hypotonia, and (less commonly) a movement disorder. Poor weight gain with constipation and prolonged QTc on EKG have been reported. While mild-to-moderate intellectual disability is commonly observed up to age four years, the majority of adult males with CRTR deficiency have been reported to have severe intellectual disability. Females heterozygous for CRTR deficiency are typically either asymptomatic or have mild intellectual disability, although a more severe phenotype resembling the male phenotype has been reported. [from GeneReviews]

The creatine deficiency disorders (CDDs), inborn errors of creatine metabolism and transport, comprise three disorders: the creatine biosynthesis disorders guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency; and creatine transporter (CRTR) deficiency. Developmental delay and cognitive dysfunction or intellectual disability and speech-language disorder are common to all three CDDs. Onset of clinical manifestations of GAMT deficiency (reported in ~130 individuals) is between ages three months and two years; in addition to developmental delays, the majority of individuals have epilepsy and develop a behavior disorder (e.g., hyperactivity, autism, or self-injurious behavior), and about 30% have movement disorder. AGAT deficiency has been reported in 16 individuals; none have had epilepsy or movement disorders. Clinical findings of CRTR deficiency in affected males (reported in ~130 individuals) in addition to developmental delays include epilepsy (variable seizure types and may be intractable) and behavior disorders (e.g., attention deficit and/or hyperactivity, autistic features, impulsivity, social anxiety), hypotonia, and (less commonly) a movement disorder. Poor weight gain with constipation and prolonged QTc on EKG have been reported. While mild-to-moderate intellectual disability is commonly observed up to age four years, the majority of adult males with CRTR deficiency have been reported to have severe intellectual disability. Females heterozygous for CRTR deficiency are typically either asymptomatic or have mild intellectual disability, although a more severe phenotype resembling the male phenotype has been reported. [from GeneReviews]

Coffin-Siris syndrome is a congenital malformation syndrome characterized by developmental delay, intellectual disability, coarse facial features, feeding difficulties, and hypoplastic or absent fifth fingernails and fifth distal phalanges. Other more variable features may also occur. Patients with SMARCA4 mutations may have less coarse craniofacial appearances and fewer behavioral abnormalities than Coffin-Siris patients with mutations in other genes (summary by Kosho et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of Coffin-Siris syndrome, see CSS1 (135900). [from OMIM]

The creatine deficiency disorders (CDDs), inborn errors of creatine metabolism and transport, comprise three disorders: the creatine biosynthesis disorders guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency; and creatine transporter (CRTR) deficiency. Developmental delay and cognitive dysfunction or intellectual disability and speech-language disorder are common to all three CDDs. Onset of clinical manifestations of GAMT deficiency (reported in ~130 individuals) is between ages three months and two years; in addition to developmental delays, the majority of individuals have epilepsy and develop a behavior disorder (e.g., hyperactivity, autism, or self-injurious behavior), and about 30% have movement disorder. AGAT deficiency has been reported in 16 individuals; none have had epilepsy or movement disorders. Clinical findings of CRTR deficiency in affected males (reported in ~130 individuals) in addition to developmental delays include epilepsy (variable seizure types and may be intractable) and behavior disorders (e.g., attention deficit and/or hyperactivity, autistic features, impulsivity, social anxiety), hypotonia, and (less commonly) a movement disorder. Poor weight gain with constipation and prolonged QTc on EKG have been reported. While mild-to-moderate intellectual disability is commonly observed up to age four years, the majority of adult males with CRTR deficiency have been reported to have severe intellectual disability. Females heterozygous for CRTR deficiency are typically either asymptomatic or have mild intellectual disability, although a more severe phenotype resembling the male phenotype has been reported. [from GeneReviews]

Congenital tufting enteropathy (CTE) is a rare inherited intractable diarrhea of infancy characterized by villous atrophy and absence of inflammation, with intestinal epithelial cell dysplasia manifesting as focal epithelial tufts in the duodenum and jejunum. CTE presents in the first few months of life with chronic watery diarrhea and failure to thrive, and most affected individuals require parenteral nutrition for normal growth and development (summary by Sivagnanam et al., 2008). Semiquantitative assessment of the epithelial surface in CTE patients revealed that 80 to 90% contained tufts, compared to only 16% in patients with celiac disease and less than 10% in normal jejunum (Reifen et al., 1994). For a discussion of genetic heterogeneity of diarrhea, see DIAR1 (214700). [from OMIM]

Alpha-thalassemia (a-thalassemia) has two clinically significant forms: hemoglobin Bart hydrops fetalis (Hb Bart) syndrome (caused by deletion/inactivation of all four a-globin genes; --/--), and hemoglobin H (HbH) disease (most frequently caused by deletion/inactivation of three a-globin genes; --/-a). Hb Bart syndrome, the more severe form, is characterized by prenatal onset of generalized edema and pleural and pericardial effusions as a result of congestive heart failure induced by severe anemia. Extramedullary erythropoiesis, marked hepatosplenomegaly, and a massive placenta are common. Death usually occurs in the neonatal period. HbH disease has a broad phenotypic spectrum: although clinical features usually develop in the first years of life, HbH disease may not present until adulthood or may be diagnosed only during routine hematologic analysis in an asymptomatic individual. The majority of individuals have enlargement of the spleen (and less commonly of the liver), mild jaundice, and sometimes thalassemia-like bone changes. Individuals with HbH disease may develop gallstones and experience acute episodes of hemolysis in response to infections or exposure to oxidant drugs. [from GeneReviews]

Tafenoquine is an antimalarial agent that was approved by the FDA in 2018 for preventing malaria (brand name Arakoda, 100 mg tablets), and for the radical cure of malaria (brand name Krintafel, 150 mg tablets) caused by Plasmodium vivax (P. vivax). Malaria is caused by the Plasmodium parasite, which infects mosquitos and is spread to humans when an infected mosquito bites a person. In 2018 the World Health Organization (WHO) estimated 228 million cases of malaria occurred worldwide. There are several clinical patterns of malaria that are caused by different species of the parasite. In P. vivax malaria, the parasite can lie dormant in the liver as hypnozoites, until it emerges weeks or months later, to cause a relapse of malaria. In combination with an antimalarial active against the blood stage parasites, tafenoquine provides a radical cure of P. vivax by targeting its dormant liver stage, thus preventing malaria relapse. Tafenoquine is the second drug of its kind (with hypnozoiticidal activity) to be approved by the FDA. The first was primaquine, approved in 1952. Because of its longer half-life, tafenoquine can be dosed less frequently than primaquine, which may improve compliance. For example, when used for the radical cure of P. vivax malaria, tafenoquine is taken as a single 300 mg dose (in uncomplicated cases, in persons aged 16 years and older). In contrast, primaquine radical cure is recommended to be given daily over 14 days, or higher doses over 7 days. Tafenoquine, like primaquine, should not be used in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. In the case of tafenoquine, an individual with <70% of normal G6PD activity is considered deficient and should not take the drug. Worldwide, approximately 400 million people have a deficiency of the G6PD enzyme, but most are asymptomatic and do not know they are at risk. A lack of G6PD in red blood cells makes the cells susceptible to damage by oxidative stress. Usually, only low levels of oxidative stress occur naturally, and so the condition is undetected. However, certain drugs, which include tafenoquine and primaquine, are oxidizing agents. In people with G6PD deficiency, these drugs cause irreparable oxidative damage to the red blood cells, which are then rapidly destroyed (hemolysis). This can lead to a potentially life-threatening deficiency of mature red blood cells (hemolytic anemia). The FDA-approved drug label for tafenoquine states that testing for G6PD must be performed before starting tafenoquine therapy, and that all individuals should be monitored for signs of hemolysis. In addition, because of the risk of tafenoquine causing fetal harm in a woman pregnant with a fetus with G6PD deficiency, pregnancy testing is highly recommended in women of reproductive age. Consequently, tafenoquine therapy is contraindicated in adults when the G6PD status is either unknown, intermediate or deficient, namely, enzyme activity lower than 70%, in pregnancy, and in breastfeeding mothers when the infant’s G6PD status is either unknown or deficient. To date, no safety studies have been reported in children. [from Medical Genetics Summaries]

Tyrosinase-positive oculocutaneous albinism (OCA, type II; OCA2) is an autosomal recessive disorder in which the biosynthesis of melanin pigment is reduced in skin, hair, and eyes. Although affected infants may appear at birth to have OCA type I, or complete absence of melanin pigment, most patients with OCA type II acquire small amounts of pigment with age. Individuals with OCA type II have the characteristic visual anomalies associated with albinism, including decreased acuity and nystagmus, which are usually less severe than in OCA type I (Lee et al., 1994; King et al., 2001). OCA type II has a highly variable phenotype. The hair of affected individuals may turn darker with age, and pigmented nevi or freckles may be seen. African and African American individuals may have yellow hair and blue-gray or hazel irides. One phenotypic variant, 'brown OCA,' has been described in African and African American populations and is characterized by light brown hair and skin color and gray to tan irides. The hair and irides may turn darker with time and the skin may tan with sun exposure; the ocular features of albinism are present in all variants (King et al., 2001). In addition, previous reports of so-called 'autosomal recessive ocular albinism,' (see, e.g., Witkop et al., 1978 and O'Donnell et al., 1978) with little or no obvious skin involvement, are now considered most likely to be part of the phenotypic spectrum of OCA1 or OCA2 (Lee et al., 1994; King et al., 2001). [from OMIM]

A measured foot length that is more than 2 SD below the mean for a newborn of 27 - 41 weeks gestation, or foot that is less than the 3rd centile for individuals from birth to 16 years of age (objective). Alternatively, a foot that appears disproportionately short (subjective). [from HPO]

Carisoprodol is a centrally acting muscle relaxant used to relieve acute back pain. Due to the risk of dependence and abuse, carisoprodol should only be used for treatment periods of up to two or three weeks. Carisoprodolol is a Schedule IV controlled substance and carisoprodol overdose can lead to CNS respiratory depression, seizures, and death. Carisoprodol is metabolized by CYP2C19 to meprobamate, a sedative used to treat anxiety disorders. In individuals who have little or no CYP2C19 activity (“CYP2C19 poor metabolizers”), standard doses of carisoprodol can lead to a 4-fold increase in exposure to carisoprodol and a concomitant 50% reduced exposure to meprobamate compared to normal metabolizers. Approximately 3-5% of Caucasians and Africans, and 15-20% of Asians, are CYP2C19 poor metabolizers. The FDA-approved drug label for carisoprodol states that caution should be used when administering carisoprodol to patients with reduced CYP2C19 activity and when co-administering drugs that inhibit or induce CYP2C19. There are no data on the use of carisoprodol in pregnancy, and the efficacy, safety, and pharmacokinetics of carisoprodol have not been established in pediatric patients (less than 16 years of age). [from Medical Genetics Summaries]

Autism, the prototypic pervasive developmental disorder (PDD), is usually apparent by 3 years of age. It is characterized by a triad of limited or absent verbal communication, a lack of reciprocal social interaction or responsiveness, and restricted, stereotypic, and ritualized patterns of interests and behavior (Bailey et al., 1996; Risch et al., 1999). 'Autism spectrum disorder,' sometimes referred to as ASD, is a broader phenotype encompassing the less severe disorders Asperger syndrome (see ASPG1; 608638) and pervasive developmental disorder, not otherwise specified (PDD-NOS). 'Broad autism phenotype' includes individuals with some symptoms of autism, but who do not meet the full criteria for autism or other disorders. Impaired intellectual development (IDD) coexists in approximately two-thirds of individuals with ASD, except for Asperger syndrome, in which IDD is conspicuously absent (Jones et al., 2008). Genetic studies in autism often include family members with these less stringent diagnoses (Schellenberg et al., 2006). For a discussion of heterogeneity of autism, see 209850. [from OMIM]

Aarskog-Scott syndrome is a genetic disorder that affects the development of many parts of the body, most commonly the head and face, the hands and feet, and the genitals and urinary system (genitourinary tract). This condition mainly affects males, although females may have mild features of the syndrome.

People with Aarskog-Scott syndrome often have distinctive facial features, such as widely spaced eyes (hypertelorism), a small nose, a long area between the nose and mouth (philtrum), and a widow's peak hairline. They frequently have mild to moderate short stature during childhood, but their growth usually catches up with that of their peers during puberty. Hand abnormalities are common in this syndrome and include short fingers (brachydactyly), curved pinky fingers (fifth finger clinodactyly), webbing of the skin between some fingers (cutaneous syndactyly), and a single crease across the palm. Affected individuals can also have wide, flat feet with broad, rounded toes. Other abnormalities in people with Aarskog-Scott syndrome include heart defects and a split in the upper lip (cleft lip) with or without an opening in the roof of the mouth (cleft palate).

Most males with Aarskog-Scott syndrome have a shawl scrotum, in which the scrotum surrounds the penis instead of hanging below. Less often, they have undescended testes (cryptorchidism) or a soft out-pouching around the belly-button (umbilical hernia) or in the lower abdomen (inguinal hernia).

The intellectual development of people with Aarskog-Scott syndrome varies widely. Most individuals with Aarskog-Scott syndrome have normal intelligence; however, some may have mild learning and behavior problems, and in rare cases, severe intellectual disability has been reported. [from MedlinePlus Genetics]

The creatine deficiency disorders (CDDs), inborn errors of creatine metabolism and transport, comprise three disorders: the creatine biosynthesis disorders guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency; and creatine transporter (CRTR) deficiency. Developmental delay and cognitive dysfunction or intellectual disability and speech-language disorder are common to all three CDDs. Onset of clinical manifestations of GAMT deficiency (reported in ~130 individuals) is between ages three months and two years; in addition to developmental delays, the majority of individuals have epilepsy and develop a behavior disorder (e.g., hyperactivity, autism, or self-injurious behavior), and about 30% have movement disorder. AGAT deficiency has been reported in 16 individuals; none have had epilepsy or movement disorders. Clinical findings of CRTR deficiency in affected males (reported in ~130 individuals) in addition to developmental delays include epilepsy (variable seizure types and may be intractable) and behavior disorders (e.g., attention deficit and/or hyperactivity, autistic features, impulsivity, social anxiety), hypotonia, and (less commonly) a movement disorder. Poor weight gain with constipation and prolonged QTc on EKG have been reported. While mild-to-moderate intellectual disability is commonly observed up to age four years, the majority of adult males with CRTR deficiency have been reported to have severe intellectual disability. Females heterozygous for CRTR deficiency are typically either asymptomatic or have mild intellectual disability, although a more severe phenotype resembling the male phenotype has been reported. [from GeneReviews]

PRRT2-associated paroxysmal movement disorders (PRRT2-PxMD) include paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), paroxysmal kinesigenic dyskinesia with infantile convulsions (PKD/IC), and hemiplegic migraine (HM). In addition, PRRT2 pathogenic variants have been identified in other childhood-onset movement disorders and different types of seizures, suggesting that the understanding of the spectrum of PRRT2-PxMD is still evolving. The paroxysmal attacks in PKD are characterized by dystonia, choreoathetosis, and less commonly ballismus. The seizures of BFIE are usually focal with or without generalization. Thirty percent of PRRT2-associated PKD is associated with BFIE and is referred to as PKD/IC. [from GeneReviews]

PRRT2-associated paroxysmal movement disorders (PRRT2-PxMD) include paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), paroxysmal kinesigenic dyskinesia with infantile convulsions (PKD/IC), and hemiplegic migraine (HM). In addition, PRRT2 pathogenic variants have been identified in other childhood-onset movement disorders and different types of seizures, suggesting that the understanding of the spectrum of PRRT2-PxMD is still evolving. The paroxysmal attacks in PKD are characterized by dystonia, choreoathetosis, and less commonly ballismus. The seizures of BFIE are usually focal with or without generalization. Thirty percent of PRRT2-associated PKD is associated with BFIE and is referred to as PKD/IC. [from GeneReviews]

People with SLE have episodes in which the condition gets worse (exacerbations) and other times when it gets better (remissions). Overall, SLE gradually gets worse over time, and damage to the major organs of the body can be life-threatening.

About a third of people with SLE develop kidney disease (nephritis). Heart problems may also occur in SLE, including inflammation of the sac-like membrane around the heart (pericarditis) and abnormalities of the heart valves, which control blood flow in the heart. Heart disease caused by fatty buildup in the blood vessels (atherosclerosis), which is very common in the general population, is even more common in people with SLE. The inflammation characteristic of SLE can also damage the nervous system, and may result in abnormal sensation and weakness in the limbs (peripheral neuropathy); seizures; stroke; and difficulty processing, learning, and remembering information (cognitive impairment). Anxiety and depression are also common in SLE.

SLE may first appear as extreme tiredness (fatigue), a vague feeling of discomfort or illness (malaise), fever, loss of appetite, and weight loss. Most affected individuals also have joint pain, typically affecting the same joints on both sides of the body, and muscle pain and weakness. Skin problems are common in SLE. A characteristic feature is a flat red rash across the cheeks and bridge of the nose, called a "butterfly rash" because of its shape. The rash, which generally does not hurt or itch, often appears or becomes more pronounced when exposed to sunlight. Other skin problems that may occur in SLE include calcium deposits under the skin (calcinosis), damaged blood vessels (vasculitis) in the skin, and tiny red spots called petechiae. Petechiae are caused by a shortage of cells involved in clotting (platelets), which leads to bleeding under the skin. Affected individuals may also have hair loss (alopecia) and open sores (ulcerations) in the moist lining (mucosae) of the mouth, nose, or, less commonly, the genitals.

Systemic lupus erythematosus (SLE) is a chronic disease that causes inflammation in connective tissues, such as cartilage and the lining of blood vessels, which provide strength and flexibility to structures throughout the body. The signs and symptoms of SLE vary among affected individuals, and can involve many organs and systems, including the skin, joints, kidneys, lungs, central nervous system, and blood-forming (hematopoietic) system. SLE is one of a large group of conditions called autoimmune disorders that occur when the immune system attacks the body's own tissues and organs. [from MedlinePlus Genetics]

Spondylometaphyseal dysplasia with cone-rod dystrophy (SMDCRD) is characterized by postnatal growth deficiency resulting in profound short stature, rhizomelia with bowing of the lower extremities, platyspondyly with anterior vertebral protrusions, progressive metaphyseal irregularity and cupping with shortened tubular bones, and early-onset progressive visual impairment associated with a pigmentary maculopathy and electroretinographic evidence of cone-rod dysfunction (summary by Hoover-Fong et al., 2014). Yamamoto et al. (2014) reviewed 16 reported cases of SMDCRD, noting that all affected individuals presented uniform skeletal findings, with rhizomelia and bowed lower limbs observed in the first year of life, whereas retinal dystrophy had a more variable age of onset. There was severe disproportionate short stature, with a final height of less than 100 cm; scoliosis was usually mild. Visual loss was progressive, with stabilization in adolescence. [from OMIM]

Congenital alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is characterized histologically by failure of formation and ingrowth of alveolar capillaries that then do not make contact with alveolar epithelium, medial muscular thickening of small pulmonary arterioles with muscularization of the intraacinar arterioles, thickened alveolar walls, and anomalously situated pulmonary veins running alongside pulmonary arterioles and sharing the same adventitial sheath. Less common features include a reduced number of alveoli and a patchy distribution of the histopathologic changes. The disorder is associated with persistent pulmonary hypertension of the neonate and shows varying degrees of lability and severity (Boggs et al., 1994). Affected infants present with respiratory distress resulting from pulmonary hypertension in the early postnatal period, and the disease is uniformly fatal within the newborn period (Vassal et al., 1998). Additional features of ACDMPV include multiple congenital anomalies affecting the cardiovascular, gastrointestinal, genitourinary, and musculoskeletal systems, as well as disruption of the normal right-left asymmetry of intrathoracic or intraabdominal organs (Sen et al., 2004). [from OMIM]

PRRT2-associated paroxysmal movement disorders (PRRT2-PxMD) include paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), paroxysmal kinesigenic dyskinesia with infantile convulsions (PKD/IC), and hemiplegic migraine (HM). In addition, PRRT2 pathogenic variants have been identified in other childhood-onset movement disorders and different types of seizures, suggesting that the understanding of the spectrum of PRRT2-PxMD is still evolving. The paroxysmal attacks in PKD are characterized by dystonia, choreoathetosis, and less commonly ballismus. The seizures of BFIE are usually focal with or without generalization. Thirty percent of PRRT2-associated PKD is associated with BFIE and is referred to as PKD/IC. [from GeneReviews]