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Megalencephaly is a growth development disorder in which the brain is abnormally large. It is characterized by a brain with an average weight that is 2.5 standard deviations above the mean of the general population. Approximately 1 out of 50 children (2%) are said to have the characteristics of megalencephaly in the general population.
Macrocephaly is a condition in which circumference of the human head is abnormally large. It may be pathological or harmless, and can be a familial genetic characteristic. People diagnosed with macrocephaly will receive further medical tests to determine whether the syndrome is accompanied by particular disorders. Those with benign or familial macrocephaly are considered to have megalencephaly.
Metachondromatosis is an autosomal dominant, incompletely penetrant genetic disease affecting the growth of bones, leading to exostoses primarily in the hands and feet as well as enchondromas of long bone metaphyses and iliac crests. This syndrome affects mainly tubular bones, though it can also involve the vertebrae, small joints, and flat bones. The disease is thought to affect exon 4 of the PTPN11 gene. Metachondromatosis is believed to be caused by an 11 base pair deletion resulting in a frameshift and nonsense mutation. The disease was discovered and named in 1971 by Pierre Maroteaux, a French physician, when he observed two families with skeletal radiologic features with exostoses and Ollier disease. The observation of one family with five affected people led to the identification of the disease as autosomal dominant. There have been less than 40 cases of the disease reported to date.
Bannayan–Riley–Ruvalcaba syndrome (BRRS) is a rare overgrowth syndrome and hamartomatous disorder with occurrence of multiple subcutaneous lipomas, macrocephaly and hemangiomas. The disease is inherited in an autosomal dominant manner. The disease belongs to a family of hamartomatous polyposis syndromes, which also includes Peutz–Jeghers syndrome, juvenile polyposis and Cowden syndrome. Mutation of the PTEN gene underlies this syndrome, as well as Cowden syndrome, Proteus syndrome, and Proteus-like syndrome, these four syndromes are referred to as PTEN Hamartoma-Tumor Syndromes.
Cohen syndrome is a very rare autosomal recessive genetic disorder with varied expression, characterised by obesity, intellectual disability, distinct craniofacial abnormalities and potential ocular dysfunction.
Simpson–Golabi–Behmel syndrome (SGBS) is a rare inherited congenital disorder that can cause craniofacial, skeletal, vascular, cardiac, and renal abnormalities. There is a high prevalence of cancer associated in those with SGBS which includes wilms tumors, neuroblastoma, tumors of the adrenal gland, liver, lungs and abdominal organs. The syndrome is inherited in an X-linked recessive manner. Females that possess one copy of the mutation are considered to be carriers of the syndrome but may still express varying degrees of the phenotype, suffering mild to severe malady. Males experience a higher likelihood of fetal death.
Greig cephalopolysyndactyly syndrome is a disorder that affects development of the limbs, head, and face. The features of this syndrome are highly variable, ranging from very mild to severe. People with this condition typically have one or more extra fingers or toes (polydactyly) or an abnormally wide thumb or big toe (hallux).
Weaver syndrome is an extremely rare autosomal dominant genetic disorder associated with rapid growth beginning in the prenatal period and continuing through the toddler and youth years. It is characterized by advanced osseous maturation and distinctive craniofacial, skeletal and neurological abnormalities. It is similar to Sotos syndrome and is classified as an overgrowth syndrome.
Marshall-Smith Syndrome, discovered in 1971, is characterized by unusual accelerated skeletal maturation and symptoms like conspicuous physical characteristics, respiratory difficulties, and mental retardation. Cases described in the literature show a clinical variability regarding related symptoms. For instance, respiratory difficulties are ranging from absent to severe difficulties.
Lujan–Fryns syndrome (LFS) is an X-linked genetic disorder that causes mild to moderate intellectual disability and features described as Marfanoid habitus, referring to a group of physical characteristics similar to those found in Marfan syndrome. These features include a tall, thin stature and long, slender limbs. LFS is also associated with psychopathology and behavioral abnormalities, and it exhibits a number of malformations affecting the brain and heart. The disorder is inherited in an X-linked dominant manner, and is attributed to a missense mutation in the MED12 gene. There is currently no treatment or therapy for the underlying MED12 malfunction, and the exact cause of the disorder remains unclear.
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.
Perlman syndrome (PS), also known as nephroblastomatosis-fetal ascites-macrosomia-Wilms tumor syndrome, is a rare overgrowth syndrome caused by autosomal recessive mutations in the DIS3L2 gene. PS is characterized by macrocephaly, neonatal macrosomia, nephromegaly, renal dysplasia, dysmorphic facial features, and increased risk for Wilms' tumor. The syndrome is associated with high neonatal mortality.
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.
De Barsy syndrome is a rare autosomal recessive genetic disorder. Symptoms include cutis laxa as well as other eye, musculoskeletal, and neurological abnormalities. It is usually progressive, manifesting side effects that can include clouded corneas, cataracts, short stature, dystonia, or progeria.
Genitopatellar syndrome is a rare disorder consisting of congenital flexion contractures of the lower extremities, abnormal or missing patellae, and urogenital anomalies. Additional symptoms include microcephaly, severe psychomotor disability. In 2012, it was shown that mutations in the gene KAT6B cause the syndrome. Genitopatellar syndrome (GTPTS) can be caused by heterozygous mutation in the KAT6B gene on chromosome 10q22. The Say-Barber-Biesecker variant of Ohdo syndrome, which has many overlapping features with GTPTS, can also be caused by heterozygous mutation in the KAT6B gene.
Beare–Stevenson cutis gyrata syndrome is a rare genetic disorder characterized by craniosynostosis and a specific skin abnormality, called cutis gyrata, characterized by a furrowed and wrinkled appearance ; thick, dark, velvety areas of skin are sometimes found on the hands and feet and in the groin.
Fryns-Aftimos syndrome is a rare chromosomal condition and is associated with pachygyria, severe mental retardation, epilepsy and characteristic facial features. This syndrome is a malformation syndrome, characterized by numerous facial dysmorphias not limited to hypertelorism, iris or retinal coloboma, cleft lip, and congenital heart defects. This syndrome has been seen in 30 unrelated people. Characterized by a de novo mutation located on chromosome 7p22, there is typically no family history prior to onset. The severity of the disorder can be determined by the size of the deletion on 7p22, enveloping the ACTB gene and surrounding genes, which is consistent with a contiguous gene deletion syndrome. Confirming a diagnosis of Fryns-Aftimos syndrome typically consists of serial single-gene testing or multigene panel of genes of interest or exome sequencing.
Filippi syndrome, also known as Syndactyly Type I with Microcephaly and Mental Retardation, is a very rare autosomal recessive genetic disease. Only a very limited number of cases have been reported to date. Filippi Syndrome is associated with diverse symptoms of varying severity across affected individuals, for example malformation of digits, craniofacial abnormalities, intellectual disability, and growth retardation. The diagnosis of Filippi Syndrome can be done through clinical observation, radiography, and genetic testing. Filippi Syndrome cannot be cured directly as of 2022, hence the main focus of treatments is on tackling the symptoms observed on affected individuals. It was first reported in 1985.
Otofaciocervical syndrome, also known as Fara Chlupackova syndrome, are a small group of rare developmental disorders of genetic origin which are characterized by facial dysmorphisms, long neck, preauricular and/or branchial pits, cervical muscle hypoplasia, hearing loss, and mild intellectual disabilities. Additional findings include vertebral anomalies and short stature.
Tatton-Brown–Rahman syndrome (TBRS) is a rare overgrowth and intellectual disability syndrome caused by autosomal dominant mutations in the DNMT3A gene. The syndrome was first recognized in 2014 by Katrina Tatton-Brown, Nazneen Rahman, and collaborators.
References
- 1 2 "Malan overgrowth syndrome". Orphanet. December 2020. Retrieved 2024-01-11.
- 1 2 Priolo M, Schanze D, Tatton-Brown K, Mulder PA, Tenorio J, Kooblall K; et al. (2018). "Further delineation of Malan syndrome". Hum Mutat. 39 (9): 1226–1237. doi: 10.1002/humu.23563 . PMC 6175110 . PMID 29897170.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - 1 2 3 4 5 Macchiaiolo M, Panfili FM, Vecchio D, Gonfiantini MV, Cortellessa F, Caciolo C; et al. (2022). "A deep phenotyping experience: up to date in management and diagnosis of Malan syndrome in a single center surveillance report". Orphanet J Rare Dis. 17 (1): 235. doi: 10.1186/s13023-022-02384-9 . PMC 9206304 . PMID 35717370.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ Alfieri P, Macchiaiolo M, Collotta M, Montanaro FAM, Caciolo C, Cumbo F; et al. (2022). "Characterization of Cognitive, Language and Adaptive Profiles of Children and Adolescents with Malan Syndrome". J Clin Med. 11 (14): 4078. doi: 10.3390/jcm11144078 . PMC 9316998 . PMID 35887841.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ Klaassens M, Morrogh D, Rosser EM, Jaffer F, Vreeburg M, Bok LA; et al. (2015). "Malan syndrome: Sotos-like overgrowth with de novo NFIX sequence variants and deletions in six new patients and a review of the literature". Eur J Hum Genet. 23 (5): 610–5. doi: 10.1038/ejhg.2014.162 . PMC 4402637 . PMID 25118028.
{{cite journal}}: CS1 maint: multiple names: authors list (link)