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Colpocephaly is a cephalic disorder involving the disproportionate enlargement of the occipital horns of the lateral ventricles and is usually diagnosed early after birth due to seizures. It is a nonspecific finding and is associated with multiple neurological syndromes, including agenesis of the corpus callosum, Chiari malformation, lissencephaly, and microcephaly. Although the exact cause of colpocephaly is not known yet, it is commonly believed to occur as a result of neuronal migration disorders during early brain development, intrauterine disturbances, perinatal injuries, and other central nervous system disorders. Individuals with colpocephaly have various degrees of motor disabilities, visual defects, spasticity, and moderate to severe intellectual disability. No specific treatment for colpocephaly exists, but patients may undergo certain treatments to improve their motor function or intellectual disability.
Microcephaly is a medical condition involving a smaller-than-normal head. Microcephaly may be present at birth or it may develop in the first few years of life. Brain development is often affected; people with this disorder often have an intellectual disability, poor motor function, poor speech, abnormal facial features, seizures and dwarfism.
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.
Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13. The extra genetic material disrupts normal development, causing multiple and complex organ defects.
Trisomy 18, also known as Edwards syndrome, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18. Many parts of the body are affected. Babies are often born small and have heart defects. Other features include a small head, small jaw, clenched fists with overlapping fingers, and severe intellectual disability.
Aicardi syndrome is a rare genetic malformation syndrome characterized by the partial or complete absence of a key structure in the brain called the corpus callosum, the presence of retinal lacunes, and epileptic seizures in the form of infantile spasms. Other malformations of the brain and skeleton may also occur. The syndrome includes intellectual disability that is usually severe or moderate. So far, the syndrome has only been diagnosed in girls and in boys with two X chromosomes.
Miller–Dieker syndrome, also called Miller–Dieker lissencephaly syndrome (MDLS) or chromosome 17p13.3 deletion syndrome, is a micro deletion syndrome characterized by congenital malformations. Congenital malformations are physical defects detectable in an infant at birth which can involve many different parts of the body, including the brain, heart, lungs, liver, bones, or intestinal tract. MDS is a contiguous gene syndrome – a disorder due to the deletion of multiple gene loci adjacent to one another. The disorder arises from the deletion of part of the small arm of chromosome 17p, leading to partial monosomy. There may be unbalanced translocations, or the presence of a ring chromosome 17.
Polymicrogyria (PMG) is a condition that affects the development of the human brain by multiple small gyri (microgyri) creating excessive folding of the brain leading to an abnormally thick cortex. This abnormality can affect either one region of the brain or multiple regions.
Cri du chat syndrome is a rare genetic disorder due to a partial chromosome deletion on chromosome 5. Its name is a French term referring to the characteristic cat-like cry of affected children. It was first described by Jérôme Lejeune in 1963. The condition affects an estimated 1 in 50,000 live births across all ethnicities and is more common in females by a 4:3 ratio.
Trisomy 8 causes Warkany syndrome 2, a human chromosomal disorder caused by having three copies (trisomy) of chromosome 8. It can appear with or without mosaicism.
Monosomy 9p is a rare chromosomal disorder in which some DNA is missing or has been deleted on the short arm region, "p", of one copy of chromosome 9 (9p22.2-p23). This deletion either happens de novo or as a result of a parent having the chromosome abnormality. This rare chromosomal abnormality is often diagnosed after birth when developmental delay, irregular facial features, structural irregularities within the heart, and genital defects are observed. Treatments for this syndrome usually focus on fixing the malformations that are commonly associated with it. The cause of the syndrome was first discovered by Dr. Omar Alfi in 1973, when an analysis of the chromosomes of three infants with similar clinical abnormalities revealed that they all had a partial deletion of the short arm of Chromosome 9. Symptoms include micro genitalia, intellectual disability with microcephaly and dysmorphic features.
The Pallister–Killian syndrome (PKS), also termed tetrasomy 12p mosaicism or the Pallister mosaic aneuploidy syndrome, is an extremely rare and severe genetic disorder. PKS is due to the presence of an extra and abnormal chromosome termed a small supernumerary marker chromosome (sSMC). sSMCs contain copies of genetic material from parts of virtually any other chromosome and, depending on the genetic material they carry, can cause various genetic disorders and neoplasms. The sSMC in PKS consists of multiple copies of the short arm of chromosome 12. Consequently, the multiple copies of the genetic material in the sSMC plus the two copies of this genetic material in the two normal chromosome 12's are overexpressed and thereby cause the syndrome. Due to a form of genetic mosaicism, however, individuals with PKS differ in the tissue distributions of their sSMC and therefore show different syndrome-related birth defects and disease severities. For example, individuals with the sSMC in their heart tissue are likely to have cardiac structural abnormalities while those without this sSMC localization have a structurally normal heart.
1p36 deletion syndrome is a congenital genetic disorder characterized by moderate to severe intellectual disability, delayed growth, hypotonia, seizures, limited speech ability, malformations, hearing and vision impairment, and distinct facial features. The symptoms may vary, depending on the exact location of the chromosomal deletion.
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.
Fryns syndrome is an autosomal recessive multiple congenital anomaly syndrome that is usually lethal in the neonatal period. Fryns (1987) reviewed the syndrome.
Lenz microphthalmia syndrome is a very rare inherited disorder characterized by abnormal smallness of one or both eyes (microphthalmos) sometimes with droopy eyelids (blepharoptosis), resulting in visual impairment or blindness. Eye problems may include coloboma, microcornea, and glaucoma. Some affected infants may have complete absence of the eyes (anophthalmia). Most affected infants have developmental delay and intellectual disability, ranging from mild to severe. Other physical abnormalities associated with this disorder can include an unusually small head (microcephaly), and malformations of the teeth, ears, fingers or toes, skeleton, and genitourinary system. The range and severity of findings vary from case to case. Formal diagnosis criteria do not exist.
13q deletion syndrome is a rare genetic disease caused by the deletion of some or all of the large arm of human chromosome 13. Depending upon the size and location of the deletion on chromosome 13, the physical and mental manifestations will vary. It has the potential to cause intellectual disability and congenital malformations that affect a variety of organ systems. Because of the rarity of the disease in addition to the variations in the disease, the specific genes that cause this disease are unknown. This disease is also known as:
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.
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.
Strømme syndrome is a very rare autosomal recessive genetic condition characterised by intestinal atresia, eye abnormalities and microcephaly. The intestinal atresia is of the "apple-peel" type, in which the remaining intestine is twisted around its main artery. The front third of the eye is typically underdeveloped, and there is usually moderate developmental delay. Less common features include an atrial septal defect, increased muscle tone or skeletal abnormalities. Physical features may include short stature, large, low-set ears, a small jaw, a large mouth, epicanthic folds, or fine, sparse hair.
References
- ↑ Ginsburg, David; Gelehrter, Thomas D.; Collins, Francis S. (1998). Principles of medical genetics . Baltimore: Williams & Wilkins. pp. 169. ISBN 0-683-03445-6.
- ↑ McConnell V, Derham R, McManus D, Morrison PJ (July 2004). "Mosaic monosomy 14: clinical features and recognizable facies". Clin. Dysmorphol. 13 (3): 155–60. doi:10.1097/01.mcd.0000126137.29572.59. PMID 15194951. S2CID 22523296.
- ↑ Cantú ES, Thomas IT, Frias JL (September 1989). "Unusual cytogenetic mosaicism involving chromosome 14 abnormalities in a child with an MR/MCA syndrome and abnormal pigmentation". Clin. Genet. 36 (3): 189–95. doi:10.1111/j.1399-0004.1989.tb03187.x. PMID 2676269. S2CID 40718643.
