Williams Syndrome(WS) is considered as a neurodevelopmental disorder, caused by a contiguous gene deletion of about 26 genes from the long arm of chromosome 7(Peoples et al., 2000). Since it had been first aware by J.C.P. Williams in 1961(Lenhoff, Wang, Greenberg & Bellugi, 1997), Williams Syndrome has drawn more attention in last 40 years. the incidence rate is approximately 1 in 2000 and diagnosed generally at 6.4 years old (Morris, Demsey, Leonard, Dilts & Blackburn, 1988). People with WS usually show a developmental delay at the early age and are affected all life long. Williams Syndrome is characterised by some abnormalities in physical, behavioural, and cognitive.
Prader-Willi Syndrome causes overeating and never feeling full that leads to type 2 diabetes that can eventually lead to death. 1 in 10,000 to 30,000 people get PWS. People with PWS have chronic overeating and distinctive overeating. It is caused by loss of chromosome 15 or not getting it from the dad’s side, also the lost of the gene called (OCA2). PWS is an autosomal genetic disorder disease caused by the deletion on chromosome 15 or not getting chromosome 15 by the father. Victims with this disorder experience chronic over eating and distinctive facial features(Prader-Willi Syndrome. genetics). A treatment can be therapies.
INTRODUCTION. Idiopathic congenital nystagmus, or idiopathic infantile nystagmus is a disease characterized by the rapid, involuntary eye movement. This movement is typically in the horizontal direction, however, movement in other directions have been observed. One way to get nystagmus is through genetic mutations. Nystagmus caused by genetic mutation is seen at a relatively young age but cannot yet be treated. The disease is not understood well, it is believed that the cause is a developmental defect. The linkage, and inheritance has not been identified, the patterns suggest that multiple genes are involved in the disease and that there are loci on different chromosomes with three of the five loci located on the X chromosome. Mutations have been linked to the FRMD7 gene, a gene that consists of 12 exons, of the FERM family. The function of FRMD7 have yet to be determined however an abundance of the protein in the brain in areas associated with the eye. Mutations within this region consist of missense, deletion, tranversion and nonsense mutations. Over forty-four mutations that lead to ICN have been found in the FRMD7 gene. Learning more about the mutation of FRMD7 in ICN is important because these mutations may prevent elongation of neurite processes during diﬀerentiation preventing axons from responding to stimuli (Watkins et al. 2012).
The chromosomal abnormalities include turner's disease, laron dwarfism, noonan syndrome, sinotina wiley syndrome, russell xifushi, mutation / deletion of the short stature homeobox-containing gene, and skeletal dysplasia.
Opitz syndrome is a disease characterized by a defect along the ventral midline of the human body. Some of these abnormalities include a cleft lip, heart defects, wide-spaced eyes (hypertelerism), laryngeal cleft, agenesis of the corpus callosum, and hypospadias. An important irregularity in patients is the effect disrupted proteins have on the corpus colloseum. The corpus colloseum is a neuronal component that separates the two halves of the brain. This protein is imperative because it controls MID-1 or the midline. The MID-1 protein also forms homodimers, which associate with microtubules in the cytoplasm, especially during fetal development. Therefore, MID-1 is involved in formation of multiprotein structures, acting as anchor points to
Dandy-Walker Syndrome or Dandy-Walker Malformation is a congenital malformation of the cerebellum and the fluid filled space surrounding it. The malformation can include an enlargement of the fourth ventricle, a partial or complete absence of the space between the two hemispheres of the cerebellum (called the vermis), and a cyst formation near the lowest part of the skull (National Institute of Neurological Disorders and Stroke [NINDS], 2016). Dandy-Walker Syndrome is found in approximately 1 of 25,000 to 35,000 live births and is more prevalent in females than males (NORD-National Organization for Rare Disorders, 2008). Although an exact case is not known, the syndrome may be a result of defects in the embryonic development of the cerebellum. Research has found that in some cases patients have chromosomal abnormalities. Dandy-Walker may also be caused by genetic abnormalities or environmental factors, teratogens (NORD-National Organization for Rare Disorders, 2008). Maternal diabetes and infections passed through the mother to the fetus may also result in a child born with Dandy-Walker Syndrome (Childrens National Health System, 2016).
Hydrocephaly-MASA Spectrum is the most common XLID syndrome with a structural malformation of the central nervous system. Isolation of mutations in L1CAM has allowed inclusion of four entities that were previously thought to be separate entities in the spectrum; these include X-linked hydrocephaly, MASA syndrome, XLID-clasp thumb and complicated spastic paraplegia (Stevenson RE., 2013). Hypotonia is usually present initially and replaced by spasticity in the late childhood. Interestingly, the degree of intellectual development of these individuals appears to be correlated with the severity of hydrocephaly.
The prevalence of hearing loss has doubled over the past 30 years in the United States and continues to steadily incline as time goes on. Hearing loss itself encompasses a wide variety of disorders, effects many diverse populations, and is caused due to a multitude of different sources (“The Prevalence”). Its onset is also extremely variant and could happen either congenitally or at any point later on in a person’s life. One of these such congenital disorders is Waardenburg syndrome. Waardenburg syndrome is a genetic disorder characteristized by four different types of specific disorders that are further differentiated by their physical attributes and genetic causes. It’s estimated that about 1 in 40000 people are diagnosed with this disorder
Neurodevelopmental disorders are characterized by impairments of the growth and development of the central nervous system as they occur by origin, or during infancy and childhood, inhibiting functions that affect emotion, learning, self-control, motor skills, and memory. Specific disorders within this spectrum include but are not limited to, fetal alcohol syndrome, autism, Tourette syndrome, fragile-X syndrome, Down syndrome, ADHD, Mendelsohn’s syndrome, and schizophrenia. Neurodevelopmental disorders stem from many causes, ranging from chromosomal deficiency, genetic and metabolic diseases, immune disorders, infectious diseases, physical trauma, and nutritional, toxic, and environmental factors (Bale, et.al., 2010).
With an abnormal number of repeats the trinucleotide sequence becomes more unstable and disease symptoms grow to be more visible. Myotonic dystrophy II (DM2) is a mutation of cellular nucleic acid binding protein (CNBP), or zinc finger protein 9. The functions of both proteins, CNBP and DMPK are uncertain, however they can be found in multiple organs and tissues in the body, including the brain, cardiac, and skeletal muscles (Ueada, Ohno & Kobayashi, 2000). Myotonic dystrophy is located on chromosome 19q13.3 and is a result of an abnormal repeat of the DNA sequence. According to Mckusick & Hartz (1986) People with DM2 can have from 75 to more than 11,000 CCTG repeats. Both DM1 and DM2 are autosomal dominant inheritable disease, which can be passed along to offspring if the parent is affected, at a 50% probability. Myotonic dystrophy is unique from most provided that “disease-causing alleles may expand in length during gametogenesis, resulting in the transmission of longer trinucleotide repeat alleles that may be associated with earlier onset and more severe disease than that observed in the parent” (Bird et al., 1999).
The genetics of neurodevelopmental disorders (NDD) rarely display a Mendelian mode of inheritance, and can result from a single rare gene mutation, more common variations in single nucleotide polymorphisms, or often a combination of these two factors in conjunction with environmental influences . In contrast, epigenetic mechanisms are heritable changes in gene expression which do not change the DNA sequence . Epigenetic changes to the genome may predispose the development of NDD when combined with the aforementioned genetic risk factors .
To further determine the condition and identity of the specimen, analysis of cranial shape and size was conducted in 2006. When LB1 was compared to specimens that exhibited known microcephaly, it was determined that LB1 has a much shorter cranium relative to the distance between the ears, and that LB1 is therefore inconsistent with ranges of microcephaly. Along with this vector, LB1 also contains a much smaller cranial volume when compared to specimens of microcephalic and pygmoid variance. LB1 is far enough outside the range of variation for such conditions, making it reasonable to conclude that LB1 is not representative of a case of either condition. (Argue, et al.)
Seckel Syndrome reported by Mann and Russel in 1959, this condition was extensively studied by Seckel in 1960. More precise criteria for diagnosis have been recently been set forth.