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.
Chromosome 15 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 15 spans about 99.7 million base pairs and represents between 3% and 3.5% of the total DNA in cells. Chromosome 15 is an acrocentric chromosome, with a very small short arm, which contains few protein coding genes among its 19 million base pairs. It has a larger long arm that is gene rich, spanning about 83 million base pairs.
Chromosome 16 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 16 spans about 96 million base pairs and represents just under 3% of the total DNA in cells.
22q13 deletion syndrome, also 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.
The Olduvai domain, known until 2018 as DUF1220 and the NBPF repeat, is a protein domain that shows a striking human lineage-specific (HLS) increase in copy number and appears to be involved in human brain evolution. The protein domain has also been linked to several neurogenetic disorders such as schizophrenia and increased severity of autism. In 2018, it was named by its discoverers after Olduvai Gorge in Tanzania, one of the most important archaeological sites for early humans, to reflect data indicating its role in human brain size and evolution.
Isodicentric 15, also called marker chromosome 15 syndrome, idic(15), partial tetrasomy 15q, or inverted duplication 15, is a chromosome abnormality in which a child is born with extra genetic material from chromosome 15. People with idic(15) are typically born with 47 chromosomes in their body cells, instead of the normal 46. The extra chromosome, which is classified as a small supernumerary marker chromosome, is made up of a piece of chromosome 15 that has been duplicated end-to-end like a mirror image. It is the presence of this extra genetic material that is thought to account for the symptoms seen in some people with idic(15). Individuals with idic(15) have a total of four copies of this chromosome 15 region instead of the usual two copies. The term isodicentric refers to a duplication and inversion of a centromere-containing chromosomal segment.
Intermembrane lipid transfer protein VPS13B, also known as vacuolar protein sorting-associated 13B, and Cohen syndrome protein 1 is a protein that in humans is encoded by the VPS13B gene. It is a giant protein associated with the Golgi apparatus that is believed to be involved in post-Golgi apparatus sorting and trafficking. Mutations in the human VPS13B gene cause Cohen syndrome.
B-cell CLL/lymphoma 9 protein is a protein that in humans is encoded by the BCL9 gene.
The Center for Applied Genomics is a research center at the Children's Hospital of Philadelphia that focuses on genomics research and the utilization of basic research findings in the development of new medical treatments.
3q29 microdeletion syndrome is a rare genetic disorder resulting from the deletion of a segment of chromosome 3. This syndrome was first described in 2005.
Non-allelic homologous recombination (NAHR) is a form of homologous recombination that occurs between two lengths of DNA that have high sequence similarity, but are not alleles.
1q21.1 deletion syndrome is a rare aberration of chromosome 1. A human cell has one pair of identical chromosomes on chromosome 1. With the 1q21.1 deletion syndrome, one chromosome of the pair is not complete, because a part of the sequence of the chromosome is missing. One chromosome has the normal length and the other is too short.
1q21.1 copy number variations (CNVs) are rare aberrations of human chromosome 1.
Chromosomal deletion syndromes result from deletion of parts of chromosomes. Depending on the location, size, and whom the deletion is inherited from, there are a few known different variations of chromosome deletions. Chromosomal deletion syndromes typically involve larger deletions that are visible using karyotyping techniques. Smaller deletions result in Microdeletion syndrome, which are detected using fluorescence in situ hybridization (FISH)
Neuroblastoma breakpoint family, member 1, or NBPF1, is a protein that is encoded by the gene NBPF1 in humans. This protein is member of the neuroblastoma breakpoint family of proteins, a group of proteins that are thought to be involved in the development of the nervous system.
The neuroblastoma breaking point family (NBPF) is a family of genes involved in neuronal development. The family is highly specific to primates, with minimal similarity or presence in other mammals and no presence in other animals, and its genes' content has been subject to a very high number of duplications in humans. It was described by Vandepoele et al. in 2005 and named as such because NBPF1 was found to be broken by a chromosomal translocation in a neuroblastoma patient.
17q12 microdeletion syndrome, also known as 17q12 deletion syndrome, is a rare chromosomal anomaly caused by the deletion of a small amount of material from a region in the long arm of chromosome 17. It is typified by deletion of the HNF1B gene, resulting in kidney abnormalities and renal cysts and diabetes syndrome. It also has neurocognitive effects, and has been implicated as a genetic factor for autism and schizophrenia.
Syndromic autism denotes cases of autism spectrum disorder that are associated with a broader medical condition, generally a syndrome. Cases without such association, which account for the majority of total autism cases, are known as non-syndromic autism.
16p11.2 deletion syndrome is a rare genetic condition caused by microdeletion on the short arm of chromosome 16. Most affected individuals experience global developmental delay and intellectual disability, as well as childhood-onset obesity. 16p11.2 deletion is estimated to account for approximately 1% of autism spectrum disorder cases.
