Intellectual disabilities (ID) are among the most common genetic disabilities
worldwide. Over the last two decades, ID has especially drawn special scientific
interest being the key to understanding normal brain development, growth, and
functioning. Here, we discuss two intellectual disabilities to better understand the
emerging trends in disease diagnosis as well as the therapies available for their
management. Primary microcephaly (MCPH) is a monogenic genetic disorder with
twenty-eight loci (MCPH1-MCPH28) mapped so far with all the causative genes being
elucidated as well. The role of these genes in disease prognosis along with their
association with various MCPH-linked phenotypes plays an important role in the
molecular diagnosis of the disease. As there is no cure/treatment yet available to
enlarge a congenitally small brain, management modalities in use include physical,
speech and occupational therapies as well as psychological and genetic counselling to
not only reduce the incidence of the disorder but also to help families cope better. The
second intellectual disability being discussed here is schizophrenia which is a
multifactorial disorder owing to its complex and extremely heterogeneous etiology.
Although various environmental factors play an important role, the genetic factors have
been identified to play the most pivotal role in disease presentation as to date, 19 loci
(SCZD1-SCZD19) have been linked to schizophrenia. However, underlying genes for
only six of these loci have been mapped along with 10 other genes that are either linked
to schizophrenia or show susceptibility to it. Diagnosis of schizophrenia needs careful
consideration and various tests and tools currently employed for complete diagnosis
have been discussed here. The management options for schizophrenia include
pharmacological, non-pharmacological and intracranial therapies. These disorders shed
light on the important role omics technologies have played not only in better
understanding of the disease prognosis but also assisting in disease diagnosis and
treatment modalities too.
Keywords: Cortical development, Dopamine pathways, Genetic heterogeneity, Genotype-phenotype associations, Occipitofrontal head circumference (OFC), Primary microcephaly (MCPH), Schizophrenia.
