Clinical and genetic characterization of patients segregating variants in KPTN, MINPP1, NGLY1, AP4B1, and SON underlying neurodevelopmental disorders: Genetic and phenotypic expansion.

Neurodevelopmental disorders (NDDs) are heterogeneous genetic conditions of the central nervous system (CNS). Primary phenotypes of NDDs include epilepsy, loss of developmental skills, abnormal movements, muscle weakness, ocular anomalies, hearing problems, and macro- or microcephaly. NDDs occur due to variants in genes encoding proteins involved in the structure and function of CNS, thus interrupting its normal physiological role. In the study presented here, four consanguineous families (A-D), with members showing neurodevelopmental symptoms, were recruited for clinical and genetic characterization of the phenotypes. Clinical examinations, including Seguin Form Board Test (SFBT), Vineland Social Maturity Scale (VSMS), brain Magnetic Resonance Imaging (MRI), Electroencephalogram (EEG), Electromyography (EMG), Nerve Conduction Velocity (NCV), and Magnetic Resonance Spectroscopy, were employed to characterize the disease phenotypes. Whole exome sequencing (WES) followed by Sanger sequencing was employed to search for the genetic basis of the neurological symptoms observed in four families (A-D). Two of these families (A, B) were of Saudi Arabian origin, and two others (C, D) were of Pakistan origin. Two homozygous missense (KPTN: NM_007059.4:c.301T>G: NP_008990.2; p.(Phe101Val) and MINPP1:NM_001178118.2:c.1202G>A: NP_001171588.1; p.(Arg401Gln)) variants in families A and B, respectively, and two homozygous nonsense (NGLY1:NM_018297.3:c.1534_1541dup: NP_060767.2; p.(Ser515LysfsTer51) and AP4B1:NM_001253852:c.1668G>A: NP_001240781.1; p.(Trp556X)) variants in families C and D, respectively, were identified. Interestingly, additional heterozygous nonsense variant in SON: NM_138927.2: c.5753_5756del: NP_620305.3; p.(Val1918GlufsTer87) and a homozygous variant in FLG (FLG: NM_002016.2:c.7339C>T: NP_002007.1; p.(Arg2447X) were detected in families A and D, respectively. Further, we determined the deleteriousness of each variant through computational approaches. The present study expands the phenotypic and genetic spectrum of NDD-associated genes (KPTN, MINPP1, NGLY1, and AP4B1). Moreover, additional nonsense variants (SON: c.5753_5756del and FLG: c.7339C>T) identified in two families segregating with the phenotype might explain the phenotypic variability and severity in our patients.

Prevalence of nonaffective psychosis in intellectually disabled clients: systematic review and meta-analysis.

Epidemiological studies report high rates of schizophrenia in individuals with intellectual disability (ID). However, this subject has not been reviewed systematically. We aim to review studies that report the prevalence of nonaffective psychosis in a population with ID and estimate the prevalence of schizophrenia in this population. We performed a literature search using the PsychINFO, MEDLINE and EMBASE (from inception to 2 October 2014). We performed a manual search of citations from relevant papers identified through the databases. We identified 887 titles and after screening abstracts, identified 60 full-text articles. We identified 25 studies with 27 datasets for inclusion in the systematic review and meta-analysis. The prevalence rate was at least three times higher than the general population. There was a wide variation in the methodology, setting and sample size of the studies. Only one study reported a prevalence rate lower than the general population. The prevalence of psychosis in a population with ID is at least three times higher than that in the general population.