Microcephaly, Short Stature, Intellectual Disability, Speech Absence and Cataract Are Associated with Novel Bi-Allelic Missense Variant in RTTN Gene: A Seckel Syndrome Case Report

Clinical Challenges in Diagnosing Primordial Dwarfism: Insights from a MOPD II Case Study

Background and Objectives.Primordial dwarfism (PD) is a rare group of genetic conditions where individuals experience severe growth restriction, both in the womb and after birth. From as early as the fetal stage, those affected are significantly smaller than their peers. What makes PD distinct is its slow but steady growth pattern, resulting in proportionate dwarfism, where all parts of the body are equally shortened. Diagnosing and managing PD presents significant challenges due to its rarity and the wide range of clinical and genetic variability. The main conditions in this group include Seckel syndrome, Microcephalic Osteodysplastic Primordial Dwarfism (MOPD) types I/III, MOPD type II, Meier-Gorlin syndrome, and Silver-Russell syndrome (SRS). The first four-Seckel syndrome, MOPD types I/III, MOPD type II, and Meier-Gorlin syndrome-are associated with microcephaly, and together they are known as microcephalic PD. Given how uncommon PD is, establishing its exact incidence is difficult. It is estimated that about 4 million infants die within the first month of life, with 99% of these deaths occurring in the neonatal period. Materials and Methods. Accurately diagnosing PD requires meticulous evaluation, as it can be easily confused with other genetic disorders that also cause dwarfism. In this article, we present the case of a 10-year-old patient diagnosed with MOPD II, the most common and well-documented form of microcephalic PD. Results. Genetic analysis revealed a pathogenic variant in the PCNT (pericentrin) gene ((c.1550dup, p.Gln518Alafs*7), alongside a deletion of exons 37-41. Conclusions. This case sheds light on the clinical and genetic complexities of primordial dwarfism, underscoring the importance of timely and accurate diagnosis for effective patient care.

Genomic Regions Associated with Growth and Reproduction Traits in Pink-Eyed White Mink

In mink breeding, balanced selection for growth and reproductive features is essential because these traits are contradictory. The variables of total number born (TNB), number born alive (NBA), and body weight (BW) are highly valuable in terms of their importance in mink production. A comprehensive understanding of the molecular mechanisms that drive these features could offer vital insights into their genetic compositions. In the present study, the single-nucleotide polymorphism (SNP) genotypes of 219 minks were obtained via double digest restriction-site associated DNA sequencing (ddRAD-seq). Following several rounds of screening, about 2,415,121 high-quality SNPs were selected for a genome-wide association study (GWAS). The GWAS was used to determine BW and reproductive traits in pink-eyed white mink. It was suggested that SLC26A36, STXBP5L, and RPS 29 serve as potential genes for the total number of kits born (TNB), while FSCB, PDPN, NKX 2-1, NFKB 1, NFKBIA, and GABBR1 are key genes for the number born alive (NBA). Moreover, RTTN, PRPF31, MACROD1, and KYAT1 are possible BW genes based on association results and available functional data from gene and mammalian phenotype databases. These results offer essential information about the variety of mink and theoretical principles for applying mink breeds.

Clinical genomics expands the link between erroneous cell division, primary microcephaly and intellectual disability

Primary microcephaly is a rare neurogenic and genetically heterogeneous disorder characterized by significant brain size reduction that results in numerous neurodevelopmental disorders (NDD) problems, including mild to severe intellectual disability (ID), global developmental delay (GDD), seizures and other congenital malformations. This disorder can arise from a mutation in genes involved in various biological pathways, including those within the brain. We characterized a recessive neurological disorder observed in nine young adults from five independent consanguineous Pakistani families. The disorder is characterized by microcephaly, ID, developmental delay (DD), early-onset epilepsy, recurrent infection, hearing loss, growth retardation, skeletal and limb defects. Through exome sequencing, we identified novel homozygous variants in five genes that were previously associated with brain diseases, namely CENPJ (NM_018451.5: c.1856A > G; p.Lys619Arg), STIL (NM_001048166.1: c.1235C > A; p.(Pro412Gln), CDK5RAP2 (NM_018249.6 c.3935 T > G; p.Leu1312Trp), RBBP8 (NM_203291.2 c.1843C > T; p.Gln615*) and CEP135 (NM_025009.5 c.1469A > G; p.Glu490Gly). These variants were validated by Sanger sequencing across all family members, and in silico structural analysis. Protein 3D homology modeling of wild-type and mutated proteins revealed substantial changes in the structure, suggesting a potential impact on function. Importantly, all identified genes play crucial roles in maintaining genomic integrity during cell division, with CENPJ, STIL, CDK5RAP2, and CEP135 being involved in centrosomal function. Collectively, our findings underscore the link between erroneous cell division, particularly centrosomal function, primary microcephaly and ID.

Investigating the effects of a single ASPM variant (c.8508_8509) on brain architecture among siblings in a consanguineous Pakistani family

BACKGROUND

Autosomal Recessive Primary Microcephaly (MCPH) is a rare, neurodevelopmental disorder associated with mild to severe mental retardation. It is characterized by reduced cerebral cortex that ultimately leads to reduction in skull size less than - 3 S.D below the mean for normal individuals having same age and sex. Till date, 30 known loci have been reported for MCPH.

METHODS

In the present study, Sanger sequencing was performed followed by linkage analysis to validate the mutation in ASPM gene of the consanguineous Pakistani clans. Bioinformatics tools were also used to confirm the pathogenicity of the diseased variant in the gene. MRI scan was used to compare the brain structure of both the affected individuals (Aslam et al. in Kinnaird's 2nd International Conference on Science, Technology and Innovation, Lahore, 2023).

RESULTS

Our study described a consanguineous family with two patients with a known ASPM (MCPH5) variant c.8508_8509delGA causing a frameshift mutation in exon 18 which located in calmodulin-binding IQ domain of the ASPM protein. The salient feature of this study is that a single variant led to significantly distinct changes in the architecture of brain of both siblings which is further confirmed by MRI results. The computation analysis showed that the change in the conservation of this residue cause this variant highly pathogenic. Carrier screening and genetic counselling were also remarkable features of this study (Aslam et al. in Kinnaird's 2nd International Conference on Science, Technology and Innovation, Lahore, 2023).

CONCLUSION

This study explores the extraordinary influence of a single ASPM variant on divergent brain structure in consanguineous siblings and enable us to reduce the incidence of further microcephalic cases in this Pakistani family (Aslam et al. in Kinnaird's 2nd International Conference on Science, Technology and Innovation, Lahore, 2023).