Journal: Journal of medical genetics
Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessiveTK2mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy.
Fabry disease is an X-linked lysosomal storage disorder caused by GLA mutations, resulting in α-galactosidase (α-Gal) deficiency and accumulation of lysosomal substrates. Migalastat, an oral pharmacological chaperone being developed as an alternative to intravenous enzyme replacement therapy (ERT), stabilises specific mutant (amenable) forms of α-Gal to facilitate normal lysosomal trafficking.
The 11p15 region is organised into two independent imprinted domains controlled by imprinting control regions, which carry opposite germline imprints. Dysregulation of 11p15 genomic imprinting results in two human fetal growth disorders (Silver-Russell syndrome (SRS, MIM 180860) and Beckwith-Wiedemann syndrome (BWS, MIM 130650)) with opposite growth phenotypes. The mouse orthologous region on distal chromosome 7 (dist7) is well conserved in its organisation and its regulation. Targeted mutagenesis in mice has provided highly valuable clues in terms of the mechanisms involved in the regulation of genomic imprinting of the 11p15/dist7 imprinted region. On the other hand, the recent identification of unexpected genetic defects in BWS and SRS patients also brought new insights into the mechanisms of 11p15 imprinting regulation. However, some mouse models and human genetic defects show contradictions in term of growth phenotypes and parental transmission. In this review, we extensively analyse those various mouse and human models and more particularly models with mutations affecting the two imprinting centres, in order to improve our understanding of regulation of 11p15/dist7 genomic imprinting.
Autosomal recessive hereditary spastic paraplegias (AR-HSP) constitute a heterogeneous group of neurodegenerative diseases involving pyramidal tracts dysfunction. The genes responsible for many types of AR-HSPs remain unknown. We attempted to identify the gene responsible for AR-HSP with optic atrophy and neuropathy.
Inherited CDKN2A mutation is a strong risk factor for cutaneous melanoma. Moreover, carriers have been found to have poor melanoma-specific survival. In this study, responses to novel immunotherapy agents in CDKN2A mutation carriers with metastatic melanoma were evaluated.
Retinitis pigmentosa (RP) is the most frequent inherited retinal disease, which shows a relatively high incidence of the autosomal-recessive form in Pakistan.
Opitz G/BBB syndrome is a heterogeneous disorder characterised by variable expression of midline defects including cleft lip and palate, hypertelorism, laryngealtracheoesophageal anomalies, congenital heart defects, and hypospadias. The X-linked form of the condition has been associated with mutations in the MID1 gene on Xp22. The autosomal dominant form has been linked to chromosome 22q11.2, although the causative gene has yet to be elucidated.
Osteonecrosis of the femoral head is a debilitating disease that involves impaired blood supply to the femoral head and leads to femoral head collapse.
Several recessive Mendelian disorders are common in Europeans, including cystic fibrosis (CFTR), medium-chain-acyl-Co-A-dehydrogenase deficiency (ACADM), phenylketonuria (PAH) and alpha 1-antitrypsin deficiency (SERPINA1).
BACKGROUND: Congenital multiple intestinal atresia (MIA) is a severe, fatal neonatal disorder, involving the occurrence of obstructions in the small and large intestines ultimately leading to organ failure. Surgical interventions are palliative but do not provide long-term survival. Severe immunodeficiency may be associated with the phenotype. A genetic basis for MIA is likely. We had previously ascertained a cohort of patients of French-Canadian origin, most of whom were deceased as infants or in utero. The goal of the study was to identify the molecular basis for the disease in the patients of this cohort. METHODS: We performed whole exome sequencing on samples from five patients of four families. Validation of mutations and familial segregation was performed using standard Sanger sequencing in these and three additional families with deceased cases. Exon skipping was assessed by reverse transcription-PCR and Sanger sequencing. RESULTS: Five patients from four different families were each homozygous for a four base intronic deletion in the gene TTC7A, immediately adjacent to a consensus GT splice donor site. The deletion was demonstrated to have deleterious effects on splicing causing the skipping of the attendant upstream coding exon, thereby leading to a predicted severe protein truncation. Parents were heterozygous carriers of the deletion in these families and in two additional families segregating affected cases. In a seventh family, an affected case was compound heterozygous for the same 4bp deletion and a second missense mutation p.L823P, also predicted as pathogenic. No other sequenced genes possessed deleterious variants explanatory for all patients in the cohort. Neither mutation was seen in a large set of control chromosomes. CONCLUSIONS: Based on our genetic results, TTC7A is the likely causal gene for MIA.