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Paediatric clinical pharmacology
Published in Evelyne Jacqz-Aigrain, Imti Choonara, Paediatric Clinical Pharmacology, 2021
Evelyne Jacqz-Aigrain, Imti Choonara
This polymorphism is inherited through an autosomal recessive gene. Homo-zygous individuals are characterised by negligible or no metabolism of a variety of drugs [8]. Several β-adrenoceptor-blocking agents, antidepressants, and anti-arrythmic drugs belong to this group. Using dextromethorphan as a marker for CYP2D6 activity, the ontogenesis of the enzyme activity was examined in hepatic tissue samples from human fetuses, newborns and children [9]. CYP2D6 activity was not detectable in the fetus, increased rapidly during the postnatal period, independently of gestational age, but remained low during the first month of life (about 20% of adults levels). These data are consistent with the lack of CYP2D6 mediated O-demethylation despite catalytic CYP3A mediated N-demethylation of codeine [3] in human fetal liver. Phenotypic studies conducted in small populations of children, have shown that the adult phenotypic distribution pattern was attained at 3 years of age [10].
The Asebia (ab, abJ) Mutations, Chromosome 19
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
The original asebia (symbol ab) mutation arose spontaneously in a colony of BALB/cCrglGa mice. It was shown to be an autosomal recessive gene with complete penetrance. Mutant mice were then inbred and maintained on a background designated BALB/cGa +/ab.1 A similar mutation arose spontaneously in the BALB/cJ inbred strain at die Jackson Laboratory in 1968. One outcross was made to C3H/HeDi; then backcrosses were bred. Allelism with αb was proven by Dr. S. J. Mann. The remutation, abJ was mapped to Chromosome 19.2 AsebiaJ is maintained as an inbred strain ABJ/Le.3 Abnormalities of the sebaceous glands appear to be the same between the two mutations.4 The asebia mutation is autosomal recessive and maps to mouse Chromosome 19 (Figure 1).2
Cystic Fibrosis
Published in Stephen D. Litwin, Genetic Determinants of Pulmonary Disease, 2020
Alexander G. Bearn, Β. Shannon Danes
In summary, the genetic evidence is overwhelming that CF is caused by an autosomal recessive gene but the possibility that the disease is heterogeneous still exists. This is based not only on the increasing evidence that nearly all inherited diseases are heterogeneous, but also on the evidence that there is cellular and biochemical heterogeneity.
Pathogenic gene variants identified in patients with retinitis pigmentosa at the referral center clinic of the University of Minnesota (UMN)
Published in Ophthalmic Genetics, 2023
Richard Sather, Jacie Ihinger, Tahsin Khundkar, Sandra R. Montezuma
With reference to Figure 1, there were 58/127 (45.7) patients in our cohort that did not have a diagnostic pathogenic variant identified who underwent genetic testing. 22/127 (17.3%) patients had only VUS (column 2) and 8/127 (6.3%) had negative results (column 3). For the remaining 28 patients (columns 1b and 1c), they had a pathogenic variant identified, but were not diagnostic for two reasons. For the 13/127 patients (column 1b), only one known pathogenic variant was found, while the corresponding allele was classified as VUS. To meet diagnostic criteria, both alleles must be identified as pathogenic and cis/trans configuration must be determined. The second reason was that the other 15/97 patients (column 1c) had a single pathogenic variant identified in an autosomal recessive gene. These patients would be considered asymptomatic carriers for that disease, and testing was otherwise non-diagnostic.
Combined X-linked familial exudative vitreoretinopathy and retinopathy of prematurity phenotype in an infant with mosaic turner syndrome with ring X chromosome
Published in Ophthalmic Genetics, 2023
Sandra Hoyek, Marlene Wang, Audina M. Berrocal, Ashley Wong, Emily M. Place, Heather Mason-Suares, Angela E. Lin, Shizuo Mukai, Nimesh A. Patel
There were no disease-causing sequence variants in the genes analyzed, although a heterozygous variant of uncertain significance in the autosomal recessive gene P3H2 (c.385 G>T, p.(Gly129Trp)) was detected. The targeted NGS gene panel results did, however, detect mosaic possible monosomy X and ring X, which is associated with Turner syndrome. NGS read data suggested approximately 46% of cells had a missing X chromosome, and approximately 54% of cells had 1 to 2 copies of the estimated genomic region of chrX: 46513221–117959147, consistent with mosaicism involving a ring X chromosome with breakpoints at Xp11.23 and Xq24. The estimated genomic region deleted in the presumed ring X encompassed two genes associated with inherited vitreoretinopathies, NDP and RS1. Subsequent chromosome analysis by karyotype on peripheral blood sample detected 45,X in eight out of 20 cells (40%) and a 46,X,r(X) in 12 out of 20 (60%) cells (Figure 2). Furthermore, chromosomal microarray analysis refined the breakpoints, demonstrating that the mosaic ring X chromosome is composed of material from band p11.23 to band q23, including the X-inactive specific transcript (XIST) gene. The size of the ring X is approximately 69.8 Mb, which we estimate to be a medium-to-large sized ring. Thus, chromosome analysis and microarray testing confirmed the diagnosis of mosaic Turner syndrome.
UK guidelines for the medical and laboratory procurement and use of sperm, oocyte and embryo donors (2019)
Published in Human Fertility, 2021
Helen Clarke, Shona Harrison, Marta Jansa Perez, Jackson Kirkman-Brown
Furthermore, the potential donor should ordinarily not be heterozygous for an autosomal recessive gene known to be prevalent in the donor’s ethnic background. This includes: (i) cystic fibrosis in Caucasian populations; (ii) glucose-6-phosphate dehydrogenase deficiency or ∝0 or β-Thalassaemia in Mediterranean populations; (iii) sickle cell disease in African & Afro-Caribbean populations; and (iv) Tay-Sachs disease in Jews of Eastern European descent. However, in exceptional circumstances (e.g. in cases of known donation) the presence of a recessive gene disorder may not necessarily be a contraindication to donation provided that, when the donation is used, all parties are fully informed, the view of an appropriately qualified clinical geneticist is obtained and full records are kept. The decision whether or not to proceed should consider the type of treatment being offered as well as the genetic profile of the donor and recipient couple.