Introduction to Human Cytochrome P450 Superfamily
Shufeng Zhou in Cytochrome P450 2D6, 2018
CYP26A1 maps to chromosome 10q23–24 and has eight exons (White et al. 1998). The CYP26A1 gene is conserved in chimpanzee, rhesus monkey, dog, cow, mouse, rat, chicken, zebra-fish, A. thaliana, rice, and frog. Several disease-related loci including hand-split foot and infantile onset spinocerebellar atrophy have also been mapped to this region. In humans, a syndrome known as caudal regression syndrome is characterized by congenital sacral agenesis and involvement of the nervous, urinary, and gastrointestinal systems (De Marco et al. 2006). CYP26A1 (also called retinoic acid 4-hydroxylase) has been detected in different cell lines with different tissue origins including kidney, liver, breast, intestine, and lung. It is also expressed in fetal liver and brain tissue. Cyp26a1 is expressed early in the mouse embryo in a stage- and region-specific manner: in the neural plate, neural crest cells for the cranial ganglia, hindgut, and tailbud mesoderm (Fujii et al. 1997). atRA is converted to less active and more polar 4-OH, 4-oxo, 16-OH, and 18-OH metabolites by CYP26A1 (Thatcher et al. 2011), but the biological role of atRA metabolites is largely unknown. 9-cis-RA and 13-cis-RA are also substrates of CYP26A1. atRA, 4-OH-atRA, 18-OH-atRA, and 4-oxo-atRA are substrates of CYP26A1, forming a variety of biologically inactive diols and oxo-alcohols from these metabolites (Topletz et al. 2015). Cyp26a1-deficient mice die during mid-late gestation, with spina bifida, severe caudal agenesis, abnormalities of the kidneys and hindgut, and hindbrain (Abu-Abed et al. 2001; Fujii et al. 1997). These findings indicate that CYP26A1 protects fetal brain and other tissues from excess RA, which is teratogenic (Pennimpede et al. 2010).
Neuromuscular disorders
Ashley W. Blom, David Warwick, Michael R. Whitehouse in Apley and Solomon’s System of Orthopaedics and Trauma, 2017
Sacral agenesis or caudal regression syndrome is a very rare congenital disorder in which there is abnormal development of the lower spine (the caudal partition of the spine) and other organ systems in the lower half of the body such as the urogenital and gastrointestinal systems (Figure 10.33). The lower-limb function depends to a large extent on the severity of the neurological developmental problem. Some patients can walk and may behave much like a low-level spina bifida but others with major anomalies may have an absent sacrum and lower lumbar spine with legs fixed in a ‘Buddha position’.
Fetal malformations detected with magnetic resonance imaging in the diabetic mother
Moshe Hod, Lois G. Jovanovic, Gian Carlo Di Renzo, Alberto de Leiva, Oded Langer in Textbook of Diabetes and Pregnancy, 2018
Fetal caudal regression syndrome is usually detected by screening ultrasound examination. It has a typical sonographic finding of a sudden interruption of the spine with absent or hypoplastic sacrum. Associated malformations of the lower extremities, such as hypoplastic limbs and sirenomelia, are common. The legs of the fetus may be consistently crossed. MRI can confirm these ultrasound findings by its clearer soft tissue definition. It can also be used to assess the stenosis of the spinal canal, which can predict the degree of neurological deprivation.26
Pseudo-Roberts Syndrome: An Entity or Not?
Published in Fetal and Pediatric Pathology, 2022
Behzad Salari, Louis P. Dehner
Poor control of maternal diabetes may have a profound teratogenic effect at early stages of embryogenesis. Infants of diabetic mothers are at risk for a multitude of congenital complications including preterm birth and congenital anomalies [14]. Cardiac abnormalities include asymmetric septal hypertrophy, transient hypertrophic subaortic stenosis, and/or a thickened myocardium. The risk of central nervous system malformations, and more specifically, caudal dysplasia is high (up to 600 times higher in the latter). Caudal regression syndrome represents a spectrum of clinical phenotypes characterized by varying degrees of malformation of cardiovascular system (hypoplasia), and the lower body including the vertebral column and spinal cord (spina bifida), anorectal malformations, and lower limbs including total or partial sacral agenesis and a single midline femur and tibia [15].
Sirenomelia and maternal chlamydia trachomatis infection: a case report and review
Published in Fetal and Pediatric Pathology, 2019
Gabriella Fuchs, Ekaterina Dianova, Sunny Patel, Sonia Kamanda, Rita Prasad Verma
Although sirenomelia sequence presents with anomalies that are almost always incompatible with survival, prognosis might improve in cases with less severe urogenital defects and the consequent milder lung hypoplasia [1]. Few cases of sirenomelia with minimal renal abnormalities or even normal kidneys have been reported who survived beyond the newborn period [15]. These cases belonged to caudal regression or VACTREL anomaly sequence which are now considered to be milder forms of sirenomelia [6]. In caudal regression syndrome the lower vertebrae, but not the extremities, are fused with genitourinary and gastrointestinal anomalies [26]. Stocker and Heifetz created a classification system in 1987, which mentions seven types based on severity of tibial fusion as seen on radiology and autopsy [6,17]. Our case had a classic clinical presentation of the disorder, belonging to type IV category according to the classification, and like majority of such cases, the infant expired shortly after birth.
Related Knowledge Centers
- Birth Defect
- Diabetes
- Hypoplasia
- Lumbar Vertebrae
- Mutation
- Vertebral Column
- Coccyx
- Sacrum
- Prenatal Development
- Currarino Syndrome