The condition is described as the embryonic forebrain and the faces of human babies. The etiology is heterogeneous genetically and therefore is passed from parents to offsprings. It may also have some environmental inclination (Mallick et al, 2014, para 1). HPE is subdivided into four classes ranging from the least to the most severe kind (Nanni, Schelper & Muenke, 2010, para 2). The brain is bifurcated into two hemispheres. Only 3% of the fetuses develop to delivery. Two-thirds of the affected develop alobar HPE. Which is the most severe of them.
The prevalence of the condition has been quoted as 1 in every 250 embryos that are delivered annually. 1 of 10000 live-born infants less than 1:100,000 over one year (Muenke, 2008). The causes of the disorder are cytogenetic anomalies, gene mutations, defects of cholesterol Biosynthesis and finally gene/ environmental interactions. The predisposing factors have been questioned to be low maternal cholesterol or mothers who have diabetes. Alcoholics also have a higher chance of developing the condition as well as retinoic acid exposure.
Genetics
On the third week of embryonic changes. The mesoderm moves to the area where the notochord and midline facial growth. The phenotype of HPE is different for different people. In only 70-80% of the time is the saying that the face predicts the location of the brain (Hahn, Lauren & Plawner 2004)).
Sin Qua nonfeature is the incomplete separation of the hemispheres of the brain also known as alobar HPE. This type has a singular separating cranial line. Therefore, it is mono ventricular cerebrum. It develops a dorsal cyst that communicates with the brain in the absence of corpus callosum and interhemispheric fissures. Semi lobar HPE is a kind that is less severe than alobar. The difference is that it only has a defect in the frontal lobe. The occipital area has features of the development of separation. On the anterior the corpus is not visible while in the posterior aspect it is present. The mild form of HPE is lobar. Only the ventral aspect is not separated. The rest of the brain is well separated completely. The defect is not easy to visualize and may be missed in diagnostic procedures (Hahn, Lauren & Plwner, 2004, p. 79)
Molecular and Functional Consequences of Aberration
Molecular studies indicate that the fetus that develops HPE have a sequential deletion of the genes. 14% have the changes happening in four main classifications SHH, ZIC2, SIX3 and TGIF (Bendavid et al.,2005, para 2). Mutation studies show that HPE is as a result of genetic loss or mutational dysfunction action of loci which is a core factor in human creation (Roessler & Muenke, 2010, p. 52).
Diagnosis
An early ultrasound can be used to detect the condition. It gives a visualization of the features of the baby. Unlike other tests such as amniocentesis. The scan can be done at 14 weeks. It can be done by either be transabdominal or transvaginal (Chang, 2003). A CT scan can be done to examine the bone formation in the brain. To help identify if the fetus will develop the condition. MRI however, is the most preferred test. It gives a clearer visual dimension of the brain. It also identifies any other associated anomalies (Solomon, Gropman & Muenke, 2013. Para 2). Gonadotropic releasing hormone deficiency is highly associated with the allele that causes HPE, which affects the FGF8 gene in early human formation.
Management
The prognosis of the condition is poor in most cases. Only the ones that develop the milder forms such as lobar have a chance of survival. Most of the infants that suffer from alobar have reduced chances of surviving past the postnatal duration. Due to the complications that arise The babies that develop endocrine problems they are at high chances of getting diabetes insipidus (Traggiai & Stanhope, 2002, p. 252). They are therefore on prescription for treatments of diabetes. Gastrostomy tube is inserted for babies who develop gastrointestinal complications to help them with excretion of waste matte (Levey, et al. 2010.p. 185). The babies have to be given treatment for heartburn to prevent the pain related to gastroesophageal reflux. To prevent the risk of convulsions they also have to take anticonvulsants. And Botulinum toxin is indicated for muscle relaxation (Dubourg et al. 2007.para 3).
Conclusion
It is significant that the pediatrician and the parent be the followers of the prescribed protocol. The sure way to improve the prognosis of the condition by identifying the risk factors prenatally. Then carrying out the proper diagnosis measures during the pregnancy to ascertain the need to terminate the pregnancy or the chance of survival about the severity of the condition. Some of the complications that may occur t such infants are endocrinology disorders, where hormonal imbalances are prevalent. Hypothalamic problems make it difficult to control temperatures for the newborn. Motor impairment is highly prone. The babies may not be able to develop motor functions as expected (Muenke, Raam & Solomon, 2011.P. 2).
References
Arauz, R.F. et al. 2010. A Hypomorphic Allele in the FGF8 Gene Contributes to HPE and is Allelic to Gonadotrophin-Releasing Hormone Deficiency in Humans. http://www.ncbi.nlm.nih.gov/pubmed/21045958
Bendavid, C. et al. 2005. Molecular Evaluation of Fetuses with Holoprosencephaly Shows High Incidence of Microdeletions in the HPE. Genes. PubMed. http://www.ncbi.nlm.nih.gov/pubmed/16323008
Chang. 2003. Alobar Holoprosencephaly: Report of Two Cases with Unusual Findings. Department of Pediatrics, Taichung Hospital.26:9
Dubourg, C. et al. 2007. Holoprosencephaly. OrnetJ Rare Dis. 2-2:8
Hahn, S. J., Lauren, L. & Plawner, L. 2004. Evaluation and Management of Children with Holoprosencephaly. Pediatric Neurol. Elsevier.
Levey, E. B. 2010. Management of Children with Holoprosencephaly. American Journal of Medical Genetics Part C. 154C:183-190
Mallick, S. 2014. Semi lobar Holoprosencephaly with 21q22 Deletion: An Autopsy Report. PubMed. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3962924/
Muenke, M. 2008. Holoprosencephaly. Second European Course in Clinical Dysmorphology. http://istituti.unicatt.it/genetica-medica-MaxMuenke.pdf
Muenke, M., Solomon, B. & Raam, M.S. 2011. Holoprosencephaly: A Guide to Diagnosis and Clinical Management. Indian Pediatr.NIH Public Access.
Muenke, M. & Rossler, E. 2010. The Molecular Genetics of Holoprosecephaly. American Journal of Medical Genetics. 154C:1 P. 52-61
Nanni, L., Schelper, L.R. & Muenke, M. 2010. Molecular Genetics of Holoprosencephaly. Pediatric Pathology & Molecular Medicine.19:1
Traiggaiai, C. & Stanhope, R. 2002.Endocrinopathies Associated with Midline Cerebral and Cranial Malformations. JPediatr. https://www.researchgate.net/publication/11497390_Endocrinopathies_associated_with_ midline_cerebral_and_cranial_malformations_J_Pediatr
Wellness. 2016. Holoprosencephaly(HPE) Prevention and Treatment. Wellness http://www.wellness.com/reference/conditions/holoprosencephaly-hpe/prevention-and- treatment.
