Recently (2008), it was shown that the conditional deletion of Mecp2 in catecholaminergic neurons (by crossing of Th-Cre mice with loxP-flanked Mecp2 ones) recapitulates a motor symptomatology, it was further documented that brain levels of Th in mice lacking MeCP2 in catecholaminergic neurons only are reduced, participating to the motor phenotype.However, the most studied model for the evaluation of therapeutics is the Mecp2-null mouse (totally devoid of MeCP2). In this context, a reduction in the number and soma size of Th-expressing neurons is present from 5 weeks of age and is accompanied by a decrease of Th immunoreactivity in the caudate-putamen, the principal target of dopaminergic neurons arising from the SNpc. Moreover, a neurochemical analysis of dopaminergic contents in microdissected midbrain and striatal areas revealed a reduction of dopamine at five and nine weeks of age. It is noteworthy that later on (at nine weeks), the morphological parameters remain altered but not worsen, whereas the phenotype progresses and behavioral deficits are more severe. The amount of fully activated Th (Serine40-phosphorylated isoform) in neurons that remain in the SNpc is mildly affected at 5 weeks but severely impaired by 9 weeks. Finally, using a chronic and oral L-Dopa treatment on MeCP2-deficient mice authors reported an amelioration of some of the motor deficits previously identified. Altogether, these results argue for an alteration of the nigrostriatal dopaminergic pathway in MeCP2-deficient animals as a contributor of the neuromotor deficits.There is an association of the disease with brain-derived neurotrophic factor (BDNF).
Most of time chromosome 9p deletion syndrome is diagnosed after birth by the detection of symptoms via clinical evaluation. Common methods used to detect Monosomy 9p after birth include the use of a stethoscope, X-ray, and EKG. Monosomy 9p is also diagnosed before birth by ultrasound, amniocentesis, and chorionic villus sampling (CVS). Ultrasound can hint at the malformations of the face, limbs, and heart. While amniocentesis and CVS both use fluid and tissue to perform chromosomal studies to identify chromosomal abnormalities. Finally, karyotyping, a procedure used to examine a patients chromosomes, can be used to diagnose Monosomy 9p both before birth and after birth. Management
Treatment of Monosomy 9p focuses mainly on fixing the malformations. For example, to fix facial malformations, physicians can perform facial surgery to repair the facial malformations. This can open airways for the infant or patient; especially the nose-to-throat pathway. Similarly, to fix heart malformations, physicians can recommend surgery or medication to improve the efficiency of the pumping of the heart. Lastly remedial education, speech therapy, and physical therapy can be used to improve the developmental delay associated with the syndrome. Epidemiology
Chromosome 9p deletion syndrome occurs 1 in 50,000 births. Half of the cases occur sporadically, while the other half of cases result from parent translocations or the parent having deletion as well. References


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