These are present in different structures that make it up, such as heart valve defects, the presence of Fallots tetralogy, atrial septal defects or persistent truncus arteriosus. Other alterations described are craniofacial anomalies associated with hypoplasia of the midface, hypertelorism, telecanthus, maxillary hypoplasia, short nasolabial fold, thin upper lip and larger everted lower lip, which are typical facial characteristics although expressed in a variable way. Maxillary hypoplasia and poor tooth development produce a prognathic profile. Inspection of the oral cavity may show microdontia, hypodontia, oligodontia, and a thickened frenulum. The crowns of the anterior teeth may be conical or peg-shaped and the roots may be shortened, the gingival attachments may be reduced, and the enamel may be hypoplastic, contributing to poor dental health. There are other described associations such as umbilical, auditory, pituitary, psychomotor, size, urethral and anal anomalies as well as albinism. Pathophysiology
The molecular genetics of Axenfeld–Rieger syndrome are poorly understood, but center on three genes identified by cloning of chromosomal breakpoints from patients.This disorder is inheritable as an autosomal dominant trait, which means the defective gene is located on an autosome, and only one copy of the gene is sufficient to cause the disorder when inherited from a parent who has the disorder. As shown in the diagram, this gives a 50/50 chance of offspring inheriting the condition from an affected parent.
Some mutations in genes associated with renal dysplasia (in syndromes) have been determined. The mutations in question occur at EYA1 or SIX1 genes (branchio-oto-renal syndrome). The PAX2 gene is also thought to play a role in MCDK.The contralateral kidney often undergoes hypertrophy. This is believed to be a compensatory mechanism to the non-functional MCDK. About 90% of patients with an MCDK will have contralateral hypertrophy into adulthood. The impact of contralateral hypertrophy on long-term renal outcomes is unknown. Diagnosis
MCDK is usually diagnosed by ultrasound examination before birth. Mean age at the time of antenatal diagnosis is about 28 weeks A microscopic analysis of urine in individuals with probable multicystic dysplastic kidney should be done. One meta-analysis demonstrated that unilateral MCDK occurs more frequently in males and the greater percentage of MCKD occur on the left side of the body. Treatment
MCDK is not treatable. However, the patient is observed periodically for the first few years during which ultrasounds are generally taken to ensure the healthy kidney is functioning properly and that the unhealthy kidney is not causing adverse effects. In severe cases MCDK can lead to neonatal fatality (in bilateral cases), however in unilateral cases the prognosis might be better (it would be dependent on associated anomalies). Epidemiology
In regard to the epidemiology of multicystic dysplasia kidney, the incidence of MCDK is estimated to be 1 in every 4,000 live births, making it rare in terms of the general population. References
Further reading
Al-Khaldi, N.; Watson, A. R.; Zuccollo, J.; Twining, P.; Rose, D. H. (1994).