Perlman syndrome (PS) (also called renal hamartomas, nephroblastomatosis and fetal gigantism) is a rare overgrowth disorder present at birth. It is characterized by polyhydramnios and fetal overgrowth, including macrocephaly, neonatal macrosomia, visceromegaly, dysmorphic facial features, and an increased risk for Wilms tumor at an early age. The prognosis for Perlman syndrome is poor and it is associated with a high neonatal mortality. Perlman syndrome is an uncommon genetic disorder grouped with overgrowth syndrome in which an abnormal increase is often noted at birth in the size of the body or a body part of the infant. The disorder, also called renal hamartomas, nephroblastomatosis and fetal gigantism, has also been grouped with Renal cell carcinoma. The characteristic features include polyhydramnios, fetal overgrowth, including macrocephaly, neonatal macrosomia, visceromegaly, dysmorphic facial features, and an increased risk for Wilms tumor at an early age. Signs and symptoms
Genetics
The gene thought to cause some of the cases of Perlman syndrome is DIS3L2 found on chromosome 2 at 2q37.2 and is thought to have an important role in the mitotic cell cycle. Although both sexes are affected, the sex ratio of male to female is 2:1. The syndrome has been described in both consanguineous and non-consanguineous couplings. No chromosomal abnormalities have been observed, except for in the case of Chernos et al., which showed a de novo mutation — an extra G positive band, a genetic mutation that neither parent possessed nor transmitted — on the tip of the short arm of chromosome 11.
SPECT studies
In a study by Joo et al., the researchers performed interictal studies, meaning they scanned the patients brain between attacks to find an underlying abnormality, rather than ictal scans, which look at the abnormalities that present themselves during an attack. The researchers found interictally decreased cerebral blood flow in the posterior parts of the bilateral caudate nucleus. However, the literature does state that although this could be a cause of PKD, it could also be a result of PKD. Another SPECT study showed an increase in the cerebral blood flow in the left posterior thalamus in a PKD patient during an attack. The researchers also subtracted the ictal from the postictal scans, and saw increased blood flow in the thalamus. They ultimately suggested that hyperactive blood flow in this area could be causing the pathophysiology of PKD. This study, however, was only performed on one patient, and would need to be replicated many more times in order to be generalized to the population of PKD patients. Other SPECT studies have been cited showing hyperactivity in the basal ganglia. fMRI studies
In a study by Zhou et al., the researchers performed fMRI studies on PKD patients, and analyzed the differences between the amplitude low frequency fluctuations (ALFF) of the patients. They found that the left postcentral gyrus and the bilateral putamen had increased ALFF in PKD patients. The researchers concluded that the hyperactivity in these regions suggested that there is a dysfunction in the basal ganglia-thalamo-cortical circuit in PKD.