Potential therapeutic agent for the treatment of lung injury. In conclusion, the results reported in this work provide some support for considering ATII-LCs as appropriate candidates for ex vivo ATII cell models, with the possibility of introducing genetic modifications to study surfactant biogenesis, in particular protein and lipid synthesis, maturation, and traffic, as well as the packing and storage of surfactant lipid-protein complexes into LBs. Probands manifest a very recognizable pattern of malformations however there is a wide range of variability in phenotypic expression. Typical features include cognitive impairment, prenatal overgrowth followed by postnatal growth deceleration, hypotonia, seizures, cutaneous hypo and/or hyperpigmentation, facial dysmorphia including a high forehead, broad nasal bridge, telecanthus, sparse fronto-temporal hair at birth, high arched or cleft palate, posterior helical ear pits, short neck, supernumerary nipples, limb and genitourinary anomalies, congenital heart defects and diaphragmatic hernias. Isochromosome 12p is seen mainly in skin fibroblast cultures and in chorionic villus and amniotic fluid cell samples but can be identified in blood lymphocytes during the neonatal and early childhood period. The isochromosome is often lost in the peripheral blood, presumably due to a selective growth advantage of the karyotypically normal disomic cell populations in the bone marrow of PKS individuals. The percentage of tetrasomic cells does not correlate with severity of the syndrome, the patient’s longevity, or degree of mental retardation. The prevalence of cells with an extra metacentric chromosome i is usually highly variable and tissue-limited or tissue-specific mosaicism is a well-described characteristic of PKS. Diagnosis of PKS, especially in those individuals beyond the neonatal period, traditionally requires a skin biopsy and GS-5734 analysis of fibroblasts. The constellation of structural and neurocognitive deficits seen in PKS in a highly conserved manner, coupled with a narrow minimal critical region delineated on 12p13.31 would suggest that a few genes within this region that are critical regulators of human development are responsible for the PKS phenotype when present in extra copies. In order to effect the pleiotropic manifestations observed in PKS the critical gene on 12p are likely to be key regulators of downstream genes or gene networks important for the growth and differentiation of the tissues affected in this diagnosis. In order to begin to delineate the downstream 12p effector genes in PKS we used the Affymetrix Human Genome U133 plus 2.0 arrays to perform a genome-wide expression analysis in 17 probands with PKS and 9 age, gender and race matched controls.