Congenital isolated adrenocorticotropin deficiency: an underestimated cause of neonatal death, explained by TPIT gene mutations.

Tpit is a T box transcription factor important for terminal differentiation of pituitary proopiomelanocortin-expressing cells. We demonstrated that human and mouse mutations of the TPIT gene cause a neonatal-onset form of congenital isolated ACTH deficiency (IAD). In the absence of glucocorticoid replacement, IAD can lead to neonatal death by acute adrenal insufficiency. This clinical entity was not previously well characterized because of the small number of published cases. Since identification of the first TPIT mutations, we have enlarged our series of neonatal IAD patients to 27 patients from 21 unrelated families. We found TPIT mutations in 17 of 27 patients. We identified 10 different TPIT mutations, with one mutation found in five unrelated families. All patients appeared to be homozygous or compound heterozygous for TPIT mutations, and their unaffected parents are heterozygous carriers, confirming a recessive mode of transmission. We compared the clinical and biological phenotype of the 17 IAD patients carrying a TPIT mutation with the 10 IAD patients with normal TPIT-coding sequences. This series of neonatal IAD patients revealed a highly homogeneous clinical presentation, suggesting that this disease may be an underestimated cause of neonatal death. Identification of TPIT gene mutations as the principal molecular cause of neonatal IAD permits prenatal diagnosis for families at risk for the purpose of early glucocorticoid replacement therapy.

Comparison of different treatment regimens in a case of homozygous familial hypercholesterolemia.

The laboratory results of five periods of different treatment regimens were compared in a 19-year-old girl with homozygous familial hypercholesterolemia (FH): weekly low-density lipoprotein (LDL) apheresis sessions with dextran sulfate columns (LA 15, Kaneka Corporation, Osaka, Japan) without statin administration; weekly LDL apheresis with polyacrylate columns (DALI, Fresenius Adsorber Technology, Bad Homburg, Germany) without statin; LDL apheresis as in Period 2 with 40 mg atorvastatin daily; LDL apheresis as in Period 2 with 80 mg atorvastatin daily; and fortnightly LDL apheresis sessions with polyacrilate and administration of 80 mg atorvastatin daily. The five treatments were given in the above order, and each lasted at least 2 months. To compare the effectiveness of the different methods, the blood levels of total cholesterol, LDL-cholesterol and high-density lipoprotein (HDL)-cholesterol were measured before each session, and the percentage decreases in the blood levels of total cholesterol and LDL-cholesterol were recorded during sessions in Periods 1 and 2. In Periods 1 and 2, the biological effectiveness of LDL apheresis was comparable. Atorvastatin (40 mg daily) improved the blood levels of total cholesterol and LDL-cholesterol, but lowered HDL-cholesterol values. Increasing the daily dose of atorvastatin from 40 mg to 80 mg did not significantly improve LDL-cholesterol levels. When the time between two sessions was longer (Period 5), the total cholesterol and LDL-cholesterol values worsened and were comparable to those of Period 2 during which there was no atorvastatin treatment. In this case of homozygous FH, weekly sessions of LDL apheresis in association with atorvastatin at dose of 40 mg per day gave the best results.

Human and mouse TPIT gene mutations cause early onset pituitary ACTH deficiency.

Tpit is a highly cell-restricted transcription factor that is required for expression of the pro-opiomelanocortin (POMC) gene and for terminal differentiation of the pituitary corticotroph lineage. Its exclusive expression in pituitary POMC-expressing cells has suggested that its mutation may cause isolated deficiency of pituitary adrenocorticotropin (ACTH). We now show that Tpit-deficient mice constitute a model of isolated ACTH deficiency (IAD) that is very similar to human IAD patients carrying TPIT gene mutations. Through genetic analysis of a panel of IAD patients, we show that TPIT gene mutations are associated at high frequency with early onset IAD, but not with juvenile forms of this deficiency. We identified seven different TPIT mutations, including nonsense, missense, point deletion, and a genomic deletion. This work defines congenital early onset IAD as a relatively homogeneous clinical entity caused by recessive transmission of loss-of-function mutations in the TPIT gene.