EIF2AK4 Mutations in Patients Diagnosed With Pulmonary Arterial Hypertension

BACKGROUND

Differentiating pulmonary venoocclusive disease (PVOD) and pulmonary capillary hemangiomatosis (PCH) from idiopathic pulmonary arterial hypertension (IPAH) or heritable pulmonary arterial hypertension (HPAH) is important clinically. Mutations in eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) cause heritable PVOD and PCH, whereas mutations in other genes cause HPAH. The aim of this study was to describe the frequency of pathogenic EIF2AK4 mutations in patients diagnosed clinically with IPAH or HPAH.

METHODS

Sanger sequencing and deletion/duplication analysis were performed to detect mutations in the bone morphogenetic protein receptor type II (BMPR2) gene in 81 patients diagnosed at 30 North American medical centers with IPAH (n = 72) or HPAH (n = 9). BMPR2 mutation-negative patients (n = 67) were sequenced for mutations in four other genes (ACVRL1, ENG, CAV1, and KCNK3) known to cause HPAH. Patients negative for mutations in all known PAH genes (n = 66) were then sequenced for mutations in EIF2AK4. We assessed the pathogenicity of EIF2AK4 mutations and reviewed clinical characteristics of patients with pathogenic EIF2AK4 mutations.

RESULTS

Pathogenic BMPR2 mutations were identified in 8 of 72 (11.1%) patients with IPAH and 6 of 9 (66.7%) patients with HPAH. A novel homozygous EIF2AK4 mutation (c.257+4A>C) was identified in 1 of 9 (11.1%) patients diagnosed with HPAH. The novel EIF2AK4 mutation (c.257+4A>C) was homozygous in two sisters with severe pulmonary hypertension. None of the 72 patients with IPAH had biallelic EIF2AK4 mutations.

CONCLUSIONS

Pathogenic biallelic EIF2AK4 mutations are rarely identified in patients diagnosed with HPAH. Identification of pathogenic biallelic EIF2AK4 mutations can aid clinicians in differentiating HPAH from heritable PVOD or PCH.

Inconsistent Results With Different Secondary Reflex Assays for Resolving HER2 Status

OBJECTIVES

Guidelines suggest that secondary reflex testing may be useful for resolving HER2 status in breast cancers with equivocal results by both immunohistochemistry (IHC) and in situ hybridization (ISH). We compared two reflex ISH assays and a polymerase chain reaction (PCR) assay for this application.

METHODS

Twenty-nine breast cancers with equivocal IHC and ISH results were retested two ways: (1) ISH using differentially labeled probes targeting ERBB2 ( HER2 , 17q12) and either RAI1 (17p11.2) or ORC4 (2q22.3-2q23.1) in two separate assays and (2) real-time quantitative PCR amplification of ERBB2 and a control locus ( EIF5B , 2q11.2).

RESULTS

Results of the HER2 / RAI1 and HER2 / ORC4 ISH assays were concordant for 21 (72%) cases, and results of all three secondary reflex assays were concordant for only 18 (62%) cases. Result discrepancies between the two ISH readers were observed for cases close to the cutoff threshold.

CONCLUSIONS

Use of different control loci for ISH is associated with discordant results, and PCR is more likely to classify cases as nonamplified, possibly due to contamination with nontumor cells. While resolution of HER2 -equivocal results is desirable from a clinical perspective, different secondary reflex assays yield different results, and the correlation of these results with clinical outcomes is unknown.