Noonan Syndrome-related Myeloproliferative Disorder Occurring in the Neonatal Period: Case Report and Literature Review.

Noonan syndrome-related myeloproliferative disorder (NS/MPD) and juvenile myelomonocytic leukemia (JMML) are rare MPDs that occur in young children. We herein report a case of NS/MPD with neonatal onset. The patient had a characteristic appearance and high monocyte count in the peripheral blood and bone marrow. Genetic testing showed the E139D mutation in PTPN11 ; however, the patient did not meet all the diagnostic criteria for JMML, and we thus diagnosed him with NS/MPD. Eight other cases of NS/MPD with neonatal onset are also summarized. The initial presentation varied, and the prognosis was considered poor compared with previous reports of NS/MPD.

Immunodeficiency in a patient with microcephalic osteodysplastic primordial dwarfism type I as compared to Roifman syndrome.

BACKGROUND: Microcephalic osteodysplastic primordial dwarfism type I (MOPD I, also known as Taybi-Linder syndrome) is a rare genetic disorder associated with severe intrauterine growth retardation, short stature, microcephaly, brain anomalies, stunted limbs, and early mortality. RNU4ATAC, the gene responsible for this disorder, does not encode a protein but instead the U4atac small nuclear RNA (snRNA), a crucial component of the minor spliceosome. Roifman syndrome is an allelic disorder of MOPD I that is characterized by immunodeficiency complications. CASE REPORT: The patient described herein is an 18-year-old woman exhibiting congenital dwarfism and microcephaly with structural brain anomaly. She suffered human herpesvirus 6 (HHV-6)-associated acute necrotizing encephalopathy at the age of one, thereafter resulting in severe psychomotor disabilities. Genetic analysis using gene microarray and whole-exome sequencing could not identify the cause of her congenital anomalies. However, Sanger sequencing revealed a compound heterozygous mutation within RNU4ATAC (NR_023343.1:n.[50G > A];[55G > A]). Immunological findings showed decreases in total lymphocytes, CD4+ T cells, and T cell regenerative activity. Furthermore, antibodies against varicella-zoster, rubella, measles, mumps, and influenza were very low or negative despite having received vaccinations for these viruses. HHV-6 IgG antibodies were also undetected. DISCUSSION: The patient here exhibited a marked MOPD I phenotype complicated by various immunodeficiencies. Previous studies have not demonstrated immunodeficiency comorbidities within MOPD I subjects, but this report suggests an evident immunodeficiency in MOPD I. Patients with MOPD I should be treated with one of the immunodeficiency syndromes.