7238 A rare cause of primary ovarian failure in an adolescent due to a genetic mutation in mitochondrial poly-A-polymerase (mTPAP) mRNA

Abstract

Abstract Disclosure: J. Epstein: None. S. Veera: None. J. Pappas: None. B.C. Shah: None. Primary ovarian insufficiency (POI) is a dysfunction or loss of ovarian follicles with associated amenorrhea. While most causes are idiopathic, approximately 15% of POI cases are due to single gene or chromosomal abnormalities, such as X chromosome abnormalities. Many of these nuclear genes encode for proteins that function within the mitochondria. Mitochondrial disorders affect tissues with high energy demand, such as the neurological, skeletal, cardiac, and endocrine systems. Furthermore, mature ovaries have a relatively higher concentration of mitochondria, which play a role in cellular respiration along with steroidogenesis. Mutations that disrupt these pathways can therefore lead to ovarian dysfunction. We present a case of a 17-year-old female with concern for primary amenorrhea. She underwent pubarche at age 12 years and thelarche at 14 years, with slowed progression. Height Z score was -1.61 and weight Z score was -0.41. Lab work at presentation was significant for LH 18.6 IU/L (N 2.4-12.6 IU/L), FSH 43.9 IU/L (N 1.1-9.6 IU/L), low estradiol <2.5 pg/mL (N 30-100 pg/mL), low total testosterone 8.3 ng/dL (N 15-31 ng/dL), unremarkable HbA1C, cortisol, thyroid levels, and a 46 XX karyotype. Pelvic ultrasound showed small ovarian volumes with a 1.9 cc right ovary, 1.5 cc left ovary consistent with lack of hormonal stimulation, and uterus length of 4.9 cm (N > 4 cm) consistent with early hormonal stimulation. She was started on transdermal estrogen replacement. Past medical history included stable pericardial effusion, episodes of supraventricular tachycardia, pre-cataracts, speech delays, mild learning disabilities, spastic diplegia, progressive gait abnormalities, ligamentous laxity, and recurrent patellar dislocations requiring multiple orthopedic limb surgeries. Family history was significant for parental consanguinity as first cousins. As the etiology of the POI remained unknown, genetic testing was completed. Whole exome sequencing (WES) revealed a homozygous pathogenic variant in the MTPAP gene: p.(Leu495Arg) (CTG>CGG): c.1484 T>G in exon 9 on chromosome 10p11.23. MTPAP, also known as SPAX4, TENT6, or PAPD1, is a nuclear-encoded polymerase involved in synthesizing the 3’ poly(A) tail of mitochondrial transcripts as well as in mRNA degradation. She was diagnosed with autosomal recessive MTPAP-related neurodevelopmental and movement disorder. Monogenic disorders affecting mitochondrial function are rare causes of POI. A high index of suspicion should be raised when a constellation of neurological, musculoskeletal, and cardiac problems co-exist. WES can be a very useful tool for uncovering rare genetic disorders. Further studies are needed to clarify details of organ specific mitochondrial dysfunction and possible therapeutics in individuals affected with MTPAP-related neurodevelopmental and movement disorders. Presentation: 6/1/2024