Pediatric-Congenital BM failure disorders Flashcards
What is the differential diagnosis for congenital bone marrow failure?
- FA (Fanconi Anemia)
- DBA (Diamond-Blackfan Anemia)
- DC (Dyskeratosis Congenita)
- SDS (Shwachman-Diamond Syndrome)
- SCN (Severe Congenital Neutropenia)
- CAMT (Congenital Amegakaryocytic Thrombocytopenia)
- TAR (Thrombocytopenia Absent Radii Syndrome)
NWhat is the differential diagnosis for Acquired Neoplastic bone marrow failure?
- Hypocellular MDS
- Hairy cell leukemia
- Aleukemic leukemia
- PNH, T-LGL
List 5 medication can cause BM failure marrow failure?
Drugs:
* Chemicals, ionizing radiation
* Toxins (e.g., benzene, glue vapors, arsenic)
* Anti-seizure agents (carbamazepine, phenytoin)
* Antibiotics (sulfonamides, chloramphenicol)
* NSAIDs (phenylbutazone, indomethacin)
* Anti-thyroid medications (methimazole, propylthiouracil)
* Gold
Miscellaneous:
PNH, thymoma, pregnancy, anorexia nervosa, B12 deficiency
List 4 infection can cause BM failure marrow failure?
Infection:
Epstein-Barr virus, HIV, other herpes viruses
Seronegative hepatitis
Immune disorders:
Eosinophilic fasciitis, systemic lupus erythematosus, GVHD
List 2 immune diseases can cause BM failure marrow failure?
- Eosinophilic fasciitis
- systemic lupus erythematosus,
- GVHD
Miscellaneous:
- PNH
- thymoma
- pregnancy
- anorexia nervosa
- B12 deficiency
What are the clinical features of Fanconi anemia?
- Bone marrow failure (80% by age 20)
- No physical findings (~20%)
- More likely to be diagnosed in adulthood
- Short stature
- Microcephaly
- Cafe au lait spots (intense patchy brown pigmentation)
- Kidney and thumb malformations
Increased:
MCV, ADA, HbF
Macrocytic anemia
What is the pathophysiology of Fanconi anemia?
- Hypersensitivity to genetic damage due to mutations affecting the Fanconi anemia core complex (FANC) or other proteins in the DNA repair pathway.
- Progressive DNA damage causing aplastic anemia is uncertain, but it is thought to involve the accumulation of DNA damage in hematopoietic progenitors (HP).
What are the genetics of Fanconi anemia?
- At least 15 different genes can be affected.
- 8 FA proteins make up the core complex (A, B, C, D, E, F, G, L, and M).
- > 80% of cases involve mutations in FANC-A, C, or G.
- FANCD1 is associated with a severe phenotype.
- The FA pathway coordinates DNA repair in response to genotoxic insults (e.g., detecting interstrand crosslinks).
What is the inheritance pattern of Fanconi anemia?
- Autosomal recessive (usually)
- or X-linked recessive (FANCB) (rare).
- FANCR is autosomal dominant (AD).
- Homozygosity or double heterozygosity is required to cause disease.
- Very heterogeneous phenotype
What is the lab diagnosis for Fanconi anemia?
- Chromosome breakage studies on phytohemagglutinin-stimulated peripheral blood lymphocytes, cultured with and without clastogenic agents.
- Report results by comparing chromosomal aberrations to control populations.
What are two clastogenic agents used in Fanconi anemia testing?
Mitomycin C
Diepoxybutane
Compare and contrast Fanconi anemia, Ataxia telangiectasia, and Nijmegen breakage syndrome:
Name 3 syndromes associated with chromosome fragility.
- Fanconi anemia
- Ataxia telangiectasia
- Nijmegen breakage syndrome
What is the association between Fanconi anemia and AML?
700-fold increased risk of AML.
30% of FA patients have a solid tumor by age 45.
Fanconi
What are the main problems with HSCT in Fanconi anemia?
Only treatment for BM failure and risk of MDS/AML, but doesn’t address non-hematopoietic malignancies.
Inherent chromosomal fragility limits chemotherapy and radiation options, increasing the risk of other cancers.
Difficult to find related stem cell donors without familial disease.
What are the diagnostic criteria for dyskeratosis congenita?
1) Two out of four classic features:
* Abnormal reticular skin pigmentation
* Nail dystrophy
* Leukoplakia
* Bone marrow failure (BM failure)
2) Two or more other somatic features associated with DC
What is the underlying pathophysiology of dyskeratosis congenita?
Telomeropathy
9 genetic abnormalities affecting telomere maintenance have been identified.
Defective telomere maintenance leads to cellular senescence (aging).
What is the inheritance pattern of dyskeratosis congenita?
- Can be X-linked (DKC1)
- Can be autosomal dominant or autosomal recessive
- Genetic heterogeneity
- Genetic anticipation is prominent (phenotype worsens and appears earlier in second-generation patients)
What is the male to female ratio of dyskeratosis congenita?
10:1 (more common in males)
What are the consequences of telomeropathy in dyskeratosis congenita?
- Genomic instability
- Stem cell loss
- Defective cellular repair and regeneration → Leads to liver fibrosis and pulmonary fibrosis.
How is dyskeratosis congenita diagnosed?
Flow FISH is used to identify telomere shortening in lymphocytes.
Sequencing is done to identify specific mutations.
What are the four main genes involved in dyskeratosis congenita and their inheritance patterns?
* X-linked gene:
DKC1 (best characterized form of DC)
Autosomal dominant genes:
TERC, TERT, TINF2
TERT and TERC can also be autosomal recessive
What is Hoyeraal-Hreidarsson syndrome?
A severe X-linked form of dyskeratosis congenita
Associated with cerebellar hypoplasia.
What is the most common clinical manifestation of dyskeratosis congenita that is NOT part of the classic triad?
Idiopathic pulmonary fibrosis
Patients can also develop hepatic fibrosis.
TRIAD: oral leukoplakia, nail dystrophy, and reticular hyperpigmentation
What is the main cause of mortality in dyskeratosis congenita?
60-70% die of bone marrow failure.
What are the two main treatment options for dyskeratosis congenita?
Hematopoietic stem cell transplantation (HSCT)
Oxymetholone (an anabolic steroid that improves hematopoietic function in 2/3 of patients)
What is Diamond-Blackfan anemia (DBA)?
A congenital bone marrow failure syndrome that causes red cell aplasia (congenital pure red cell aplasia).
No other cytopenias are present.
The underlying genetics are poorly understood.
What are the two treatment options for Diamond-Blackfan anemia?
Low dose steroids
Transfusion support
What are the 4 diagnostic criteria for DBA?
Age < 1 year
Macrocytic anemia with no other significant cytopenias
Reticulocytopenia
Normal marrow cellularity with a paucity of erythroid precursors
What are the supportive criteria for diagnosing DBA in patients who do not meet the main criteria?
Major criteria:
Presence of a gene mutation associated with DBA
Positive family history
Minor criteria:
Elevated ADA activity
Congenital anomalies associated with DBA
Elevated Hgb F
No evidence of another inherited bone marrow failure syndrome
What are the clinical features of Diamond-Blackfan anemia?
Progressive reticulocytopenia, usually macrocytic anemia in infancy or early childhood.
Normal cellularity of the BM with decreased or absent erythroid precursors.
Congenital malformations in 50% of patients (craniofacial, thumb or upper limb abnormalities, cardiac defects, urogenital malformations, cleft palate).
Increased risk of malignancies.
Increased risk of endocrine dysfunction.
hat are the bone marrow features of Diamond-Blackfan anemia?
Presents in the first year of life with macrocytic anemia.
Paucity of red cell precursors on bone marrow examination.
Normal cellularity with markedly decreased or absent erythroid precursors.
What are the genetics of DBA? Name 5 genes and specify which is most common and which is X-linked.
AD genes:
RPS19 (most common, 25%)
RPS7, RPS10, RPS17, RPS24, RPL35A, RPL11, RPS26
XLR gene:
GATA1
Mutations in genes encoding ribosomal subunit proteins, leading to increased p53, favoring apoptosis.
What is the underlying pathophysiology of Shwachman-Diamond syndrome?
90% of cases have a mutation in the SBDS gene at 7q11.
The SBDS gene plays an important role in the maturation of the 60S ribosomal subunit, making SDS a disorder of ribosome biogenesis.
What are the bone marrow features of Shwachman-Diamond syndrome?
Hypocellular bone marrow with granulocytic hypoplasia.
What are the clinical features of Shwachman-Diamond syndrome?
Pancytopenia (often), but primarily neutropenia, which may be cyclical.
Pancreatic exocrine insufficiency.
Growth retardation.
Skeletal abnormalities.
What is severe congenital neutropenia (SCN)?
A group of disorders that affect granulopoiesis.
* Typically presents in infancy with severe life-threatening bacterial infections.
1-How many types of severe congenital neutropenia are there?
2- What is the most common type of severe congenital neutropenia, and what gene is involved?
1-At least 7 genetic lesions have been identified, each causing different clinical phenotypes.
2- SCN1 is the most common form, accounting for 60-80% of cases.
It is an autosomal dominant disorder caused by mutations in the ELANE gene on chromosome 19p13.3, which encodes neutrophil elastase.
What is the typical inheritance pattern of severe congenital neutropenia?
It is variable, but the most common type (SCN1) is autosomal dominant.