04 - Genetic disorders Flashcards

1
Q

One dominant allele is enough to produce phenotype (heterozygous); diseases with mutations in key structural proteins/receptors are usually inherited in this manner; examples: Huntington disease, NF, Myotonic dystrophy, TSC, ADPKD, Familial polyposis coli, HS, vWD, Marfan syndrome, EDS (some types), OI, Achondroplasia, Familial hypercholesterolemia, AIP

A

Autosomal dominant

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2
Q

Two recessive alleles produce phenotype; enzyme deficiencies are usually inherited in this manner: examples: CF, PKU, Galactosemia, Homocystinuria, Lysosomal storage diseases, a-1-antitrypsin deficiency, Wilson disease, Hemochromatosis, Glycogen storage diseases, SCA, Thalassemias, CAH, EDS (some types), Alkaptonuria, Neurogenic muscular atrophies, Freidrich ataxia, Spinal muscular atrophy

A

Autosomal recessive

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3
Q

Most common lysosomal storage disorder; most common form is chronic, non-neuronopathic form (Type I); acute neuronopathic form (Type II) most severe; microscopically, distended phagocytic cells in spleen, liver, BM, LNs, tonsils, thymus and Peyer patches, with fibrillary cytoplasm crumpled tissue paper appearance).

A

Gaucher disease

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4
Q

In this pattern of inheritance, females in general are more affected than males (in any scenario), because one allele in a female is enough to manifest the trait; examples: Alport syndrome and Vitamin D-resistant rickets

A

X-linked dominant disorders

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5
Q

Most common of the chromosomal disorders; leading cause of MR; most common cause: nondisjunction of Ch21 during meiosis; diagnostic clinical features: flat facial profile, oblique palpebral fissures, and epicanthal folds.

A

Trisomy 21 (Down syndrome)

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6
Q

Prominent occiput, mental retardation, micrognathia, low-set ears, short neck, overlapping fingers, CHDs, renal malformations, limited hip abduction, and rocker-bottom feet are features of this syndrome.

A

Trisomy 18 (Edward syndrome)

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7
Q

In this pattern of inheritance, males are usually affected due to hemizygosity of the allele, but females may express phenotype due to random activation of one X chromosome; examples: DMD, Hemophilia A and B, CGD, G6PD deficiency, Agammaglobulinemia, Wiskott-Aldrich syndrome, DI, Lesch-Nyhan syndrome, Fragile X syndrome

A

X-linked recessive disorders

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8
Q

Microcephaly and mental retardation, microphathalmia, polydactyly, cardiac defects, umbilical hernias, renal defects, and rocker-bottom feet are features of this syndrome.

A

Trisomy 13 (Patau syndrome)

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9
Q

Components of Chromosome 22q11.2 deletion syndrome.

A

DiGeorge syndrome (CATCH22) and velocardiofacial syndrome

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10
Q

Patients with Ch22q11.2 deletion syndrome are at high risk of these disorders.

A

Schizophrenia and bipolar disorders

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11
Q

Condition characterized by 2X chromosomes and 1Y chromosomes; most common karyotype is 47XXY (90%); important cause of reduced spermatogenesis and male infertility; clinical features include: eunuchoid body habitus, testicular atrophy, micropenis, absence of secondary sex characteristics, etc.

A

Klinefelter syndrome

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12
Q

Complete or partial monosomy of X chromosome; female hypogonadism in phenotypic females; Most common abnormality is lack of entire X chromosome (45XO) (57%); single most important cause of primary amenorrhea; clinical features include: ovarian streaks, absence of secondary sex characteristics, short stature, cystic hygromas of head neck, preductal CoA, etc.

A

Turner syndrome

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13
Q

Type of hermaphrodism with presence of both ovarian and testicular tissue.

A

True hermaphrodism

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14
Q

Type of hermaphrodism characterized by disagreement between phenotypic and gonadal sex; examples: MRKH syndrome and androgenital syndromes

A

Pseudohermaphrodism

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15
Q

Property of trinucleotide repeat disorders wherein the disease worsens with each successive generation.

A

Anticipation

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16
Q

Most common cause of MR following Trisomy 21; involves CGG expansion in FMR1 gene in X-chromosome; most distinctive feature is macro-orchidism.

A

Fragile X-syndrome

17
Q

Autosomal dominant neurodegenerative disorder; CAG expansion on HTT gene on Ch4p16.3; relentlessly progressive and uniformly fatal.

A

Huntington disease

18
Q

Diseases featuring maternal inheritance; usually, fundamental defect is abnormality in the electron transport chain; examples: MELAS, Leber hereditary optic neuropathy (LHON)

A

Mitochondrial disorders

19
Q

Deletion in paternally derived Chromosome 15q11.2q13; clinical features include: mental retardation, hypotonia, profound hyperphagia, obesity, small hands and feet, and hypogonadism.

A

Prader-Willi syndrome

20
Q

Deletion in maternally derived Chromosome 15q12; clinical features include: mental retardation, ataxic gait, seizure, and inappropriate laughter happy puppet.

A

Angelman syndrome