Family A belongs
to Village Manga, District Mardan, Khyber Pakhtunkhwa province. The family members
are engaged in regular farming and cattle herding. Inter marriages are a common
practice here which results in genetic disorders. The pedegree drawing
presented in Figure
indicate four generations with 2 affected males (IV-1 and IV-2) and 2 affected
female (IV-5 and IV6) individuals. Consanguineous marriage has been shown in the pedigree in
3rd generation and the disease appeared in 4th generation.
The pedigree analysis shows that affected individuals were produced by
unaffected parents and the affected status was independent of the sex
suggesting that the trait is transmitted in autosomal recessive manner. Pedigree analysis strongly suggests
the autosomal recessive mode of inheritance.

Autosomal recessive primary microcephaly is congenital in
all the affected individuals. Affected individuals are mild to moderate
mentally retarded but they have no other associated abnormality. Blood samples
were collected from five members including three affected (IV-1, IV-2, IV-6)
and two normal individuals (III-2 and IV-7) and DNA was isolated using standard
phenol-chloroform method.

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Family
B

Family
B is living in Mardan city of Khyber Pakhtunkhwa province. The pedigree was
constructed after careful investigations with the family elders. This family has four generations
comprising of 11 members including two affected one male and one female (IV-2 and IV-3) figure.
Consanguineous marriage has been
shown in the pedigree in 3rd generation and the disease appeared in 4th
generation.
Affected individuals are produced by normal parents which are carriers of the
disease, after lapse of generations, thus suggesting that the trait is
transmitted in autosomal recessive mode.Clinical findings confirmed that the
disease was congenital autosomal recessive microcephaly and was not associated
to any environmental causes or part of syndrome.

Blood
samples were collected from five individuals of whom two were affected (IV-2 and IV-3) and three were nomal
(III-1, III-2 and IV-1). Phenol-chloroform method was
followed for DNA extraction.

Genetic Mapping of Candidates Genes
for Autosomal Recessive Primary Microcephaly

On
the basis of genetic linkage studies in autosomal recessive primary microcephaly,
it is clear that at least some candidate intervals should be tested for linkage
or exclusion prior to embarking on genome-wide scan. Seventeen candidate loci
(MCPH 1-17) for autosomal recessive primary microcephaly are known. In the present
study, both the families were tested for linkage to these known loci by
genotyping microsatellite markers mapped within the candidate linkage
intervals. Table 3.1
and 3.2 summarizes
the microsatellite markers in the region of known loci, which were used in the
present study for candidate gene mapping.  

 

 

 

 

 

 

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